experiment 3.1 science form 2 answer

Sains Tingkatan 1, 2 & 3

Nota Sains Tingkatan 1, 2 & 3

Eksperimen 3.1 – Sains Tingkatan 2 (KSSM) Bab 3

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Science Form 2

KURIKULUM STANDARD SEKOLAH MENENGAH SCIENCE FORM 2 Writers Jariah binti Khalib Maznah binti Omar Badariah binti Hamzah Shamsulikram bin Abdul Hamid Translators Ram Kumari K. Raman Yew Chian-Hauo Sharon Chelvi Moorthy Shirley Monica Editors Nadiatulaini binti Azenan Kumutha Murugiah Designer Mohd Fauzi bin Mohamad Hassim Illustrator Wan Hamizan bin Wan Hussin 2017 KEMENTERIAN PENDIDIKAN MALAYSIA SERIAL BOOK NO. : 0076 ACKNOWLEDGEMENT KPM2017 ISBN 978-967-14472-7-7 The publisher would like to thank the following organisations and individuals for their invaluable First Published 2017 assistance and cooperation in the preparation of this © Ministry of Education Malaysia book: All rights reserved. No part of this publication may be Committee members of Quality Control, produced, stored in any retrieval system or transmitted Textbook Division, in any form or by any means, electronic, mechanical, Ministry of Education Malaysia photocopying, recording or otherwise, without prior permission of the Director General of Education, Ministry Curriculum Development Division, of Education Malaysia. Negotiation is subject to the Ministry of Education Malaysia calculation of royalty or honorarium. Officers of the English Language Teaching Published for Ministry of Education Malaysia by: Centre (ELTC), Karangkraf Network Sdn. Bhd. Teacher Education Division, Lot 2, Jalan Sepana 15/3, Ministry of Education Malaysia Off Persiaran Selangor, Seksyen 15, Dato’ Dr. Sheikh Muszaphar Shukor Al Masrie 40200 Shah Alam, Sheikh Mustapha Selangor Darul Ehsan. Telephone: 603-5101 3836 Datuk M. Magendran Fax: 603-5101 3685 Email: [email protected] Website: www.karangkraf.com Design and typesetting by: Datuk N. Mohanadas Karangkraf Network Sdn. Bhd. Font type: Minion Pro Datuk Dr. Mazlan Othman Font size: 11 pt. Universiti Perguruan Sultan Idris Nur Adlyka Ainul Annuar Printed by: Ultimate Print Sdn. Bhd. Lot 2, Jalan Sepana 15/3, Off Persiaran Selangor, Seksyen 15, 40200 Shah Alam, Selangor Darul Ehsan. ii C ontents Introduction v Theme 1: Maintenance and Continuity of Life 2 4 Chapter 1 Biodiversity 7 1.1 Diversity of Organisms 17 1.2 Classification of Organisms Summative Practice 1 Chapter 2 Ecosystem 20 22 2.1 Energy Flow in an Ecosystem 25 2.2 Nutrient Cycle in an Ecosystem 2.3 Interdependence and Interaction Among Organisms and between 28 39 Organisms and the Environment 42 2.4 Role of Humans in Maintaining a Balanced Nature Summative Practice 2 Chapter 3 Nutrition 44 46 3.1 Classes of Food 53 3.2 Importance of a Balanced Diet 60 3.3 Human Digestive System 3.4 Process of Absorption and Transportation of Digested 66 71 Food and Defecation Summative Practice 3 Chapter 4 Human Health 74 76 4.1 Infectious and Non-infectious Diseases 82 4.2 Body Defence 90 Summative Practice 4 Theme 2: Exploration of Elements in Nature 94 96 Chapter 5 Water and Solution 106 5.1 Physical Characteristics of Water 113 5.2 Solution and Rate of Solubility 121 5.3 Water Purification and Water Supply Summative Practice 5 124 126 Chapter 6 Acids and Alkalis 133 6.1 Properties of Acids and Alkalis 137 6.2 Neutralisation Summative Practice 6 iii Theme 3: Energy and Sustainability of Life 140 142 Chapter 7 Electricity and Magnetism 152 7.1 Electricity 158 7.2 Flow of Electric Current in a Series Circuit and 164 166 Parallel Circuit 168 7.3 Magnetism 175 Summative Practice 7 201 Chapter 8 Force and Motion 250 252 8.1 Force 266 8.2 Effects of Force 268 270 Summative Practice 8 277 Chapter 9 Heat 204 279 284 9.1 Relationship between Temperature and Heat 206 287 9.2 Heat Flow and Thermal Equilibrium 207 288 9.3 Principle of Expansion and Contraction of Matter 213 9.4 Relationship between Types of Surface of Object, and 216 Heat Absorption and Emission 220 Summative Practice 9 Chapter 10 Sound Waves 222 224 10.1 Characteristics of Sound Waves 229 10.2 Loudness and Pitch of Sound 232 10.3 Phenomena and Application of Reflection of Sound Waves 235 Summative Practice 10 Theme 4: Earth and Space Exploration 238 240 Chapter 11 Stars and Galaxies in the Universe 249 11.1 Stars and Galaxies in the Universe Summative Practice 11 Chapter 12 Solar System 12.1 Solar System Summative Practice 12 Chapter 13 Meteoroid, Asteroid, Comet 13.1 Other Objects in the Solar System; such as Meteoroids, Asteroids and Comets Summative Practice 13 Answers Glossary Bibliography Index iv I ntroduction The Science Form 2 textbook is written for Form 2 students based on the Standard-Based Curriculum and Assessment for Form 2 prepared by the Ministry of Education. This book is written with more emphasis on thinking skills, information and communication skills, decision- making and problem-solving skills so that students can master the skills needed in the 21st century. Additionally, STEM Teaching and Learning approach is incorporated through approaches such as inquiry, problem-solving and projects to elevate students’ interest towards science and technology. To achieve this objective, this book incorporates special features as follow: 8.2.2 Today Histor y in Learning Standards based on the Information Magical SCIENCE regarding history Standard-Based Curriculum Appreciating the and Assessment for of science wonders of science teacher’s reference My World Application of science in the daily life of students My Malaysia! Science Latest information Additional regarding information related achievement to the topics of science in Brain Teaser Malaysia Questions that Formative Practice challenge thinking Provides questions to test students’ understanding at the end of each subtopic v Various activities in this book: Experiment Inquiry Project Discussion Types of Technology activities Simulation Visit New features in this book: 21st 21st Century Skills Thinking & Problem-solving skills Century Interpersonal skills & Self-directed learning Information & communication skills ST EM STEM (Science, Technology, Engineering and Mathematics) As a teaching and learning approach which applies and integrates knowledge, skills and values of STEM through inquiry, problem-solving or projects in the context of daily life. This approach hopes to attract students’ interest to pursue STEM education in school and enter the STEM workforce to tackle challenges and be competitive globally. ST EM Career in STEM field (Science, Technology, Engineering and Mathematics) vi Components at the end of a chapter: 2 1 SELF-REFLECTION Simple checklist of Summary learning standards for students’ reference Summary of a chapter Summative Practice HOTS Mastery Questions to test students’ Levels 5 and 6 understanding at the end HOTS questions of a chapter 4 3 HOTS Questions (Applying, analysing, evaluating, creating) Digital components in this book: Download the free QR reader application from the App Store or Play Store Video Video Interactive Quiz quiz Additional Info information vii Guideline to scan AR for Three-dimensional Animations and Interactive Games Step 1 Download the free QR reader application from the App Store or Play Store. Step 2 Download the free AR Buku Teks application by scanning the QR code below. or Step 3 Accompanied by audio SCAN Interactive Find the pages that have these icons. IMAGE SCAN IMAGE games Three- dimensional animations Step 4 Scan the image on the page with your smartphone or tablet and enjoy the three-dimensional animations and interactive games. Three-dimensional animations Interactive games viii 1 Maintenance and Continuity of Life What is the importance of biodiversity to humans? How can we maintain the balance of nature? Why is it important to have a healthy lifestyle? What are the practices that strengthen our immune system? 1 Chapter 1 Biodiversity What is biodiversity? Why is it important to classify organisms systematically? How is biodiversity conserved? Let’s understand: Diversity of organisms Classification of organisms 2 Chapter 1 : Biodiversity Science Blog SCIENCE BLOG The Rafflesia in Malaysia Malaysia is the habitat of the world’s largest flower, the rafflesia (Rafflesia sp.). The rafflesia is a parasitic plant that feeds on its host. The rafflesia gives off a rotting smell when in full bloom. This flower is also very unique because it does not have any leaves to carry out photosynthesis, nor does it have roots to absorb water and nutrients from the soil. Keywords Reptile Fish Biodiversity Amphibian Vertebrate Monocotyledon Invertebrate Dicotyledon Mammal Bird 3 1.1 Diversity of Organisms Did you know that our country, Malaysia, is one of the 12 megabiodiversity countries in the world? The equatorial climate of Malaysia makes it a very ideal habitat for a variety of organisms. Can you name the animals and plants shown in Photograph 1.1? Diversity of animals and plants in Malaysia Photograph 1.1 Diversity of animals and plants in Malaysia Science What is Biodiversity? Biodiversity also covers diversity at the genetic The diversity of organisms, whether microorganisms, animals or level. Genetic diversity is the plants, is known as biodiversity. Biodiversity exists as a result of diversity within a species, the diversity of habitat and climate. Different organisms have based on variations in the different characteristics which enable them to adapt and thrive genes of each microorganism, independently in their respective habitats (Photograph 1.2). animal or plant. Desert Polar regions Soil Sea 4 Photograph 1.2 Diverse organisms in different habitats 1.1.1 Chapter 1 : Biodiversity The Importance of Biodiversity Today Histor y in Biodiversity is a priceless treasure and a legacy of nature which should be preserved. Can you list down some of the importance of biodiversity The International Day based on Photograph 1.3? for Biological Diversity is celebrated on the 22nd of May every year. Sources of food Balance in nature Recreational places Animals and plants supply Cycle of nutrients, Areas that are rich in food to humans. pollination and interaction biodiversity can be between organisms create developed as recreational Medical balance in nature. places. Raw materials for industries Education Herbs are widely used in the Timber, bamboo and rattan Humans increase knowledge manufacture of medicines and are examples of forest products and create new technology cosmetics. which are used to make through scientific research on musical instruments, furniture microorganisms, animals and and to build buildings. plants. Photograph 1.3 Importance of biodiversity 5 Effective Biodiversity Management Photograph 1.4 Deforestation activities It cannot be denied that we need raw materials such as timber cause animals to lose their habitat and for development. Nevertheless, deforestation activities need to be controlled to preserve our biodiversity from extinction food sources Science (Photograph 1.4). An endemic species is a species that What methods can we use to maintain and conserve lives in clusters within a restricted biodiversity? Biodiversity can be maintained and conserved by: habitat in a specific location. Examples of endemic plants and animals in • banning the killing or trade of endemic and Malaysia include the rafflesia, pitcher endangered animals and plants through the plant (Nepenthes rajah), leatherback Wildlife Protection Act 1972, turtle, Malayan tiger and the Borneo Pygmy elephant. • protecting the habitat through creating national parks, marine parks, forest reserves and wildlife sanctuaries, • undertaking reproductive programmes such as seedling nurseries to help with reforestation and turtle hatcheries. A ctivity 1.1 Science Aim: To conduct a discussion on effective biodiversity The methods of biodiversity management. conservation can be classified as in situ conservation and ex situ Instruction conservation. In situ conservation, 1. Work in groups. preserves the species within 2. Find information on: their natural habitat such as in national parks, permanent forest (a) factors that cause the extinction of animals and plants reserves and marine parks. Ex situ (b) ways to preserve and conserve animals and plants conservation, on the other hand, preserves the species outside of including endemic and endangered species their natural habitat such as in zoos 3. Present your group findings in class. and botanical parks. Biodiversity http://www.nre.gov.my Formative Practice 1.1 Info 1. What is biodiversity? 2. How does biodiversity contribute to the economy? 3. What is an endemic species? Give two ways to preserve and conserve endemic species. 4. Give examples of endangered species in Malaysia. 6 1.1.2 Chapter 1 : Biodiversity 1.2 Classification of Organisms The two main groups of organisms are animals and plants. Animals and plants can be classified further into smaller groups based on their common and different characteristics. Study Photograph 1.5. What are the similarities and differences between the two animals? Classification of Animals Photograph 1.5 Animals can be classified as invertebrates and vertebrates. Can you state the differences between these two groups of animals? Invertebrates Invertebrates are animals without a backbone. Figure 1.1 shows the classification of invertebrates. Invertebrates Without legs With legs Without segmented With segmented Three pairs of More than three pairs body body legs of legs Figure 1.1 Classification of invertebrates Science Invertebrates Without Legs Segmented body is the division of an animal's body into several segments. 1 Without segmented body • There are invertebrates without legs and without segmented bodies. Sponge Sea anemone Corals Planaria Snail Photograph 1.6 Invertebrates without legs and without segmented bodies 7 2 With segmented body • Some invertebrates without legs have segmented bodies. Tapeworm Segment Earthworm Leech Photograph 1.7 Invertebrates without legs with segmented bodies Science Invertebrates With Legs Insects are the largest group Characteristics of invertebrates with legs: of animals. There are 950 000 species of insects. • have segmented bodies • have hard outer shells (exoskeleton) 1 Three pairs of legs Ant Butterfly Cockroach Photograph 1.8 Invertebrates with three pairs of legs 8 2 More than three pairs of legs Chapter 1 : Biodiversity Spider Horseshoe crab Prawn Centipede Scorpion Photograph 1.9 Invertebrates with more than three pairs of legs Vertebrates Vertebrates are animals with a backbone (Figure 1.2). Vertebrates Fish Amphibians Reptiles Birds Mammals Figure 1.2 Classification of vertebrates Science Fish A poikilotherm is an Fish are animals with the following common characteristics: organism that has a body temperature that changes • poikilothermic according to its surrounding • covered in hard and slimy scales temperature. A homeotherm, • have fins and a tail on the other hand, is • breathe through gills an animal with a body • lay eggs temperature that is constant • undergo external fertilisation and free from the influence of its surrounding temperature. Clown fish Grouper Eel Photograph 1.10 Examples of fish 1.2.2 9 Amphibians Salamander Amphibians are animals with the following common characteristics: Toad • poikilothermic • live on land and in water • covered with moist skin • young amphibians breathe through gills • adult amphibians breathe using their lungs and moist skin • produce jelly-like eggs (spawn) without a shell • undergo external fertilisation Frog Frog spawn Tadpole Photograph 1.11 Examples of amphibians Reptiles Reptiles are animals with the following common characteristics: • poikilothermic • produce eggs with a shell • breathe through lungs • have scales and hard skin • undergo internal fertilisation Iguana Turtle Snake Crocodile Photograph 1.12 Examples of reptiles 10 Birds Chapter 1 : Biodiversity Birds are animals with the following common characteristics: Science • homeothermic • covered with feathers to maintain body temperature The rhinoceros • breathe through lungs hornbill is a protected • have wings that help some birds to fly animal in Malaysia. It • have a pair of scaly feet is the state bird of • undergo internal fertilisation Sarawak. • produce eggs with hard shell SCAN Owl IMAGE Kingfisher Let's play Duck My Malaysia! Photograph 1.13 Examples of birds Mammals Malaysia is a habitat for nearly Mammals are animals with the following 742 species of birds. At least common characteristics: 522 species are local species, • homeothermic 192 are migratory species • covered with fur or hair and 52 are local species with • breathe through lungs migratory characteristics. • undergo internal fertilisation • give birth and nurse their young Brain Teaser What is the difference between fur and hair? Bat Giraffe Elephant Photograph 1.14 Examples of mammals Lion 11 Classification of Plants Plants are classified as non-flowering and flowering plants. Plants Non-flowering plants Flowering plants Figure 1.3 Classification of plants Science Non-flowering Plants Non-vascular plants are simple and small plants Non-flowering plants consist of moss, fern and conifer. What are without a vascular system. the common characteristics of each of these groups of plants? Vascular plants have a Non-Flowering Plants vascular system within them that transport water and food throughout the plant. These plants also have true roots, stems and leaves. Moss Fern Conifer • Reproduce by • Reproduce by • Reproduce by bearing producing spores producing spores cones • Non-vascular • Vascular • Vascular Figure 1.4 Classification of non-flowering plants 12 Chapter 1 : Biodiversity Flowering Plants Flowering plants produce flowers which become fruits that contain seeds. Each seed has a cotyledon, which is stored food that is used by the seed to germinate. A seed which has one cotyledon is called a monocotyledon. A seed with a pair of cotyledons is called a dicotyledon (Figure 1.5). Paddy plant Orchid plant Lotus plant Sunflower plant Photograph 1.15 Examples of flowering plants Dicotyledons Differences Monocotyledons One Number of cotyledons Two Fibrous root Root Tap root Leaves with parallel veins Leaf Leaves with network-like veins Most have non-woody stem Stem Woody stem Paddy and maize plants Example Tomato plant and durian tree Parallel veins Network-like Tap root veins 13 Fibrous root Figure 1.5 Differences between monocotyledons and dicotyledons A ctivity 1.2 Aim: To identify the characteristics which differentiate major taxonomy groups. Instruction 1. Work in groups. 2. Identify the differences between (a) plants, animals and fungi (b) fish, amphibians, reptiles, birds and mammals 3. Present the results using a multimedia presentation. Constructing a Dichotomous Key A dichotomous key is a method used by biologists to identify and classify organisms systematically based on similarities and differences. It is constructed of a series of couplets. Each couplet consist of two statements describing characteristics of a particular organism or group of organisms. Let’s look at the example of a dichotomous key for animals (Figure 1.6) and plants (Figure 1.7). Pomfret Chicken Lion Frog Snake Dichotomous key 1. (a) Poikilothermic ...............................................................................go to 2 (b) Homeothermic ............................................................................. go to 3 2. (a) Scaly skin .................................................................................... go to 4 (b) Non-scaly skin ............................................................................. Frog 3. (a) Non-feathered ............................................................................. Lion (b) Feathered ................................................................................... Chicken 4. (a) Does not have fins ...................................................................... Snake (b) Has fins ....................................................................................... Pomfret Figure 1.6 Example of a dichotomous key for animals 14 Chapter 1 : Biodiversity Maize plant Marchantia sp. Fern Gnetum sp. Sunflower plant Dichotomous key 1. (a) Non-flowering ............................................................................ go to 2 (b) Flowering .................................................................................. go to 3 2. (a) Non-vascular ............................................................................. Marchantia sp. (b) Vascular .................................................................................... go to 4 3. (a) Monocotyledon .......................................................................... Maize plant (b) Dicotyledon ................................................................................ Sunflower plant 4. (a) Does not produce seeds ............................................................ Fern (b) Produce seeds ........................................................................... Gnetum sp. Figure 1.7 Example of a dichotomous key for plants A ctivity 1.3 Aim: To construct a dichotomous key. Instruction 1. Work in groups. 2. List down as many invertebrates found in your school compound. 3. Construct a dichotomous key for the invertebrates. 4. Present your group findings in class. Formative Practice 1.2 1. Classify the following animals according to their common characteristics. 2. The sunflower plant and paddy plant are flowering plants. State one similarity and three differences between the two plants. 3. Give two differences between monocotyledon and dicotyledon plants. 15 16 Summary Biodiversity Meaning Management Classification using Dichotomous key Importance Effects of Ways of preserving Animals Plants Food source human activities and conserving Balance in nature on biodiversity biodiversity Recreational place Invertebrates Vertebrates Non-Flowering Flowering Medicine Monocotyledon Raw material Moss Fern Conifer Education Without legs With legs Quiz Dicotyledon Three pairs of Fish Reptiles Mammals Interactive Quiz 1 legs Amphibians Birds More than three pairs of legs Without With segmented segmented body body Chapter 1 : Biodiversity SELF-REFLECTION After learning this chapter, you are able to: 1.1 Diversity of Organisms Elaborate and communicate on biodiversity. Justify the needs of effective biodiversity management. 1.2 Classification of Organisms Differentiate organisms using a dichotomous key based on common characteristics. Characterise the major taxonomy groups. Summative Practice 1 1. Complete the crossword puzzle below with the correct answers. (e) (c) T L (a) I (d) T I (f) E (b) G A Across Down (a) The diversity of organisms whether (d) are animals which have animals, plants or microorganisms is backbones. known as . (e) Fish breathe through . (b) Amphibians are or (f ) An is an example of a cold-blooded. reptile. (c) A key is used by biologists to identify and classify organisms systematically. 17 2. Tick (3) the true statement and cross (✗) the false statement. (a) Biodiversity is the diversity of living and non-living organisms. (b) Biodiversity is very important for the continuity of human’s existence. (c) Apart from classifying living things, a dichotomous key can also be used to classify non-living things. 3. Liana and some of her friends collected the following five types of animals when they conducted a sampling activity in a forest. Three pairs of Three pairs of Three pairs of Four pairs of More than four pairs of legs legs legs legs legs P Q R S T (a) Complete the following dichotomous key based on the physical characteristics of the animals collected by them. Five animals: P, Q, R, S, T Three pairs of (iv) legs (i) With wings Body with two (v) Ant segments (P) (ii) Thin and fragile Spider Centipede wings (S) (T) Ladybird (iii) (R) (b) What are the similarities between animals P, Q, R, S and T ? (c) What are the differences between animals P, S and T ? 18 4. Observe Figure 1. Chapter 1 : Biodiversity (a) Suggest two characteristics that can be used to classify plants. (b) Give three similarities between plant A and plant B. Plant A Plant B Figure 1 5. Sik Mei observed similarities between the three animals in Photograph 1. Sik Mei thinks that the three animals are in the same group. Is Sik Mei correct? Give your reasons. Scorpion Jellyfish Crab Photograph 1 6. List the differences between the animals in Photograph 2. Construct a dichotomous key to identify the animals. Planaria Butterfly Earthworm Photograph 2 HOTS Mastery 1 7. Deforestation is a huge threat on a global level. Nevertheless, it contributes to the development of a nation. Justify the needs for deforestation. 8. Photograph 3 shows a leatherback turtle, an endemic animal. Hunting this animal has serious consequences. Justify. Photograph 3 19 Cha pter 2 Ecosystem How does energy flow in an ecosystem? What kind of interaction exists between living things? How is the knowledge on interaction between living things applied in agriculture? Let’s understand: Energy flow in an ecosystem Nutrient cycle in an ecosystem Interdependence and interaction among organisms, and between organisms and the environment Role of human in maintaining a balanced nature 20 Chapter 2 : Ecosystem Science Blog SCIENCE BLOG Programme to Control Monkey Population The Department of Wildlife and National Parks (PERHILITAN) carried out a programme to control the monkey population in Taman Tasik Perdana in the year 2010. This programme was an alternative method to solve the conflict between humans and monkeys. The method used in this programme was sterilisation. It was performed on male monkeys. Then, these sterilised monkeys were released into their original habitat. The monkey population growth rate was studied to observe the effectiveness of this programme. Keywords Population Community Ecosystem Mutualism Producer Commensalism Consumer Parasitism Decomposer Saprophytism Food chain Food web Species 21 2.1 Energy Flow in an Ecosystem D o you know that the source of energy in all ecosystems originates from the Sun? Green plants convert light energy from the Sun into chemical energy through the process of photosynthesis. The chemical energy is transferred to primary consumers and then to secondary and tertiary consumers in the food chain and food web. Producers, Consumers and Decomposers In an ecosystem, organisms can be classified as producers, consumers and decomposers. Producer Primary consumer A producer is an organism that produces A consumer is an organism that eats its own food through photosynthesis. another organism. Primary consumers Most plants are producers. are herbivores and omnivores that eat producers. For example, caterpillars. Caterpillar Plant Dead Brain Teaser Decomposer A decomposer is an organism that breaks What are the materials that down dead animals and plants into simpler cannot be broken down by a materials or nutrients. This interaction is decomposer? known as saprophytism. Figure 2.1 Examples of producer, consumer and decomposer in a forest ecosystem 22 2.1.1 Chapter 2 : Ecosystem Secondary consumer Brain Teaser A secondary consumer is an omnivore and carnivore that eats the primary consumer. For Are human beings primary, example, the Himalayan bluetail, Tarsiger rufilatus, secondary or tertiary is an omnivore because it eats caterpillars and fruits. consumers? Explain. However, the kingfisher, Alcedo atthis, is a primary carnivore because it eats primary consumers such as Construct Food Chains snails, fish, tadpoles and shrimps. http://www.vtaide.com/png/ foodchains.htm#create Himalayan Info bluetail SCAN IMAGE Let’s play Tertiary consumer A tertiary consumer is a secondary carnivore that eats a secondary consumer. The size of a tertiary consumer is usually bigger than a primary or secondary consumer. Fox Science Mushroom Some examples of decomposers are mushrooms that grow on decaying wood, mould that grows on food as well as E.coli bacteria that break down food molecules in the large intestine of humans. 23 Food Chain A food chain can be used to show the feeding relationship between organisms. Figure 2.2 shows an example of a food chain. Cabbage Snail Bird Fox (Producer) (Primary consumer) (Secondary consumer) (Tertiary consumer) Food Web Figure 2.2 Example of a food chain The interconnection of a few food chains is called a food web. Figure 2.3 shows an example of a simple food web in a vegetable garden. Can you write four food chains that create the food web shown? Caterpillar Bird Energy flow Snail Cabbage Snake Grasshopper Frog Figure 2.3 Example of a food web Energy Flow in a Food Web As seen in the food chain, energy is also transferred from one organism to another organism in the food web. In reality, some of the energy is lost because it is used by the organism to move and carry out the life process of respiration. Apart from this, energy is also lost in the form of heat energy or chemical energy through undigested food, or faeces. Cabbage Caterpillar Bird Snake Energy flow Snail Frog Energy loss Grasshopper Figure 2.4 Energy flow in a food web A ctivity 2.1 Aim: To construct a food web. Instruction 1. Visit any ecosystem in your school compound or your housing area. 2. Construct as many food chains as possible from the plants and animals you find. 3. Interconnect the food chains to make a food web. Then, identify the producers, consumers and decomposers in the food web. 4. Discuss the energy flow in the food web. 24 2.1.2 Chapter 2 : Ecosystem Formative Practice 2.1 1. The following is an example of a food chain. Identify the producer, primary consumer, secondary consumer and tertiary consumer. Cabbage Caterpillar Chicken Snake 2. Based on the following organisms: Paddy plant Grasshopper Sparrow Owl Rat Caterpillar (a) construct a food web. (b) predict what will happen if the paddy plant dies because of a long drought. 2.2 Nutrient Cycle in an Ecosystem The transfer of nutrients and energy is continuous in an ecosystem. Nutrients are obtained from a balanced ecosystem and used by living things. Then, the nutrients are returned to the environment to be used again. This cycle is called a nutrient cycle. Do you still remember the examples of nutrient cycles, such as the water cycle, carbon cycle and oxygen cycle that you learned in Form One? What is the role of living things in those cycles? Water Cycle Condensation The role of living things in the water forms cloud cycle • Water is absorbed by roots of plants Rain in the ground and released into the Respiration, Surface runoff atmosphere through transpiration. defecation and Animals carry out respiration, defecation and excretion (sweating excretion and urination). All of these increase the water content in the atmosphere. Transpiration • Roots of plants hold the soil tightly and make the structure of the soil Evaporation more compact. This slows down the flow of water underground and Water seeps prevents soil erosion. underground • Leaves that fall from trees and cover the surface of the earth will reduce Water is absorbed Groundwater storage the rate of evaporation and prevent by roots of plants the soil from becoming dry. Figure 2.5 Water cycle 25 2.2.1 2.2.2 Carbon Cycle and Oxygen Cycle 4 Oxygen in Release of Plants carry out the atmosphere carbon dioxide photosynthesis and Use oxygen release oxygen 1 Respiration by Release Carbon dioxide animals oxygen in the atmosphere consumes 2 Respiration by oxygen plants consumes oxygen Plant respiration Animal respiration Plants are eaten releases carbon releases carbon by animals. dioxide dioxide Carbon is stored Plants die in the body Decomposition tissues Decomposition releases carbon Animals die 3 dioxide Decay by Decomposition decomposers consumes Decomposers oxygen (Bacteria and fungi) Figure 2.6 Carbon and oxygen cycles are inter-connected The role of living things in the carbon cycle and oxygen cycle 1 2 Plants and animals carry out respiration which uses oxygen and releases carbon dioxide. 3 The decay of dead plants and animals by bacteria and fungi in the soil uses oxygen and releases carbon dioxide. 4 Green plants maintain the content of carbon dioxide and oxygen in the air through photosynthesis which absorbs carbon dioxide and releases oxygen. A ctivity 2.2 21st Century Aim: To create a multimedia presentation that connects the role of living things in the water cycle, oxygen cycle and carbon cycle. Instruction 1. Work in groups. 2. Design a water cycle, a carbon cycle and an oxygen cycle using multimedia. 3. Predict the effects to the nutrient cycle if the water cycle, oxygen cycle or carbon cycle are affected. 4. Present the multimedia presentation in class. 26 Chapter 2 : Ecosystem Steps to Solve Problems when there is an Interference to the Nutrient Cycle You have learned the role of plants in maintaining the balance of oxygen and carbon dioxide in the atmosphere. Nevertheless, human activities such as unrestricted logging, burning of fossil fuels and overconsumption of water resources for agricultural and domestic purposes have negatively affected the nutrient cycle. Can you think of steps to solve these problems? Unrestricted logging Burning of fossil fuels Overconsumption of water resources Create planned Use public transport Store rain water for daily agricultural systems use Replant trees Tighten laws Photograph 2.1 Human activities that disrupt the nutrient cycle and steps to solve the problem Formative Practice 2.2 1. Name three types of nutrient cycles. 2. Give two processes that change the state of matter in the water cycle. 3. Explain the role of organisms in the carbon cycle and oxygen cycle. 4. Suggest two steps to save water. 27 2.2.3 2.3 Interdependence and Interaction among Organisms, and between Organisms and the Environment Before we study the interdependence and interaction among organisms, and between organisms and the environment, let us understand a few important terms first. 1 Habitat A habitat is the natural surroundings or home of an organism. 2 Species 3 Population 4 Community A species is a group of A population is a group A community is a few organisms that have of organisms of the populations of different common characteristics same species that live organisms that live together in and can reproduce to in the same habitat. one habitat and have mutual breed offsprings. interaction with one another. Dragonfly Species A population of dragon flies 5 Ecosystem An ecosystem is a few communities that live together in one habitat and have mutual interaction with one another, including all the Pond community non-living components such as water, air and soil. Dragonfly Grass Water hyacinth Mosquito larvae Fish Water snail Tadpole Figure 2.7 Pond ecosystem 28 2.3.1 Chapter 2 : Ecosystem A Balanced Ecosystem Organisms in an ecosystem are interdependent on each other to ensure the survival of the species. These organisms are also interdependent on non-living components in the environment such as water, light, air and soil. The interdependence that exists between organisms and their natural surroundings creates a balanced ecosystem. An ecosystem is said to be balanced if the living organisms and non-living components in the environment are in a state of harmony without any external interference. Imagine the state of a forest ecosystem if the trees were cut down. Would this ecosystem still be balanced? A ctivity 2.3 ST EM Aim: To study the habitats, populations and communities in an ecosystem. Instruction 1. Work in groups. 2. Find a natural ecosystem in your area. 3. Conduct an observation of that ecosystem. 4. Take photos and list the species, populations and communities ST EM of animals and plants that can be found in that ecosystem. A person who is an expert 5. Prepare a folio of the information that you have obtained. in the study of ecosytems is Questions called an ecologist. 1. How do different populations obtain food? 2. How do living organisms interact with their surroundings? 3. What are the benefits that exist from the interaction of organisms and their surroundings? 4. Name an organism and predict what will happen if the population of that organism dies. Brain Teaser Most natural ecosystems are Can you name a few other balanced if there is no external man-made ecosystems? interference. Are man-made ecosystems such as aquariums also balanced? Photograph 2.2 Example of a man-made ecosystem (aquarium) 29 You have already learned that living organisms are interdependent on one another and also on non-living components to create a balanced ecosystem. What is the effect of these non-living components on the distribution of animals and plants? Let us carry out Experiment 2.1. Experiment 2.1 Aim: To study the influence of temperature, light and humidity on the distribution of organisms. A The effect of temperature on the distribution of organisms Problem statement: What is the effect of temperature on the distribution of woodlice? Hypothesis: Woodlice are more likely to gather in a place with medium temperature. Variables: (a) Constant variables: The number of woodlice, light and humidity (b) Manipulated variable: Temperature (c) Responding variable: Distribution of woodlice Materials: Woodlice, hot water and room temperature water (26°C – 30°C) Apparatus: Petri dish with partition, Petri dish lid, wire gauze, pliers and stopwatch Procedure: 1. Pour 20 ml of hot water (50°C) into partition P of a Petri dish and 20 ml of room temperature water Hot water Water (26°C – 30°C) into partition Q of the same Petri dish. (50°C) (26°C – 30°C) 2. Use a pair of pliers to make a wire gauze mould. 3. Place the wire gauze mould on the Petri dish. Wire gauze mould Petri dish Woodlice 4. Put 10 woodlice on the wire gauze above the Petri lid dish and cover with the lid (Figure 2.8). 5. Leave the apparatus in an open area in the laboratory for five minutes. 6. Record the number of woodlice found in each partition. Partition P Partition Q Figure 2.8 Conclusion: Is the hypothesis accepted? Give your reasons. B The effect of light on the distribution of organisms Problem statement: What is the effect of light on the distribution of woodlice? Hypothesis: Woodlice are more likely to gather in a dark place. Variables: (a) Constant variables: The number of woodlice, room temperature and humidity (b) Manipulated variable: Light (c) Responding variable: Distribution of woodlice 30 Chapter 2 : Ecosystem Material: Woodlice Apparatus: Petri dish with partition, wire gauze mould, Petri Wire gauze mould dish lid, black cloth and stopwatch Black cloth Woodlice Procedure: Petri 1. Pour 20 ml of room temperature water into partition R dish and S of a Petri dish with partition. lid 2. Use the wire gauze mould made in Experiment A. Partition R Partition S 3. Place the wire gauze mould on the Petri dish. Water (26°C – 30°C) 4. Put 10 woodlice on the wire gauze mould. Figure 2.9 5. Cover the Petri dish lid of partition R with a black cloth (Figure 2.9). 6. Leave the apparatus in an open area in the laboratory for five minutes. 7. Record the number of woodlice found in each partition. Conclusion: Is the hypothesis accepted? Give your reasons. C The effect of humidity on the distribution of organisms Problem statement: What is the effect of humidity on the distribution of woodlice? Hypothesis: Woodlice are more likely to gather in a damp place. Variables: (a) Constant variables: The number of woodlice, room temperature and light (b) Manipulated variable: Humidity (c) Responding variable: Distribution of woodlice Material: Woodlice Apparatus: Petri dish with partition, wire gauze mould, Wire gauze mould Petri dish lid, anhydrous calcium chloride and stopwatch Water Woodlice Procedure (26°C – 30°C) Petri dish 1. Pour 20 ml of room temperature water (26°C – 30°C) lid into partition T of a Petri dish. Anhydrous 2. Place anhydrous calcium chloride into partition U of Partition T Partition U calcium the same Petri dish. chloride 3. Place the wire gauze mould on the Petri dish. Figure 2.10 4. Put 10 woodlice on the wire gauze mould. 5. Cover the Petri dish with the lid (Figure 2.10). 6. Leave the apparatus in an open area in the laboratory for five minutes. 7. Record the number of woodlice found in each partition. Conclusion: Is the hypothesis accepted? Give your reasons. 31 Importance of Adaptation of Living Things to the Environment Tropical areas receive high distribution of rainfall and sunlight throughout the year. Desert areas experience extreme hot and dry weather. Tundra areas experience long winters and short summers. How does wildlife adapt to the climate of their habitat in tropical, desert and tundra areas? Tropical Desert Tundra Photograph 2.3 Tropical, desert and tundra areas A ctivity 2.4 21st Century Aim: To carry out multimedia presentation on how animals and plants adapt to the climate of their habitats; in desert, tundra and tropics. Instruction 1. Work in groups. 2. Each group represents one of the three different areas of habitats; desert, tundra and tropics. 3. Collect materials from a variety of media about the habitat. 4. Discuss the adaptation of animals and plants to the climate in their habitats. 5. Present your results using a multimedia presentation. 32 2.3.2 Chapter 2 : Ecosystem Interaction between Organisms Interaction between organisms comprises symbiosis, prey-predator and competition. Types of interaction between organisms Symbiosis Prey-predator Competition Mutualism Commensalism Parasitism Video of Interaction between Organisms and Their Video Surroundings http://www.bukutekskssm.my/ Science/Video1.mp4 Figure 2.11 Types of interaction between organisms Symbiosis Symbiosis happens when two or more organisms of different species live closely together and interact with one another. Symbiosis includes mutualism, commensalism and parasitism. Mutualism • An interaction that benefits both organisms. Photograph 2.4 shows a few examples of mutualism. Fungi • The sea anemone protects the clown fish Algae from predators and supplies food to it. Lichens are algae and fungi that live together. • The clown fish cleans the sea anemone and • The fungi supply water and minerals to provides nutrients to the sea anemone in the form of waste. the algae. • The algae carry out photosynthesis and supply food to the fungi. Mynah • The mynah gets food from the buffalo by eating the lice that Buffalo stick to the body of the buffalo. 2.3.3 • The body of the buffalo is free of lice. Photograph 2.4 Examples of mutualism 33 Commensalism • The interaction between two organisms which only benefits one organism without harming or benefitting the other. • Commensal is the organism that benefits. The remora fish Shark (commensal) latches on the shark (host) and gets its food from scraps scattered by its host. Remora fish Bird’s nest fern The bird’s nest fern (commensal) grow in between the branches of trees (host) to get sunlight. Photograph 2.5 Examples of commensalism Parasitism • An interaction that benefits one organism only and harms the other. • Parasite is the organism that benefits. • Host is the organism that is harmed. The tapeworm (parasite) that lives in the human intestine (host) absorbs nutrients. Tapeworm Lice (parasite) suck the blood of humans and animals (host). Lice Photograph 2.6 Examples of parasitism 34 Chapter 2 : Ecosystem Prey-predator • Involves one organism that eats another organism. • Prey is the organism that is eaten by the predator. • Predator is the organism that hunts another organism for food. Predator Predator Prey Prey Photograph 2.7 Examples of prey-predator Competition • Competition happens when organisms in one habitat compete for limited supply of basic needs such as light, space, water, food and mates. Competition to get food Competition to get mate to reproduce Photograph 2.8 Examples of competition 35 Biological Control Biological control is a method that uses organisms that are natural predators, parasites or pathogens to reduce the number of pests in an area. Photograph 2.9 shows examples of biological control that are used in the agricultural sector in Malaysia. Owls are kept in palm oil plantations to control the population of rats. Rhinoceros beetle Bacillus thuringiensis is used to control pests, namely the rhinoceros beetle in palm oil plantations. The guppy is a predator to mosquito larvae in a pond. Guppy Mosquito larvae The ladybird beetle Ducks are reared in eats aphids, a crop paddy fields to eat pests such as snails pest. and insects. Photograph 2.9 Examples of biological control in Malaysia Biological control is more environmental friendly because it does not use pesticides or chemicals. Apart from this, this method is usually cheaper and does not affect humans’ health. Nevertheless, this method has a few weaknesses such as: • it takes a long time before any effect is seen. • the balance of the ecosystem might be disrupted because a new species is introduced into that ecosystem. 36 Chapter 2 : Ecosystem Factors that Influence Population Size in an Ecosystem How does population size change in an ecosystem? Among the factors that cause population size to change is disease, the presence of predators, source of food and change of weather. Disease The population of animals and plants decreases when a disease strikes. For example, avian flu in poultry-rearing areas and tobacco mosaic virus in tobacco crops. Photograph 2.10 Poultry affected Photograph 2.11 by a disease Tobacco crops struck Presence of predators by a disease The population size of a living organism is influenced Photograph 2.12 by the population size of its predator. For example, Zebra being eaten the size of the zebra population in the savanna by a lion ecosystem decreases with the presence of its predators such as the lion. Source of food Photograph 2.13 If a food source decreases, animals can be Panda threatened by extinction. For example, panda depends on bamboo as its primary food source. Clearing of forests has caused the destruction of its food source and habitat. In Malaysia, the crow population has increased due to the abundance of food scraps. Photograph 2.14 Crow Change of weather Droughts cause soil to become dry and infertile and increase the risk of forest fires. As a result, the population of plants and animals decreases. Photograph 2.15 Soil becomes dry and infertile Photograph 2.16 Forest fires resulting from a long drought 2.3.4 37 Changes in the Ecosystem Changes in the ecosystem such as limited water supply, animal migration and decrease or increase in population size can upset the balance between populations. Limited water supply • Paddy is a plant that requires a lot of water. • If there is a long drought season, this change in the ecosystem will upset the balance between populations in the paddy field. • The food web will be affected because the population of the producer, which is paddy, decreases. Photograph 2.17 Insufficient water supply disrupts the ecosystem of a paddy field Migration • The ecosystem can also change because of animal migration, moving from one place to another due to a change of season. • For example, the cattle egret (Bubulcus ibis) migrates to Kuala Gula, Perak from September to April every year. As a result, the number of insects such as grasshoppers, crickets, spiders, flies and worms decreases as they are eaten by the egrets. Photograph 2.18 Cattle egret which migrates to Kuala Gula, Perak Change in population size • The size of a population can decrease or increase because of changes in another population. • For example, the increase of pests such as beetles and caterpillars causes the population of plants to decrease. Science Photograph 2.19 Overpopulation of In 2015, the southern region of beetles destroys crops Russia was attacked by locusts which destroyed crops. Cornfields as wide as 800 hectares were destroyed in just a few hours. 38 2.3.5 Chapter 2 : Ecosystem Formative Practice 2.3 1. Fill in the boxes using the choice of answers given. (a) A group of goats in a grass field. (b) A small pond that has lotus plants, grass, a group of tadpoles, a few fish, ducks and frogs. (c) A grass field that becomes the living place of a group of goats. (d) A tropical rainforest where there are a variety of plants and animals that are interdependent on one another. 2. Based on the situation below, state the kind of interaction that happens between these living organisms. Situation Type of interaction (a) Two roosters fight to get a mate to reproduce (b) A cucumber plant wraps around the branch of a papaya tree (c) A rafflesia flower grows on the branch of a live tree 2.4 Role of Humans in Maintaining a Balanced Nature Nature is threatened by destruction because of human activities. As such, humans are responsible for conserving and maintaining the balance of nature. Table 2.1 Effects of human activities on the environment Activity Effects Forest logging Industrialisation • Extinction of flora and fauna species • Soil erosion Agriculture • Greenhouse effect Waste disposal • Pollution of air, water and soil • Acid rain • Greenhouse effect • Pollution of water due to overuse of pesticides and fertilisers • Soil loses minerals due to non-sustainable agriculture • Pollution of water and ground • Foul odour due to decaying organic • Flash floods waste matter Steps to solve the effects of human activities on the environment • Enforce laws The Forestry Department is always conducting law enforcement activities in all states. For example, carrying out patrols in the forest area, using helicopters and having road blocks to monitor the movement of timber-carrying lorries. 2.4.1 39 • Increase public awareness In schools, students are instilled with good values through Moral Education to appreciate the balance of nature. These good values are also instilled through mass media such as newspapers, radio and television. • Practise Refuse, Reduce, Reuse, Recycle, Repurpose (5R) The practice of refuse (not to use non-recyclable materials), reduce (reduce the number of materials to use), reuse (reuse the materials), recycle (recycle materials) and repurpose (use the materials for other uses) can reduce the waste materials. • Use biological control Avoid the use of pesticides that pollute the air and soil by carrying out biological control in agriculture. A ctivity 2.5 ST EM 21st Century Aim: To carry out a role play to discuss the importance of humans to manage and ensure the sustainability of life. Instruction ST EM 1. Work in groups. An environmental consultant 2. Each group has to choose one of the following cares for the environment environmental issues in Malaysia: from a science and (a) waste management system technology aspect to make it (b) flood dam project sustainable. (c) forest management (d) haze 3. Identify several agencies or stakeholders and public to solve the selected environmental issue. 4. Organise a forum to discuss: (a) the cause of the environmental issue (b) the effect of the evironmental issue on the local community (c) solutions for the issue 5. Each group member must represent the roles of agencies, stakeholders and the public in the forum. Formative Practice 2.4 1. List four human activities that can destroy the ecosystem. 2. State two effects for each of the following activities to the balance of nature. (a) Deforestation (c) Agriculture (b) Industrialisation (d) Waste disposal 3. Mr. Lim wants to start a sustainable oil palm plantation. In your opinion, how can Mr. Lim control the rat population that frequently destroys crops? 4. Haze happens more frequently in our country. State: (a) the cause of haze (b) the effects of haze on people and the environment (c) the steps to be taken to avoid haze from happening 5. Give two reasons why humans need a balanced ecosystem. 40 Summary Factors that change of size Species Producer influence Population Primary consumer • Disease Community Secondary consumer • Predator Ecosystem (Primary carnivore) • Food source Tertiary consumer • Weather (Secondary carnivore) Organisms interdependent Environment Balanced has interact with one ecosystem another Nutrient cycle requires Types of interaction Humans’ role Water cycle Oxygen cycle Symbiosis Prey-predator Competition Carbon cycle used in Chapter 2 : Ecosystem 41 Mutualism Commensalism Parasitism Biological used in control Interactive Quiz 2 Quiz SELF-REFLECTION After learning this chapter, you are able to: 2.1 Energy Flow in an Ecosystem Explain through examples; producer, consumer and decomposer. Interpreting food chains and food webs. 2.2 Nutrient Cycle in an Ecosystem Elaborate and communicate the role of living things in oxygen and carbon cycles in an ecosystem. Justify the role of organisms in water cycle in an ecosystem. Solve problems when there is an interference to the cycles due to human activities. 2.3 Interdependence and Interaction among Organisms, and between Organisms and the Environment Explain through examples interdependence among living things and the environment in maintaining a balanced ecosystem. Justify the importance of adaptation of living things to the environment. Communicate through examples the interaction between organisms and apply these interactions in daily life. Separate the factors that affect the size of population in an ecosystem. Predict how the changes in ecosystem affect resources and balance of population. 2.4 Role of Humans in Maintaining a Balanced Nature Justify and communicate why humans need a stable and productive ecosystem for the sustainability of life. Summative Practice 2 1. Based on the food web in Figure 1, answer the following questions. Fox Rabbit Rat Grass Sapling Figure 1 42

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Chapter 8 : Force and Motion 2. Attach two Magdeburg hemispheres together and Seal turn the screws to remove the air inside. Try to pull and Vacuum separate the two hemispheres (Figure 8.40). Can you do it? Explain this phenomenon. Pull Pull Seal Figure 8.40 3. Fill a beaker with water and put in a drinking straw. Close the upper end of the straw (Figure 8.41). Lift up the straw. Observe what happens to the water in the straw. Explain Drinking your answer. straw Water Beaker Drinking Figure 8.41 straw 4. Arrange the apparatus as shown in Figure 8.42. Fill a Water Rubber tube rubber tube with water. Close both ends of the rubber tube. Then, place one end of the rubber tube in the water Level of and the other end at a lower point outside the basin. water Observe what happens to the water in the basin. What surface happens if both ends of the tube are at the same level? Basin End of Figure 8.42 the tube 5. Insert a syringe into a glass of water (Figure 8.43). Pull the Syringe piston upwards. Observe what happens. Water 6. Scatter shredded papers on the floor. Then, use a vacuum Glass cleaner to suck all the shredded papers (Figure 8.44). Observe what happens. How does the vacuum cleaner Figure 8.43 function? Explain all the observations above using labelled figures to show Figure 8.44 the action of atmospheric pressure. Note: Students need to use the terms air pressure and atmospheric pressure correctly. 193 Application of the Concept of Air Pressure in Daily Life Plunger ᕡ Reduced Pull Air 1 When the plunger is pressed Push air Plunger pressure pressure further against the sink, the air Plunger Air reduced inside it will be forced out forced External air and creates an area of low Water out Water ᕢ pressure pressure. Blockage Sink 2 The high pressure in the pipe pushes out the blockage stuck Blockage inside the sink when the plunger is pulled up. Magdeburg Hemisphere Atmospheric 1 When the air in the hemisphere is pumped out pressure ᕢ so that the space in the hemisphere becomes a vacuum, the pressure in the hemisphere is zero. ᕡ 2 The two hemispheres cannot be separated because Vacuum the atmospheric pressure outside will exert a very strong force on the hemispheres. Atmospheric Airtight seal pressure Straw ᕢ ᕡ 1 When air in the straw is sucked, the pressure inside Atmospheric Pressure less than the straw is reduced. pressure atmospheric pressure 2 The higher air pressure outside (atmospheric pressure) will push the drink into the straw and finally into the mouth. Liquid being pushed up the straw Syphon Atmospheric pressure Tube filled 1 The end of tube B is placed lower than the end ᕣ with water ᕢ of tube A, causing water to flow out from it. A 2 Water in the tube flows out and creates an area B ᕡ of low pressure in the tube. 3 Atmospheric pressure pushes the water into the tube, so the water flows out continuously. 194 Chapter 8 : Force and Motion Application of the Concept of Air Pressure in Daily Life Syringe Low pressure ᕡ 1 When the piston is pulled up, the volume of air in the Piston ᕢ cylinder increases. This causes a low air pressure in Atmospheric Liquid the cylinder. pressure 2 The higher air pressure outside (atmospheric pressure) will push the liquid into the syringe. Vacuum cleaner Low pressure 1 When the switch is turned on, the fan in the vacuum Fan cleaner will push air out of the vacuum cleaner. This ᕡ causes the air pressure in the vacuum cleaner to drop. ᕢ 2 The higher atmospheric pressure outside will Air push the air and dust into the vacuum cleaner. High atmospheric pressure Dust Figure 8.45 Examples of application of air pressure in daily life My World Make another hole on the top Low air Higher atmospheric of the can so that air can flow pressure pressure outside in through the second hole to in the can the can balance the air pressure inside Mom, how Milk should I pour out and outside. Can the condensed A can of condensed milk with one hole – milk does not flow out easily due to high milk easily? pressure outside the can. Air pressure Small hole inside is the same as the air Milk flows pressure out due to outside gravitational pull A can of condensed milk with two holes – milk flows out easily because air pressure inside and outside the can is equal. 195 Relationship between Altitude and Atmospheric Pressure Do you know that atmospheric pressure depends on altitude? Atmospheric pressure decreases as altitude increases. This is due to gravitational attraction. Air molecules closer to the surface of the Earth are pulled together by the gravitational attraction causing a rise in pressure. At higher altitudes, air molecules are less affected by the gravitational attraction, so air becomes less heavy and expands easily. This causes a low atmospheric pressure at high altitude (Figure 8.46). My Malaysia! Lesser air molecules Low exert pressure on the pressure person who is at the peak of the mountain. More air molecules With the 'Malaysia Boleh' spirit, two exert pressure on the Malaysians, Datuk M. Magendran and person who is at the Datuk N. Mohanadas became the first foot of the mountain. two Malaysians to conquer Mount Everest on 23rd May 1997. The peak Figure 8.46 Atmospheric pressure at different altitudes of Mount Everest has an area of very low atmospheric pressure. High pressure Scan the QR codes below for more information regarding the relationship between altitude and atmospheric pressure. Altitude Calculator, Atmospheric Pressure and Analysis http://www.mide.com/pages/air-pressure-at-altitude-calculator Info Data Analysis Regarding Relationship between Altitude and Atmospheric Pressure http://www.windows2universe.org/earth/Atmosphere/pressure_vs_altitude.html Info Interactive Lab – Interactive Activity and Quiz http://sunshine.chpc.utah.edu/Labs/OurAtmosphere/atm_measure2.html Info 196 Chapter 8 : Force and Motion Effects of Depth on Liquid Pressure When a diver is diving in the sea, his body will experience pressure (Photograph 8.16). The weight of the sea water acting on the body of the diver causes the pressure. What will the diver experience if he dives deeper into the sea? Let us carry out Activity 8.11 to find out the answer. Photograph 8.16 Diver at Sipadan Island A ctivity 8.11 Aim: To study the effect of depth on pressure in liquids. Material: Water Apparatus: 50 cm rubber tube, basin and 1 000 ml measuring cylinder Instruction Measuring 1. Fill a measuring cylinder to the maximum volume cylinder and turn it upside down as shown in Figure 8.47. Air bubble 2. Put one end of a rubber tube into the measuring Air Basin cylinder. blown 3. Blow air into the other end of the rubber tube. Observe the change in size of the air bubbles rising from the bottom to the water surface. Figure 8.47 Questions 1. Compare the size of the air bubbles at the bottom of the basin and at the water surface. 2. State the relationship between volume of air bubbles and its depth in the water. 3. Explain this phenomenon in relation to pressure in liquids. Based on the results of Activity 8.11, the size of the air bubbles becomes larger as the air bubbles rise to the surface. This is caused by the decreasing liquid pressure as depth of liquid decreases. Scan the QR code below for additional information regarding the effects of depth on liquid pressure. Effects of Depth on Liquid Pressure http://oceanservice.noaa.gov/facts/pressure.html Info 8.2.8 197 Effects of Depth on Liquid Pressure in Daily Life Thin wall Low pressure High pressure Thick wall The walls of a dam are designed to be thicker at the base in order to withstand the high water pressure at the base of the dam. Awidthivsetarnwdeharigsha wspaetceirapl rseusistuinreo. rder to hmTihgaehtebwrioaadtleysroopftrhaeasstsuuibtrmwe.ialrlinnoetisbemcardueshoefdstbryong Photograph 8.17 Examples of effects of depth on liquid pressure 198 Chapter 8 : Force and Motion Magical SCIENCE ST EM It’s fun to try! Try carrying out the experiment shown in the video below to observe the effects of depth on liquid pressure. ST EM Mechanical engineers carry out research on dam designs, industrial plants, machines and many other things. They need knowledge of physics, Video of Pressure such as the concept of water in Liquids http:// pressure when building dams. bukutekskssm.my/ Science/Video2.mp4 Video Water from the bottom hole shoots out further than water from the upper hole due to pressure in liquid. Formative Practice 8.2 1. Figure 1 shows a lever system in equilibrium. Calculate the weight of X. X 10 N 1m 2m Fulcrum 5 cm 30 cm C Figure 1 10 cm A 2. Figure 2 shows a cuboid with a weight of 5 N. B (a) Which surface will exert the greatest pressure? (b) Calculate the pressure exerted by each surface. 3. A balloon filled with helium gas will rise upwards when released and float at a certain height. (a) Why does the balloon rise upwards? Figure 2 (b) Explain the change in the size of the balloon as it rises higher. (c) Show the forces acting on the balloon when it is floating with the help of a diagram. 199 200 Summary Force and Motion Force Effects of Force Types of forces Effects of force • Gravitational force • Moves stationary objects • Weight • Changes the velocity of objects • Normal force • Stops moving objects • Elastic force • Changes direction of motion of objects • Buoyant force • Changes shape and size of objects • Frictional force Difference in densities and effects of buoyancy on Characteristics of force daily life • Force has magnitude Lever system • Force has direction • Force has point of application • Effort Measuring force in S.I. unit using spring balance • Fulcrum • Weight of object • Load • Frictional force Moment of force For every force acting there is a reaction force of the Pressure and its application in daily life same magnitude but in the opposite direction Gas pressure and kinetic theory of gas • Object that remains on the table Atmospheric pressure and the effects of altitude • Object that floats on water on atmospheric pressure • Two trolleys in contact with each other are Effects of depth on liquid pressure released using spring mechanism Interactive Quiz 8 Quiz Chapter 8 : Force and Motion SELF-REFLECTION After learning this chapter, you are able to: 8.1 Force Describe and communicate about force. Explain that force has magnitude, direction and point of application. Measure force in S.I. unit. Explain with examples that every action force has an equal (same magnitude) reaction force but in the opposite direction. 8.2 Effects of Force Describe and communicate the effects of force. Explain and communicate the relationship between the differences in density and the effects of buoyancy in daily life. Classify and solve problems involving levers based on the position of fulcrum, load and effort. Explain and communicate about moment of force. Carry out experiment and communicate about pressure and its application in daily life. Elaborate and communicate about gas pressure based on the kinetic theory of gas. Explain and communicate the existence of atmospheric pressure and the effects of altitude on atmospheric pressure. Explain the effects of depth on liquid pressure. Summative Practice 8 1. Identify the following types of forces. (b) (a) Photograph 1 201 2. State the device used to measure force and the S.I. unit of force. Measuring device: S.I. unit: 3. Label the action force and the reaction force acting on the object in Photograph 2 below. Photograph 2 15 cm Force 4. Tick (3) the activity that involves atmospheric pressure. Inhaling air into lungs Opening a door Hanging a picture on the wall using a nail Drinking water from a straw 5. Figure 1 shows a nail being removed from a plank using a Figure 1 hammer. If a force of 5 N is required to remove the nail, what is the moment of force required to pull the hammer in the direction shown in Figure 1? 6. Figure 2 shows a car that has a weight of 1 000 N. The area of contact of each tyre with the road is 0.1 m2. Calculate (a) the total pressure exerted by the car on the road. (b) the pressure exerted by each tyre on the road. Figure 2 7. A piece of stone has a weight of 20 N in the air and 15 N when fully submerged in water. (a) Determine the difference in the weight of the stone in the air and in water. (b) Determine the upthrust force on the stone. (c) Explain why the stone sinks in water. 202 Chapter 8 : Force and Motion 8. Su Ling wants to use a straw to drink from a glass but she Hole could not suck the water. She finds a small hole on the straw (Figure 3). Suggest a method to overcome the problem. Straw Water Figure 3 9. Mei Foong is invited to an event held at a field. The field has a soft ground. She has two pairs of shoes as shown in Figure 4. Suggest the most suitable pair of shoes to be worn by Mei Foong to attend the event. Give your reasons. P Q Figure 4 10. Azman wants to transfer liquid from beaker B to beaker A (Figure 5). AB He has tried a few times but failed. What is the problem? Modify Figure 5 the set up so that the liquid can be transferred from beaker B to beaker A. Nurul HOTS Mastery 8 Wan 11. Wan and Nurul sat on a see-saw (Figure 6). The see-saw is imbalanced because Wan’s mass is 45 kg while Nurul’s mass is only 30 kg. Suggest how Nurul can balance the see-saw. Figure 6 12. Mr. Tan pushes a wheelbarrow on a muddy road (Figure 7). He finds it very difficult to push the wheelbarrow. Suggest one modification that can be made to reduce the pressure exerted on the road. Explain your answer. Figure 7 203 Cha pter Heat 9 Why are tall buildings fixed with shiny glass panels? Why does a thick glass break when it is filled with hot water? How do thermometers work? Why is a bonfire lit on a cold night? How does heat affect gas? Let’s understand: Relationship between temperature and heat Heat flow and thermal equilibrium Principle of expansion and contraction of matter Relationship between types of surface of object, and heat absorption and emission 204 Chapter 9 : Heat Science Blog SCIENCE BLOG Infrared Cameras Hardly Detect Polar Bears An infrared camera is an equipment used to detect heat emitted by the body and processes it to be shown as a thermal image. This equipment is often used to detect the location of animals or its habitat which is difficult to be seen with the naked eyes. However, researchers find it difficult to detect polar bears using this equipment. Polar bears, which live in cold climates trap heat beneath its layers of fat and furs so well that it is almost undetectable by the infrared camera. Keywords Heat Heat insulator Temperature Expansion Conduction Contraction Convection Land breeze Radiation Sea breeze Heat conductor Mercury 205 9.1 Relationship between Temperature and Heat Try to recall the knowledge of heat and temperature that you have learned in primary school. Heat is obtained from various sources such as the Sun, electrical appliances and burning of fuel. Heat is a form of energy. Heat flows from a hotter region to a colder region. What does temperature mean? Temperature is a measure of the degree of hotness or coldness of an object. Temperature increases in a hot environment and decreases in a cold environment (Photograph 9.1). Temperature is measured by using a thermometer. When water When ice cubes is heated, its are placed around temperature bottles of juice, increases. the temperature in the bottles decreases. Photograph 9.1 Temperature changes according to its surroundings Although heat and temperature are interrelated, both are not the same. Table 9.1 shows the differences between heat and temperature. Table 9.1 The differences between heat and temperature Heat Temperature A form of energy The degree of hotness or coldness of an object Measured in joule (J) Measured in degrees Celsius (°C) or kelvin (K) The amount of heat depends on the type of material, Temperature depends on the degree of quantity of material and temperature movement of the particles in a matter. Formative Practice 9.1 1. State the S.I. unit of heat. 2. Is the sense of touch a reliable method to determine if a person has fever? Give an explanation for your answer. 3. Tick (3) the correct statement about heat and temperature. (a) When water is boiled in two beakers filled with 100 ml and 200 ml of water respectively, the temperature of the water is the same. (b) The smaller the mass of water, the longer the time taken for the water to boil. 206 9.1.1 Chapter 9 : Heat 9.2 Heat Flow and Thermal Equilibrium Heat Flow H eat flows from a hot object to a cold object. Ice cream left at room temperature absorbs heat and melts. What would happen to a hot kettle if it is left at room temperature? Heat flow happens in three different ways, which are through conduction, convection and radiation. Let us carry out Activity 9.1 to understand these three ways of heat flow. Photograph 9.2 Ice cream melts at room temperature A ctivity 9.1 Aim: To show heat is transferred by conduction, convection and radiation. Materials: Candle wax, water, matches, candle, incense stick, potassium permanganate crystal and thumbtacks Apparatus: Copper rod, beaker, wire gauze, bell jar, bulb, T-shaped cardboard, thermometer, tripod stand, retort stand with clamp and Bunsen burner A Conduction Thumbtack Wax 1. Stick three thumbtacks on a copper rod using candle wax K LM Copper and set up the apparatus as shown in Figure 9.1. rod 2. Heat the end of the copper rod and observe the sequence Bunsen Retort in which the thumbtacks fall off. burner stand with clamp B Convection Figure 9.1 (i) Convection in liquid Wire Beaker gauze SafPerteycaution Water Tripod Make sure the potassium permanganate crystal sinks stand Potassium completely to the bottom of the beaker before it is heated up. permanganate crystal 1. Fill a beaker with water and set up the apparatus as Bunsen burner shown in Figure 9.2. Figure 9.2 2. Heat the beaker slowly and observe the direction in which the Glowing potassium permanganate crystal moves inside the beaker. incense stick (ii) Convection in gas T-shaped cardboard 1. Light a candle and place it inside a beaker on one side and place the T-shaped cardboard in the middle of the beaker (Figure 9.3). Beaker 2. Bring a glowing incense stick close to the mouth of the beaker on Candle the opposite side of the candle. 3. Observe the movement of smoke in the beaker. Figure 9.3 9.2.1 207 C Radiation To switch 1. Set up the apparatus as shown in Figure 9.4. 2. Fix the vacuum pump to the bell jar and remove the air from Bell jar Hand the jar. 3. Place your palms on the sides of the bell jar to feel the heat. Bulb 4. Switch on the bulb. After 10 minutes, place your palms on the To vacuum pump Figure 9.4 sides of the bell jar to feel the heat. Questions 1. Give an inference for your observation in Activity A. 2. Draw the direction of the convection current in liquid. 3. What is the use of the incense stick in Activity B? 4. State other ways to detect surface heat of the bell jar in Activity C. Conduction Direction of heat flow • The process of heat transfer from hotter regions to Hot Cold colder regions through a solid medium. molecule molecule • The particles that receive heat energy will vibrate and collide with one another more frequently and transfer the heat to the whole medium. Hot fluid Brain Teaser Cold fluid Why does a carpet feel Convection warmer than marble tiles • Heat is transferred by the movement of fluid when we step on them? (liquid and gas) from hotter regions to Radiation colder regions. • The part of the fluid that receives heat will • The process of transferring heat expand, become less dense and rise. without any medium. • The colder and more dense fluid moves downwards. • Heat can propagate through an • The circulating stream that rises and falls empty space or vacuum. continuously is known as convection current. • The types of surface, temperature 208 and total surface area of an object will influence the rate of heat flow. Chapter 9 : Heat Heat Flow in Natural Phenomena Can you identify the method of heat flow from the Sun to the Earth? Heat energy from the Sun is transferred to the Earth through radiation. It is the only method that can propagate through an empty space (Figure 9.5). Energy that is radiated from the Sun penetrates the atmosphere before being absorbed by land and water. The warming of the Earth by the Sun causes changes in climate and the occurrence of natural phenomena such as sea breeze, land breeze, thunderstorms and so on. Warming of the Earth by the Sun Today Histor y in Radiation In 1936, North America was hit by a massive heat wave. The heat wave claimed almost 5 000 lives and it was one of the worst in the world. Figure 9.5 Radiation from the Sun to the Earth A ctivity 9.2 21st Aim: To discuss heat flow in natural phenomena. Century Instruction 1. Work in groups. 2. Gather information on heat flow that can be observed in natural phenomena such as land breeze, sea breeze and warming of the Earth by the Sun. 3. Present your discussion. 9.2.2 209 Sea breeze Warm air rises Cold air moves downwards Figure 9.6 Sea breeze The formation of land breeze and sea breeze are examples of a natural convection process. During the day, the Sun heats up the land faster than the sea. Warm air on land expands, becomes less dense and rises because it is lighter. The cold air from the surface of the sea that is more dense is drawn in to replace the warm air on land. This results in sea breeze (Figure 9.6). Land breeze Cold air moves Warm air rises downwards Figure 9.7 Land breeze At night, the land cools faster than the sea. The air above the sea which is warmer becomes less dense and rises. The cold and more dense air from land begins to move to the sea resulting in land breeze (Figure 9.7). 210 Chapter 9 : Heat Heat Conductors and Heat Insulators The base of an iron is made of metal to enable it to conduct Materials that allow heat flow are heat so that clothes can be known as heat conductors. ironed quickly. Mercury in thermometers The bottom of a pan is made of is a good heat conductor. metal that allows heat to flow It can detect change in quickly to the food. temperature very quickly. Photograph 9.3 The uses of heat conductors in daily life Materials that prevent heat Oven gloves that are flow are known as heat heat insulators can insulators. prevent your hands from getting scalded while taking food trays out from the oven. The wall of an ice box Cooking utensils made of wood are is made of fibreglass or capable of preventing heat from polystyrene, which are heat flowing to the hand while cooking. insulators that can maintain the coolness of substances inside the box. Photograph 9.4 The uses of heat insulators in daily life A ctivity 9.3 21st Century Aim: To discuss the uses of various heat conductors and heat insulators in daily life. Instruction 1. Work in groups. 2. Gather information and photographs related to various uses of heat conductors and heat insulators in daily life. 3. Present your discussion using a mind map. 9.2.3 211 Experiment 9.1 Aim: To study the uses of different materials as heat insulators. Problem statement: Which is a good heat insulator, cotton, felt or aluminium foil? Hypothesis: Cotton and felt are good heat insulators. Variables: (a) Constant variable: Volume of water in the flat-bottom flasks (b) Manipulated variable: Types of insulators (c) Responding variable: Final temperature Materials: Cotton, felt, aluminium foil and boiling water Apparatus: Flat-bottom flask, rubber stopper, thermometer and stopwatch Procedure: 1. Prepare four flat-bottom flasks as shown in Figure 9.8. 2. Record the initial temperature of each flask. 3. Record the final temperature of each flask after 10 minutes. Thermometer Thermometer Boiling water Boiling water Flat- Flat- bottom bottom K flask L M flask N Not Covered Covered with Covered with covered with cotton felt aluminium foil Observation: Figure 9.8 Flat-bottom flask K LM N Initial temperature (°C) Final temperature (°C) Difference in temperature (°C) Conclusion: Is the hypothesis accepted? Give your reasons. Questions 1. State an inference for the observation made for flask N. 2. What is the use of flask K? Thermal Equilibrium Two objects which are in thermal contact can exchange heat energy between them. The heat energy is transferred from the object with a higher temperature to the object with a lower temperature. When there is no net transfer of heat energy between the objects, the objects are said to be in thermal equilibrium. Two objects that are in thermal equilibrium have the same temperature. 212 Chapter 9 : Heat Formative Practice 9.2 1. Why is the heating coil in an electric kettle placed at the bottom of the kettle? 2. The chicken that we roast in an oven is usually wrapped in an aluminium foil. Why? 3. Why is a polystyrene container used to store ice cubes? 4. Amirah uses a thick blanket for sleeping during cold weather. What is the function of the blanket? Explain your answer. 9.3 Principle of Expansion and Contraction of Matter Expansion and Contraction of Matter Y ou have learned the three states of matter in Form One. Do you know the effect of changes in temperature towards matter? Let us carry out Activity 9.4 to study the effect of heat on the states of matter. A ctivity 9.4 Aim: To show that heat can cause solid, liquid and gas to expand and contract. A Solid SafPerteycaution Apparatus: Bunsen burner, gauge and metal bar Instruction Be careful when handling a 1. Try to fit the metal bar into the gauge (Figure 9.9). hot metal bar. 2. Heat the end of the metal bar using a Bunsen burner for Gauge five minutes. Metal bar 3. Try to fit the hot metal bar into the gauge. Record your observation. 4. Let the metal bar to cool and try to fit it into the gauge again. Record your observation. B Liquid Figure 9.9 Materials: Coloured water, ice cubes and hot water Glass tube Apparatus: Conical flask, basin, rubber stopper and glass tube Instruction Rubber 1. Set up the apparatus as shown in Figure 9.10 and mark the coloured stopper Conical water level in the glass tube at the beginning of the experiment. flask 2. Place the conical flask into a basin of hot water and observe the Coloured coloured water level. water 3. Repeat steps 1 and 2 by replacing the hot water with ice cubes and record your observations. Figure 9.10 9.3.1 213 C Gas Materials: Hot water, ice cubes and balloon Apparatus: Conical flask and basin Balloon Instruction Basin Conical 1. Set up the apparatus as shown in Figure 9.11. flask 2. Observe and record the condition of the balloon after three minutes. Hot water 3. Repeat steps 1 and 2. Replace the hot water with ice cubes. Figure 9.11 Questions 1. Give an inference for your observation in Activity A. 2. Why is coloured water used in Activity B? 3. What causes the physical changes to the balloon in Activity C? The particles in a solid vibrate at a fixed position. When the solid is heated, the particles vibrate faster and move further apart from one another. This causes the volume of the solid to increase because the solid expands. Conversely, when the solid is cooled, the particles vibrate slower and move closer to one another. This causes the volume of the solid to decrease because the solid contracts. The particles in liquid and gas move freely. When the liquid and the gas are heated, the particles move faster and randomly. The distance between the particles also increases. This causes the volume of the liquid and the gas to increase because the liquid and the gas expand. Conversely, when the liquid and gas are cooled, the particles move slower and closer to one another. This causes the volume of the liquid and the gas to decrease because the liquid and the gas contract. The Uses of Expansion and Contraction of Matter in Daily Life (a) (b) Gap Mercury Photograph 9.5 Figure 9.12 Mercury in a thermometer is a heat conductor Railway tracks have small gaps between their that can expand and contract (Photograph 9.5). rails to enable them to expand in hot weather. Without these gaps, the tracks will buckle and (c) overlap (Figure 9.12). Gap Fixed Steel bridges are built with rollers and a gap on one end. This end allows the bridges to expand in hot weather (Figure 9.13). Roller Figure 9.13 214 9.3.2 Chapter 9 : Heat (d) A bimetallic strip is usually used in devices that depend on temperature regulation. The strip is made from two different types of metal strips that can expand and contract at different rates. The fire alarm system shown in Figure 9.14 is designed with a circuit which is incomplete at room temperature. Copper When the circuit is exposed to heat from a fire, the copper strip will expand faster than the steel strip. This cause the strip to bend towards the contact point. This completes the circuit system and causes the alarm to ring. Iron Room temperature Heated Fire alarm Fire alarm SCAN Cooled Contact Battery rings IMAGE point Animation of the Fire Alarm System Bimetallic Fire strip Figure 9.14 Model of a fire alarm system The Uses of the Principle of Expansion and Contraction of Matter to Solve Simple Problems Situation 1 Try submerging the bottle lid in hot water This bottle lid is for a few moments. very tight. Then, the lid will expand and you can open it easily. Situation 2 Put the ball in a Wow, that’s This is the use of the principle basin of hot water. great! of expansion of matter. Heat Teacher, the table tennis ball causes the air in the table tennis ball to expand. is dented. 215 Formative Practice 9.3 1. What happens to the volume of water when it is heated? 2. Explain briefly why electric transmission cables on poles are hung loosely. 3. Will the expansion and contraction of matter be harmful to the structure of buildings? Give your opinion. 9.4 Relationship between Types of Surface of Object, and Heat Absorption and Emission Absorption and Radiation of Heat Have you ever wondered why fuel tanks are painted in bright colours such as white or silver? This is because bright colours do not absorb a lot of heat, therefore the evaporation of fuel is reduced. The ability of an object to absorb or radiate heat depends on the type and colour of its surface. Photograph 9.6 Fuel tank truck Experiment 9.2 Aim: To study how a dark object absorbs and radiates heat better than a white object. Problem statement: Do dark objects absorb and radiate heat better than white objects? Hypothesis: Dark objects absorb and radiate heat better than white objects. A Good heat absorber Variables: Video Video of Good Absorber (a) Constant variable: Distance from the heat source and Radiator of Heat (b) Manipulated variable: Colour of surface http://bukutekskssm.my/ (c) Responding variable: Increase in temperature Science/Video3.mp4 Materials: Black paint and white paint Apparatus: Bunsen burner, thermometer, empty milk can, iron plate, wire gauze, tripod stand and wooden block 216 9.4.1 9.4.2 Chapter 9 : Heat Procedure: 1. Prepare two empty milk cans, one painted in white and the other in Thermometer Bunsen Thermometer black. Then label the cans as J Iron plate burner Iron plate and K. Milk can Milk can Wooden block painted in painted Figure 9.15 black 2. Set up the apparatus as shown in in white Wire gauze Figure 9.15 by placing both cans as close as possible to the Bunsen Wire J K Tripod burner. gauze stand 3. Record the initial temperature of Tripod the air inside each can and light up stand the Bunsen burner. 4. Observe and record the final temperature of each can after 10 minutes. Observation: Can Temperature (°C) Increase in temperature (°C) Initial Final J K Conclusion: Is the hypothesis accepted? Give your reasons. Questions 1. Which can absorbs heat better? 2. What inference can you make from this activity? B Good heat radiator Variables: (a) Constant variable: Volume of hot water (b) Manipulated variable: Colour of surface (c) Responding variable: Decrease in temperature Materials: Black paint, white paint and hot water Apparatus: Thermometer, empty milk can, iron plate and wooden block Procedure: Iron plate Thermometer Iron plate 1. Prepare two empty milk cans, one Milk can Milk can painted in Hot water painted in painted in white and the other in white black black. Then label the cans as J and K. J 2. Fill both cans with hot water as Wooden block K shown in Figure 9.16. Figure 9.16 3. Record the initial temperature of the water inside each can. 4. Observe and record the final temperature of each can after 10 minutes. 217 Observation: Temperature (°C) Decrease in temperature (°C) Can Initial Final J K Conclusion: Is the hypothesis accepted? Give your reasons. Questions 1. Which can radiates heat better? 2. What inference can you make from this activity? 3. What method of heat flow causes the cans to lose heat? 4. Design an experiment to study whether a dull or shiny object absorbs and radiates heat better. When an object absorbs heat, its temperature increases. However, when an object radiates heat, its temperature decreases. Dark and dull surfaces are better heat absorbers and radiators compared to white and shiny surfaces. Heat Concept in Daily Life The Green Building Concept is an idea developed to reduce the effects of rapid development on the environment and our health. The features of green buildings are listed below:  has high energy efficiency through the usage of solar energy or renewable energy.  has good water flow system, air circulation and lighting.  uses recycled materials. A ctivity 9.5 S T E M 21st Century Project based learning Design a Green Home where energy used for cooling the house Green Building Concept or vice versa can be reduced. You can design or innovate in a https://www.gbcsa.org.za/ local or global context. about/about-green-building/ Info Formative Practice 9.4 1. What is the benefit of wearing bright coloured clothing in hot weather? 2. What is the feature of the wall of a thermos flask that allows it to maintain the temperature of hot water for a long time? 3. State two good heat absorbers and radiators that can be used in our daily life. 218 9.4.3 Summary Heat Relationship with temperature Uses in Expansion Effects on Heat transfer Types of surface of Heat absorption daily life Contraction matter through object Heat radiation Conduction Convection Radiation causes causes Heat conductor Heat insulator Natural phenomena Natural phenomena Uses in daily life Sea breeze Land breeze Warming of the Earth by the Sun Chapter 9 : Heat 219 Interactive Quiz 9 Quiz SELF-REFLECTION After learning this chapter, you are able to: 9.1 Relationship between Temperature and Heat Make a comparison between heat and temperature. 9.2 Heat Flow and Thermal Equilibrium Explain how heat flows from a hot region to a cold region. Explain and communicate about heat flow in natural phenomena. Communicate about heat conductors and heat insulators and their uses in daily life. 9.3 Principle of Expansion and Contraction of Matter Explain how heat can cause the expansion and contraction in solid, liquid and gas. Communicate about the various uses of expansion and contraction of matter in daily life. 9.4 Relationship between Types of Surface of Object, and Heat Absorption and Emission Demonstrate how dark, dull objects absorb heat better than white, shiny objects. Demonstrate how dark, dull objects radiate heat better than white, shiny objects. Conceptualise and design using the heat concept in daily life. Summative Practice 9 XYZ 123 1. Figure 1 shows a car at a parking lot exposed to sunlight. The Figure 1 windscreen of the car cracks the moment the air conditioner is turned on. (a) Explain the phenomenon shown in Figure 1. (b) Suggest and explain a precautionary step that should be taken to prevent this incident. 2. Keep away from heat or fire! The warning above is seen on a can of insecticide. Discuss what might happen if the empty can of insecticide is thrown into a rubbish dump. 220 Chapter 9 : Heat 3. How can you prove that heat transfer by radiation does not need a medium? Give a brief explanation. 4. (a) What causes convection current? (b) Which heat transfer method is the fastest? Explain your answer. HOTS Mastery 9 5. Cold weather on a rainy day causes Dayah to have difficulty in sleeping. She uses one thick blanket but still feels cold. Suggest a design of a blanket that can solve this problem (use the heat-trapping concept). 6. Figure 2 shows the apparatus of an experiment to study transmission of heat. Thermometer Polystyrene cover Boiling water Beaker Wooden block Figure 2 After the apparatus is left for 10 minutes, the reading of the thermometer was at 60°C. Suggest and explain modifications that need to be made to the arrangement of the apparatus so that the temperature of water reaches room temperature quickly. 221 Cha pter 10 Sound Waves Can sound waves propagate to the bottom of the sea? How do our ears respond to sound? What is echo? What is the limitation of a human’s hearing? Let’s understand: Characteristics of sound waves Loudness and pitch of sound Phenomena and applications of reflection of sound waves 222 CBhaabpt1e0r :10Ge:loSmobuanndgWBauvneysi Science Blog SCIENCE BLOG Lightning and Thunder Lightning is a phenomenon caused by huge discharge of static electricity in the sky. The static electricity passes through the air and causes the air particles to vibrate. The vibrations are heard as thunder. Have you noticed that we see the flash of lightning before hearing the rumble of thunder? In reality, lightning and thunder occur at the same time but the different speeds of propagation of light and sound through the air cause the delay. The light from the lightning travels to our eyes much quicker than the sound from the thunder. Therefore, the flash is seen before the rumble is heard. Keywords Vibration Echo Medium Pitch Wave Ultrasound Amplitude Limit of hearing Frequency Sonar 223 10.1 Characteristics of Sound Waves Our surroundings are filled with a variety of sounds. Sound is a form of energy caused by vibration. For example, the musical instruments in Photograph 10.1 produce sound through vibration. Touch the front of your throat with your fingertips while speaking. Can you feel the vibration of your vocal cords? Photograph 10.1 Musical instruments Let us carry out Activity 10.1 to study the characteristics of sound waves. A ctivity 10.1 Figure 10.1 Bell jar Aim: To study the characteristics of sound waves. Alarm clock Polystyrene A Propagation sheet (i) Requires a medium to propagate To vacuum Apparatus: Bell jar, polystyrene sheet, alarm clock and pump vacuum pump Instruction 1. Set up the apparatus as shown in Figure 10.1. 2. Activate the alarm clock and listen to the sound produced. 3. Then, turn on the vacuum pump to suck the air out. 4. Record your observation. 224 10.1.1 Chapter 10 : Sound Waves (ii) Propagate at different speeds in different medium SafPerteycaution Materials: Water and flour Apparatus: Plastic container and alarm clock Ensure the water and flour are fully filled into the Instruction containers so that there is 1. Prepare three plastic containers that are filled with air, water and no trapped air. flour respectively. 2. Place the empty plastic container (filled with air) tightly onto the table and place your ear onto the container (Figure 10.2). 3. Ask your friend to activate the alarm clock at the end of the table and listen to the sound produced. 4. Repeat steps 2 and 3 using the containers filled with water and flour. Compare the loudness of the sound produced. Plastic container filled with air Figure 10.2 Questions 1. What is observed when the vacuum pump is turned on? Give an inference for your observation. 2. Arrange the containers filled with air, water and flour in order of increasing loudness. B Sound can be reflected and absorbed Apparatus: Cardboard tube, analogue stopwatch, plasticine, wooden plank, metal sheet, softwood and towel Instruction Softwood 1. Set up the apparatus as shown in Figure 10.3 and make sure there is a distance of about 5 cm between the wooden plank and the end of the cardboard tubes. 2. Move tube Q until you can hear the ticking Wooden stopwatch clearly. Plasticine plank 3. Without moving tubes P and Q, replace the wooden P Q plank with a metal sheet followed by a towel. cardboard cardboard Compare the loudness of the ticking of the stopwatch. tube tube 4. Record all your observations. Questions Analogue 1. Based on your observation, which surface is a stopwatch (a) good absorber of sound? Figure 10.3 (b) good reflector of sound? 2. Predict whether a glass sheet is a good absorber or reflector of sound. 225 Transfer of Sound Figure 10.4 Transfer of sound from bell to the ears of the listener Sound requires a medium to propagate. Sound can propagate through a liquid, solid and gas, but not through vacuum. For example, when a bell is rung, the metal surface of the bell will vibrate. Air molecules near the surface will also vibrate and collide with the air molecules nearby. This vibration is transferred from one molecule to another molecule beside it in the form of waves. In this way, the bell produces sound that can be heard by the ears of the listener (Figure 10.4). Speed of transfer of sound in solids Speed of transfer of sound in liquids Speed of transfer of sound in gases Figure 10.5 Sound propagates at different speeds in different media 226 Chapter 10 : Sound Waves Photograph 10.2 Sound of the aircraft engines can be heard because sound can propagate through air Sound is transferred very rapidly in solids. When the particles at one end of the solid start to vibrate, the vibration causes the nearby particles to also vibrate as the particles of solids are arranged very closely together. The loose arrangement of particles in liquid causes sound vibrations to be transferred less rapidly compared to solids. Sound waves propagate very slowly in gases because the arrangement of gas particles which are far apart from each other causes a delay in transfer of vibration. 227 Reflection and Absorption of Sound Sound can be reflected and absorbed when it hits the surface of an object. These characteristics are the same as the characteristics of light that you have learned in Form One. The amount of sound reflected or absorbed depends on the surface of the object. Hard and smooth surfaces are good sound reflectors. (Photograph 10.3) Marble tiles Wall Photograph 10.3 Examples of good sound reflectors Soft and rough surfaces are good sound absorbers (Photograph 10.4) Carpet Softboard Photograph 10.4 Examples of good sound absorbers Formative Practice 10.1 1. State four sources of vibration that produce sound. 2. Tick (3) the correct statement regarding sound waves. (a) Sound waves can only be reflected. (b) Astronauts can hear sounds more clearly in the space than on Earth. (c) Sound waves require a medium to propagate. 3. The walls of cinema halls are usually covered with layers of thin softboards. What is the purpose of these boards? 228 Chapter 10 : Sound Waves 10.2 Loudness and Pitch of Sound Our ears can differentiate the sounds that are heard because sounds have different strengths and pitches. The strength or loudness of sound produced depends on the amplitude of the sound wave (Photograph 10.5), whereas pitch of sound depends on the frequency of the sound produced (Photograph 10.6). Frequency is measured in the unit of hertz (Hz). The mooing of a cow is a low The squeaking of a rat is a high Photograph 10.5 The way we press frequency sound. frequency sound. the piano keys determines the strength of the sound produced Photograph 10.6 Animals produce sounds with different frequencies What is the effect of amplitude and frequency on the loudness and pitch of sound respectively? Let us carry out Activity 10.2 to investigate these effects. A ctivity 10.2 Aim: To study the effect of amplitude on the loudness and the effect of frequency on the pitch of sound. Apparatus: Cathode Ray Oscilloscope (C.R.O.), audio signal generator, loudspeaker and connecting wire Instruction 1. Arrange the apparatus as shown in Figure 10.6. 2. Adjust the audio signal generator and C.R.O. until sound is produced and the waveform can be observed on the screen of the C.R.O. Loudspeaker Audio signal 3. Fix the frequency of the audio signal generator generator and gradually increase the C.R.O. output power. 4. Listen to the sound produced and observe the waveform on the screen of the C.R.O. Record your observation. 5. Then, fix the output power of the audio signal Figure 10.6 generator and gradually increase the frequency. 6. Listen to the sound produced and observe the waveform on the screen of the C.R.O. Record your observation. 10.2.1 229 10.2.2 10.2.3 Observation Adjustment done on audio Change in the waveform on Change in the sound signal generator C.R.O. produced by the loudspeaker Output power Frequency Amplitude Frequency Increased Fixed Fixed Increased Questions 1. What are the conclusions that can be made regarding the effect of (a) amplitude on loudness? (b) frequency on the pitch of sound? 2. Explain the relationship between the increase in amplitude and the changes in the sound produced with reference to vibration energy. 3. If an object produces vibration at a high amplitude and frequency, what will happen to the sound produced? Based on Activity 10.2, we can summarise the relationship between, loudness and amplitude; pitch of a sound and frequency as shown in Figure 10.7. Amplitude Increase in • Wave amplitude output power increases Time Increase in • Louder sound is produced Loudness frequency • Wave frequency and Pitch increases of Sound • Higher pitch is Info produced Figure 10.7 Display on screen of C.R.O. when output power and frequency are changed A ctivity 10.3 21st Century Aim: To search for information regarding the strength and pitch of musical instruments. Instruction Science 1. Work in groups. 2. Gather information regarding the following musical instruments: Amplitude (i) piano (iii) guitar 1 second (ii) recorder (iv) drum 3. Gather the following information: Frequency (a) audio recordings (b) waveform of every sound produced by the musical instruments (c) comparison between the waveforms of each musical instrument 4. Present your discussion in the form of a multimedia presentation. 230 10.2.4 Chapter 10 : Sound Waves Doppler Effect The Doppler effect is the apparent change in frequency caused by the relative movement of sound source, the relative movement of the observer or both. Figure 10.8 explains the Doppler effect. Frequency of an ambulance siren heard by Frequency of the ambulance siren heard by the observer increases when the ambulance the observer decreases when the ambulance approaches the stationary observer. drives away from the stationary observer. Figure 10.8 The Doppler effect A ctivity 10.4 21st Century Aim: To study the Doppler effect of sound using an air horn. Apparatus: Air horn Instruction 1. You are required to stand in the middle of the assembly area. 2. Ask your friend to sound an air horn while running past you. 3. Record the pitch of the sound of the air horn during and after your friend has run past you. Questions 1. What happens to the pitch of the sound when the air horn is sounded while passing by the observer? 2. State the relationship between the frequency of sound and the distance of the sound source from the observer. 3. Does the person who carries the sound source also feel the change in the pitch of the sound? Give a reason. Formative Practice 10.2 1. State one difference in the characteristics of the vibration of the voice box of men and women. 2. If a musician plays a soft note, what is the characteristic that has been changed? (a) Loudness Amplitude (a) (b) Pitch of sound 3. Figure 1 shows several waveforms formed in 0 (b) one second. Which waveform has the lowest (c) frequency? (d) (e) Time (second) Figure 1 10.3.1 231 10.3 Phenomenon and Application of Reflection of Sound Waves Reflection of sound waves is one of the characteristics of sound waves that you have learned in 10.1. This characteristic produces a phenomenon known as echo. Apart from that, reflection of sound waves is also used in various devices and sectors. Phenomenon of Reflection of Sound Waves Direction of the original wave An echo is produced when sound waves are reflected from a hard surface to the listener. The reflected echo sounds the same as the original sound but takes some time to reach Hard the listener’s ears. An echo can be heard in surface places like enclosed halls, empty rooms, caves, tunnels and gorges. Observe Figure 10.9 to understand the phenomenon of echo. Echo Original Direction wave of the echo Figure 10.9 Echo formed in an empty room Application of Reflection of Sound Waves The reflection of different sound waves can be produced when sound waves hit different surfaces. The recorded reflections will provide a variety of information and images that can be used in different sectors. Ultrasound is a type of sound wave with a frequency of more than 20 000 Hz. An ultrasound cannot be heard by humans but can be heard by animals such as bats that use it for navigation (Figure 10.10). A sound reflection technology known as sonar is used in the shipping industry to detect underwater objects. This technology is also used in other sectors such as medical and fisheries. Scan the QR code below to learn more about sonar and its uses in the medical sector. Sonar http://www.dosits.org. tutorials/technology/sonar/ Info Video Sonogram Video http://bukutekskssm.my/ Science/Video4.mp4 Figure 10.10 10.3.2 232 Chapter 10 : Sound Waves A ctivity 10.5 21st Century Aim: To gather information regarding different applications of the reflection of ultrasound. Instruction 1. Work in groups. 2. Gather information regarding different applications of the reflection of ultrasound in (a) shipping sector (c) medical sector (b) fishery sector (d) estimation of distance by bats 3. Present your discussion in the form of a multimedia presentation. Limitations of Hearing Science The frequency of sound that can be detected by humans is within Animal Hearing the range of 20 Hz to 20 000 Hz. This range becomes narrower as range (Hz) we age because our ears lose their sensitivity to sound frequencies. Bats 2 000 – On the other hand, animals have their own limit of hearing. Dogs 110 000 Bats, dolphins and dogs are examples of animals that have a higher Dolphins range of hearing than humans. Elephants 67 – 45 000 The limited sense of hearing in humans makes us unable to 40 – hear soft sounds and sounds from a distance. Therefore, we need to 100 000 use special devices to overcome these limitations (Photograph 10.7). 16 – 12 000 Stethoscopes help doctors listen to a patient’s heartbeat. Horses 55 – 33 500 A megaphone amplifies the voice so that it can be heard from a distance. Hearing aids can amplify sound entering the ear. Photograph 10.7 Devices to overcome human limitations of hearing Formative Practice 10.3 1. Does the distance of a sound source from the reflecting surface have any effect on the echo produced? Give your opinion. 2. Why is echo heard repeatedly in a cave? 3. State two uses of ultrasound. 10.3.3 233 10.3.4 234 Summary Amplitude Loudness and Sound waves Limitations of Humans Ways to overcome Loudness pitch hearing Animals limitations of hearing Frequency Pitch characteristics hertz (Hz) Can be reflected Can be absorbed Doppler reflected absorbed effect Needs a medium effectively by effectively by Solid Liquid Gas Hard and smooth Soft and rough surface surface Different speed in Phenomenon of Application of reflection of different medium reflection of sound sound waves waves Shipping sector Echo Fisheries sector Medical sector Estimation of Interactive Quiz 10 distance by bats Quiz Chapter 10 : Sound Waves SELF-REFLECTION After learning this chapter, you are able to: 10.1 Characteristics of Sound Waves Communicate the basic characteristics of sound waves. 10.2 Loudness and Pitch of Sound Explain frequency and its unit, and amplitude of vibration. Relate frequency to pitch. Relate amplitude to loudness. Explain with examples loudness and pitch using musical instruments. Doppler effect. 10.3 Phenomena and Application of Reflection of Sound Waves Explain with example the phenomena related to reflection of sound waves such as echo. Explain with example the applications of reflection of sound waves. Elaborate and communicate the limitations of hearing for humans and animals. Explain with examples ways to overcome human limitations of hearing. Summative Practice 10 1. Figure 1 shows Aiman trying to communicate with Sam at a distance of 10 metres. 10 metres Aiman Figure 1 Sam Suggest a method so that Sam can hear Aiman’s voice more clearly. 235 2. Figure 2 shows the original waveform of a sound signal on a C.R.O. screen. Draw the resulting waveform when the following adjustments are made to the sound signal. Figure 2 (a) Output power is reduced (b) Frequency is increased 3. The speed of sound waves will change when travelling through different media. State the relationship between the speed of sound and temperature of air. Explain your answer. 4. Mr. Azli moved into a new house that has no furniture. He found that echo is produced when he speaks. The effect of echo becomes lesser when furniture is brought into the house. (a) How is echo produced? (b) Why does the effect of echo reduce when there is furniture in the house? 5. Figure 3 shows ultrasound waves being used to scan the Scanning probe condition of a foetus in the womb. (a) Explain how ultrasound can be used to produce the image of the foetus in the womb. (b) Give two advantages of using ultrasound compared to X-ray. (c) Give two other uses of ultrasound waves. 6. What are the changes that can be observed if Figure 3 (a) a guitar string is tightened? (b) a guitar string is plucked harder? HOTS Mastery 10 7. You have been assigned to design a recording studio. Explain the modifications to the studio that should be done so that sound recordings of good quality are produced. 8. Astronauts communicate with each other in space using radio frequency communication equipment. Suggest and explain another way for astronauts to communicate with each other. 236 4 Earth and Space Exploration How do humans explore the Earth and the outer space? to WexhpaltoraereththeeEtaertchhnaonldogthieesouusteedr by humans space? Acarepatbhleereofasnuypoptohretrinpglalinfeet?s in the solar system Wmheatet owrooiudl,dahsateprpoeidn to the Earth if it is hit by a or comet? 237 Cha pter Stars and Galaxies 11 in the Universe What do galaxies mean? Where is our solar system located? How do the formation and death of stars happen? How do the stars in space differ from each other? Let’s understand: Stars and galaxies in the universe 238 Chapter 11 : Stars and Galaxies in the Universe Science Blog SCIENCE BLOG Supernova Explosions Do you know about Supernova? Supernovae are giant explosions of massive stars. Every explosion produces 100 times more amount of light energy than the Sun. The last supernova happened about 400 years ago but it was only detected in 1987. This supernova was visible to the naked eye for several weeks. Keywords Galaxy The Milky Way Nebula Stars Solar system 239 11.1 Stars and Galaxies in the Universe T he universe consists of every existing thing around us. Do you know that there are many objects in space which you may have never seen or known of their existence? The study of astronomy has raised our awareness of the beauty and vastness of God's creation of the universe. My Malaysia! Dato’ Dr. Sheikh Muszaphar Shukor was the first Malaysian to venture into outer space on the 10th of October 2007. Technology plays Photograph 11.1 The Earth Science an important role in the study of outer That’s right! The invention • The Hubble space telescope of technological devices was launched on the 24th of space. helps us to get a clearer April 1990. picture about the • This telescope is so universe. powerful that it could see a coin from 725 km away! Galaxies There are millions of galaxies in the universe. What do galaxies mean? A galaxy is a set of bodies consisting of millions of stars with gas and dust particles. Galaxies come in many forms, such as spiral galaxies, elliptical galaxies and irregular galaxies (Photograph 11.2). Our solar system is situated in the Milky Way galaxy (Photograph 11.3). 240 11.1.1 Chapter 11 : Stars and Galaxies in the Universe Types of galaxies Spiral Elliptical Irregular Examples: Examples: Examples: Andromeda and Ursa Major and Small Magellanic The Milky Way Cloud and Large Messier 87 Magellanic Cloud Photograph 11.2 Types of galaxies The Milky Way THE MILKY WAY • The Milky Way is a medium large spiral galaxy. • Our solar system is located at the edge of one of the spiral arms of the Milky Way. • The Milky Way consists of approximately 200 billion stars and the Sun is one of it. Not to scale Solar System Photograph 11.3 The location of our solar system within the Milky Way galaxy 241 242 Stars How do the birth and death of stars happen? Let us study the life cycle of stars. THE LIFE CYCLE OF A STAR (NEBULAR HYPOTHESIS) Medium- Red White sized star giant dwarf Nebula Large Red Supergiant Supernova Neutron star giant star Super-large Red Supergiant Supernova Black star giant hole Figure 11.1 The life cycle of a star

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Basic science: understanding experiments

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3.1.1 The experiment

Follow Janet’s instructions in the video (or use your activity booklet [ Tip: hold Ctrl and click a link to open it in a new tab. ( Hide tip ) ] PDF) to conduct the experiment. You will need about 1 tablespoon of sugar and approximately 200 ml of water in each large glass. This sugar will act as food for your yeasts to consume.

Take care to label your glasses with which variables you’ve changed – you don’t want to get them mixed up. If the environmental conditions are suitable, the yeasts will grow and multiply quite quickly – you shouldn’t need more than 30 minutes to complete this experiment. Remember that boiling water can crack glassware, so be careful to let the water cool a bit first.

Carefully observe and record which glasses have conditions suitable for the yeasts to grow and which ones have conditions that restrict its growth.

You will have the opportunity to discuss your results in the next section.

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The Importance Of Food

Healthy & unhealthy food, 1st - 2nd , a balance diet, 8th - 9th , plant parts & their functions, university , healthy eating, kg - 3rd , energy balance.

Science Form 2 Chapter 3

1st - 4th grade.

30 questions

Introducing new Paper mode

No student devices needed. Know more

1. Multiple Choice Edit 30 seconds 1 pt Define the term 'balanced diet'. A diet containing some nutrients in the correct proportions. A diet containing most nutrients in the correct proportions. A diet containing none nutrients in the correct proportions. A diet containing all nutrients in the correct proportions.
2. Multiple Choice Edit 20 seconds 1 pt __________________ are examples of high energy high nutrient food Fruits & vegetables Chocolate & Ice cream Milk & Cheese Pancake & Maple syrup
3. Multiple Choice Edit 20 seconds 1 pt Which nutrient provides the most amount of energy per gram? Carbohydrate Fats Protein Vitamin
4. Multiple Choice Edit 30 seconds 1 pt Chicken, fish and meat contain which nutrient? Protein Carbohydrate Fats Minerals
5. Multiple Choice Edit 30 seconds 1 pt Jerry wants to build up his muscles, which food group intake he should increase ? Carbohydrates Fats Proteins vitamins

Which of the following foods is a good source of protein?

Fruit and vegetables are a good source of ?

Both of the above

Why is it not a good idea to fill up your plate with only 1 kind of food?

Having variety of food shows that the meal contans a variety of nutrients.

Food that are the same are unhealthy.

Your plate looks better with different kinds of food.

Which of the following foods is a good source of carbohydrates?

Which statement is correct?

balanced diet makes you feel good

unhealthy food is good for your body

healthy eating is bad for you

by eating healthy you can get sick with a disease that can't be cured

11. Multiple Choice Edit 30 seconds 1 pt Which component of a healthy, balanced diet helps with constipation? Fibre Fats Minerals Protein
12. Multiple Choice Edit 45 seconds 1 pt Which performers can benefit from a protein-rich diet? Tennis players, golfers Swimmers, footballers 3000m runner, long distance runner Weight lifters, Sprinters,

When choosing a food to eat, why is it important to look for the amount of added sugars in the food? Consuming a lot of added sugar...

makes food taste better

is beneficial for your heart

is a leading risk factor for many diseases

gives you wings

Based on healthy food pyramid, which food that we need to eat the most?

on the top of pyramid

in the middle of pyramid

on the bottom of pyramid

Eating too much sugary food causes,

Tooth decay

High on energy

Health probems like diabetes, heart problems and cancer.

All of the above

16. Multiple Choice Edit 30 seconds 1 pt Which of the following nutrients provides energy to the body? carbohydrates vitamins water minerals
17. Multiple Choice Edit 30 seconds 1 pt Which of the following nutrients is important for body, cell, and muscle growth and repair? vitamins fats proteins carbohydrates
18. Multiple Choice Edit 30 seconds 1 pt Which nutrient supplies the most energy per gram? carbohydrates fats protein water
19. Multiple Choice Edit 30 seconds 1 pt What is the main reason for eating a wide variety of foods? to learn the food label to provide all the nutrients you need to keep from getting bored with your diet to help improve physical fitness
20. Multiple Choice Edit 20 seconds 1 pt Elements essential for good health. e.g. Calcium, Iron, Potassium Protein Fat Minerals Carbohydrates
21. Multiple Choice Edit 20 seconds 1 pt The body uses this to dissolve and transport materials. Fats Water Minerals Vitamins
22. Multiple Choice Edit 20 seconds 1 pt Organic compounds that help our body to work properly. e.g. A, C, B, K, D Carbohydrates Metabolism Vitamins Digestion
23. Multiple Choice Edit 20 seconds 1 pt Stored energy e.g. oils, butter, margarine Fats Carbohydrates Minerals Vitamins
24. Multiple Choice Edit 30 seconds 1 pt Which of the following is NOT a nutrient? water fat fiber protein
25. Multiple Choice Edit 10 seconds 1 pt When you don't drink enough water you can become: silly hyper intoxicated dehydrated
26. Multiple Choice Edit 20 seconds 1 pt Eating foods rich in calcium can help reduce the risk of osteoporosis. True False
27. Multiple Choice Edit 30 seconds 1 pt If a person has a deficiency in vitamin C, they may have... scurvy Rickets Osteoporosis Anemia
28. Multiple Choice Edit 30 seconds 1 pt If a person has a deficiency in Calcium and causes soft bones, they may have... scurvy Rickets Osteoporosis Anemia
29. Multiple Choice Edit 30 seconds 1 pt If a person has a deficiency in Iron, they may have... scurvy Rickets Osteoporosis Anemia
30. Multiple Choice Edit 30 seconds 1 pt Water is extremely important to your health because it makes us sweat gives us energy is vital in all of the bodies major functions is helps make our blood thicker so it can carry more oxygen

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Osmosis Experiments ( CIE IGCSE Biology )

Revision note.

Biology Lead

Osmosis Experiments

Immersing plant cells in solutions of different concentrations.

The most common osmosis practical involves cutting cylinders of root vegetables such as potato or radish and placing them into distilled water and sucrose solutions of increasing concentration
The cylinders are weighed before placing into the solutions
They are left in the solutions for 20 - 30 minutes and then removed, dried to remove excess liquid and reweighed

Osmosis in Plant Tissue, IGCSE & GCSE Biology revision notes

Potatoes are usually used in osmosis experiments to show how the concentration of a solution affects the movement of water, but radishes can be used too

Water must have moved into the plant tissue from the solution surrounding it by osmosis
The solution surrounding the tissue is more dilute than the plant tissue (which is more concentrated)
Water must have moved out of the plant tissue into the solution surrounding it by osmosis
The solution surrounding the tissue is more concentrated than the plant tissue (which is more dilute)
There has been no net movement of water as the concentration in both the plant tissue and the solution surrounding it must be equal
Remember that water will still be moving into and out of the plant tissue, but there wouldn’t be any net movement in this case

Investigating osmosis using dialysis tubing

Dialysis tubing (sometimes referred to as visking tubing) is a non-living partially permeable membrane made from cellulose
Pores in this membrane are small enough to prevent the passage of large molecules (such as sucrose ) but allow smaller molecules (such as glucose and water ) to pass through by diffusion and osmosis
Filling a section of dialysis tubing with concentrated sucrose solution
Suspending the tubing in a boiling tube of water for a set period of time
Water moves from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane

An example setup of a dialysis tubing experiment

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