6.2 Food Chains and Food Webs 1. Underline the correct answers. (a) A (food chain / food web) is the feeding relationship between organisms in a habitat. (b) When there are several (food chains / food webs) within an ecosystem, the relationship between them will form a (food chain / food web). (c) Each organism in (an ecosystem / a population) is part of multiple food chains. (d) A (primary consumer / secondary consumer) is usually a herbivore that feeds directly on plants. (e) Tertiary consumers are even larger animals which feed on the (primary consumers / secondary consumers). (f) A (secondary consumer / tertiary consumer) is an animal that feeds on a primary consumer. Secondary consumers can be carnivores or omnivores. (g) All food chains start with a (producer / consumer). 2. The figure shows a food chain in a habitat. Maize plant Locust Lizard Snake (a) State the habitat of the organisms above. Maize field (b) Identify the producer and consumers in the food chain. (i) Producer: Maize plant (ii) Consumers: Locust, lizard, snake (c) Why is the organism in (b)(i) categorised as a producer? Because it makes its own food from the non-living components in its environment (d) What is the process carried out by the producer in making food? Photosynthesis (e) Which organism in the food chain is a herbivore? Locust (f) What happens if all the lizards are removed from the habitat? The number of locusts increases Extra Info Food chains and food webs i Chapter 6 Interactions Among Organisms and the Environment 99
3. The following organisms are found in a pond. Small fish Algae Stork Tadpole (a) Construct a food chain that involves all the organisms above. Algae → Tadpole → Small fish → Stork (b) Based on your answer in (a), explain the relationship between the tadpole and the small fish in controlling the population size in the ecosystem. If the number of small fish increases, then the number of tadpoles will decrease. (c) If some big fish move into the pond and eat all the small fish, what will happen to the other organisms? The number of storks will decrease. The number of tadpoles will increase and this will cause the number of algae to decrease. (d) Name one example of a decomposer in the pond. Bacteria/fungi 4. The figure shows a part of a paddy field ecosystem. Snake Frog Grasshopper Caterpillar Paddy plant Organism X (a) Suggest an example of organism X. Bird (b) How many food chains are there in the food web? Four food chains (c) State the secondary and tertiary consumers in the food web. Secondary consumers: Frog, bird (organism X) Tertiary consumer: Snake 100
(d) (i) What would happen to the number of snakes if there is a decrease in the number of frogs and organism X? The number of snakes will decrease. (ii) What would happen if all the snakes in this habitat were killed? The number of prey such as frogs and organisms X will increase. (e) Where does the primary source of energy for the survival of this community come from? The sun (f) In your opinion, which of the organisms is the most important in this ecosystem? Why? Paddy plants. They provide food directly or indirectly to all the organisms in the ecosystem. 5. The figure below shows the organisms found in a mangrove swamp. Mangrove Big fish Small fish Prawn Mangrove crab Pelican (a) List two food chains formed in the habitat. Mangrove → Mangrove crab → Small fish → Pelican Mangrove → Small fish → Big fish → Pelican (b) Construct a food web based on the figure above. Mangrove crab Small fish Big fish Mangrove Pelican Prawn Chapter 6 Interactions Among Organisms and the Environment 101
(c) State the primary consumers in the food web. Prawn, mangrove crab, small fish (d) State one difference between a food chain and a food web. A food chain is a basic network that shows the linear flow of nutrients and energy from one trophic level to another. A food web is a complex network of many food chains that are linked together at many trophic levels. (e) Predict what will happen to the animals if the mangrove forest is cleared for building a new port. The animals will have no food to eat and they will all die or migrate elsewhere. 6. The figure shows the pyramid of energy. Eagles Snakes Rats Paddy plants (a) Draw an arrow on the figure above to show the energy flow. (b) Which level of the pyramid of energy has the (i) lowest energy? The highest level (ii) highest energy? The lowest level (c) Identify the organisms that are most abundant. Paddy plants (d) When energy flows from one trophic level to the next in an ecosystem, only 10% of the energy will be passed on. Based on the statement above, if the paddy plants in a food chain produce 1000 kcal of energy, how many kcal are theoretically available to the snakes and eagles? Snakes: 10 kcal of energy Eagles:1 kcal of energy (e) What energy is lost in a food chain? Heat 102
(f) When compared to the energy produced by the producer, the amount of energy left for the organisms at the end of the food chain is very small. Why? This is because energy is used for life processes such as growth, respiration, reproduction, excretion and movement. Therefore, the more trophic levels in a food chain, the more energy will be used up and very little energy will be left for the organisms at the end of the food chain. 7. The following organisms can be found in a forest community. Lion Grass Fox Rabbit (a) Construct a food chain to show the feeding relationships among organisms within the community. Grass → Rabbit → Fox → Lion (b) Draw a pyramid of numbers for this food chain. (c) Which trophic level of the pyramid of numbers has the (i) least organisms? The highest trophic level (ii) most organisms? The lowest trophic level (d) Fill in the blanks with the correct answers. (i) A pyramid of numbers can be used to show the total number of individual organisms at each trophic level in the food chain of an ecosystem. (ii) In a pyramid of numbers, the first trophic level is occupied by the producers , the second trophic level is occupied by the primary consumers, the third tropic level is occupied by the secondary consumers and the fourth trophic level is occupied by the tertiary consumers. (iii) When an organism feeds on another organism, energy is transferred. The flow of energy passes from the producers to the consumers and then to the decomposers in the food web. Chapter 6 Interactions Among Organisms and the Environment 103
8. A balanced ecosystem is created by the interdependence of living organisms and the environment. Which of the following statements shows a balanced ecosystem? Tick (✓) the correct answer. The population of consumers is larger than the population of producers. ✓ The organisms and their environments are in a harmony without external interference. ✓ The size of each population remains constant because there is a continuous supply of basic needs. When some species die suddenly, other new species are introduced into the ecosystem. 6.3 Nutrient Cycles in an Ecosystem 1. (a) Complete the carbon cycle below using the words given. Open burning Photosynthesis Decomposiion Combustion Respiration Carbon dioxide in the air Open burning Respiration by plants by green plants Photosynthesis Respiration by animals Respiration by aquatic animals Photosynthesis by aquatic plants Combustion of fossil fuels of dead organisms and waste products Decomposition (b) What type of organisms absorbs the most carbon from the atmosphere? Plants (c) How do humans return carbon to the atmosphere in the carbon cycle? Respiration 104
2. (a) Complete the nitrogen cycle below using the words given. Ammonification Nitrifying bacteria Lightning Nitrogen-fixing bacteria Denitrification Assimilation BAJA Atmospheric nitrogen (N2) Fertilising activities Nitrates Nitrites Ammonia and ammonium Bacteria and fungi Animal Faeces Plant Assimilation (Nitrate is absorbed by plants) Denitrification by denitrifyng bacteria Nitrogen-fixing bacteria Nitrification by nitrifying bacteria live in root nodules of legumes Lightning Ammonification (b) Read the statements below and underline the correct answers. (i) Nitrogen in the air cannot be directly used by living things. It has to be converted by bacteria into (nitrites / nitrogen dioxide) and (ammonium / nitrates) that are easily absorbed by plants. (ii) (Nitrogen-fixing bacteria / Nitrifying bacteria) are found in the root (caps / nodules) of legumes. They convert nitrogen in the atmosphere to ammonia. (Nitrifying bacteria / Denitrifying bacteria) convert ammonia into nitrites or (nitrogen / nitrates), which is dissolved in the soil through (nitrification / denitrification). (iii) The plants absorb nitrates from the soil into their roots through (assimilation / ammonification) and convert them into nitrogenous organic compounds. (iv) After animals or plants die, the (consumers / decomposers) present in the soil convert the nitrogen compounds found in animal waste and the remains of dead plants into ammonium and (nitrates / ammonia) through (ammonification / assimilation). (v) Lightning helps convert atmospheric nitrogen into (nitrites / nitrogen dioxide), which dissolves in water to form (nitric acid / nitrates) that fall on the earth along with rain. Chapter 6 Interactions Among Organisms and the Environment 105
(vi) (Denitrifying bacteria / Nitrifying bacteria) convert nitrates in the soil to atmospheric nitrogen through (denitrification / nitrification). 6.4 Interactions between Organisms 1. Name the different types of interactions between organisms as described below. (a) A relationship in which an organism feeds on another organism. Predator-prey (b) An interaction in which an organism benefits while the other organism neither benefits nor suffers losses. Commensalism (c) An interaction in which organisms compete with each other for food, water, shelter and mates. Competition (d) A relationship in which an organism lives on or in the host and the host is harmed by it. Parasitism (e) Two organisms living and interacting with one another, both benefiting from the relationship. Mutualism 2. The figures below show examples of the different types of interactions. Name the types of interactions. (a) Shark Remora (b) Rafflesia Tree trunk Commensalism Parasitism (c) Sea anemone Hermit crab (d) Mutualism Competition (e) Tree Bird’s nest fern (f) Eagle Chick Commensalism Predator-prey 106
3. The following figure shows a type of interaction between organisms. Tiger Deer (a) Name the interaction shown in the figure and describe it briefly. Predator-prey The tiger (predator) feeds on the deer (prey) for food. (b) State two points on the importance of the type of interaction shown. Controls the size of the population of organisms Creates a balanced and stable environment (c) The figure below shows two types of interactions among organisms. Cat Fish P Q (i) Identify the types of interactions shown in P and Q. P: Intraspecific competition Q: Interspecific competition (ii) Compare both types of interactions. In P, competition for basic needs happens between organisms of the same species. In Q, competition for basic needs happens between organisms of different species. (iii) What basic needs do the forest plants compete for? Sunlight, water, nutrients, space (d) Symbiosis is another type of interaction between organisms. There are three types of symbiosis. Briefly describe each of them. Mutualism is a symbiotic relationship in which both organisms benefit. In commensalism, one organism benefits while the other is not affected. In parasitism, one organism benefits while the other is harmed. Chapter 6 Interactions Among Organisms and the Environment 107
6.5 Factors that Affect the Organisms and Environment 1. The size of the population in an ecosystem changes over time. Complete the table below about the factors affecting population size. Factor Effects on the population size Presence of predators The presence of predators decreases the size of the affected population in a given area. Diseases When there is a disease outbreak, the population size of plants and animals decreases . Source of food If there is a food shortage, animal populations will decrease and may face extinction . Climate change Extreme weather such as prolonged drought will decrease the population size of plants and animals due to a lack of food and water . 2. Read the following information about acid rain and fill in the blanks. The major cause of acid rain is air pollution from burning fossil fuels . When air pollutants such as sulphur dioxide and nitrogen dioxide dissolve in rainwater, acid rain is formed. As acid rain enters water systems, it turns the water acidic , making it unsuitable for aquatic plants and animals. It can be very harmful to plants and the soil too. Acid rain decreases the pH of the soil, causing its acidity to increase. It can also damage man-made structures such as buildings and statues. 3. Read the article below and answer the questions. Sea levels have risen by about 21 cm to 24 cm globally as a result of melting ice in the Arctic and Antarctic regions. According to recent research by Indonesia’s National Research and Innovation Agency (BRIN), it is estimated that at least 115 of Indonesia’s small islands are on the verge of sinking. This is due to rising sea levels and land subsidence. (a) What causes the ice in the Arctic and Antarctic regions to melt? Global warming (b) What gases contribute to the phenomenon in (a)? How do these gases cause it? Carbon dioxide, methane, nitrous oxide, water vapour and chlorofluorocarbon. The gases trap heat in the atmosphere and prevent heat from escaping into space, warming the earth’s surface. 108
(c) State three steps that can be taken to reduce the sea level rise due to the phenomenon in (a). Replant trees. Enforce the law to impose penalties on illegal logging. Raise public awareness by conducting campaigns. 4. Answer the following questions. (a) Ben’s vegetable garden was attacked by a type of caterpillar that eats his plants. Ben wants to use pesticides to solve this problem. Do you agree? Justify your answer. No. The excessive use of pesticides contaminates soil and water. The pesticide residues may remain in the plants, and may eventually enter the food chain, posing a threat to humans. (b) A factory has discharged hot water into a nearby river. State an effect on the plankton population in the river. The plankton population dies. Plankton needs an average temperature to continue to survive. 5. Complete the multi-flow map about the ways to reduce water pollution. Use proper methods to dispose of old medications . Use phosphate-free detergents and soaps. Properly dispose of chemicals . Have proper sewage treatment programmes and management. Use the action of microorganisms as a biological treatment to treat contaminated water. Minimise the use of pesticides , herbicides and fertilisers. Use organic approaches to control pests and weeds. Do not throw rubbish and plastic into the water. Do not pour fats, grease and oils down the sink. Ways to reduce water pollution Chapter 6 Interactions Among Organisms and the Environment 109
Objective Questions A B C D Choose the best answer. 1. Which of the following is true about an ecosystem? I There are more carnivores than herbivores. II All organisms depend on each other. III There are many interconnected food chains. IV It comprises only biotic components. A I and II only B II and III only C II, III and IV only D I, II, III and IV 2. The figure shows a food chain in a certain habitat. P Q Crocodile What is the immediate effect if all the crocodiles were removed from the habitat? A The population of organism P will increase. B The population of organism Q will increase. C The populations of organisms P and Q will decrease. D The populations of organisms P and Q will increase. 3. Which of the following food chains is correct? A Caterpillar → vegetable → eagle → chicken B Vegetable → caterpillar → chicken → eagle C Vegetable → chicken → caterpillar → eagle D Eagle → chicken → caterpillar → vegetable 4. The following figure shows feeding relationships in a habitat. XXXXX XXXXX V Y Y Y Y Y V V XX W W W W Z Z XXX P Q T S R Which of the following statements is not true? A The population of organism X is larger than the population of organism W. B There are three populations of organisms in ecosystem T. C Populations of organisms V and Y make up community R. D Organism Z is a consumer. 5. W, X, Y and Z are organisms in a food chain where W is a seagull, X is phytoplankton, Y is a crab and Z is a sea urchin. Which of the following sequences shows the number of organisms in the correct descending order? A W, Y, Z, X C X, Z, Y, W B X, Y, Z, W D Z, X, W, Y 6. The figure shows an interaction between a buffalo and an oxpecker. Oxpecker Buffalo 110
Which of the following pairs of organisms has the same interaction as the one shown? A Owl and mice B Aphid and ant C Tick and dog D Barnacle and whale 7. Which of the following is true about parasitic plants? I They absorb food from their host. II They provide water for the host. III They supply mineral salts to the host. IV They compete with the host for sunlight. A I only B I and II only C III and IV only D I, II and IV only 8. Which predator is most suitable to be used to reduce the population of golden apple snails in a paddy field? A Buffalo B Bird C Cat D Grasshopper 9. The figure shows a pyramid of numbers. X Which of the following may be represented by X? A Caterpillar C Frog B Grass D Eagle 10. Why do trees in tropical rainforests tend to grow very tall? A They store food in their tissues for a long time. B They have very strong prop roots. C They compete with one another for sunlight. D They compete with one another for water and mineral salts. 11. The figure shows part of the nitrogen cycle. Nitrogen Ammonium Nitrites Nitrates Process X Process Y What are processes X and Y? A X = Nitrification; Y = Assimilation B X = Ammonification; Y = Nitrification C X = Nitrification; Y = Ammonification D X = Ammonification; Y = Denitrification 12. Which of the following factors is a major cause of global warming? A Air pollution B Deforestation C Climate change D Ozone depletion Chapter 6 Interactions Among Organisms and the Environment 111
Concept Map Complete the concept map below about interactions among organisms and the environment. Producers Producers Competition • Intraspecific competition • Interspecific competition • Commensalism • Parasitism • Mutualism • Pyramid of numbers • Energy flow in a food web Symbiosis Predator-prey Community Primary consumers Secondary consumers Tertiary consumers Consumers Decomposers • Air • Soil • Water • Sunlight • Temperature • Diseases • Food shortage • Climate change • Soil pollution • Air pollution • Water pollution • Carbon cycle • Nitrogen cycle Abiotic components Nutrient cycles Food chain Food web Interactions between organisms Biotic components has forms represented in the form of types feeding relationship between are are such as is balanced through Factors that affect the organisms and environment Species Population Ecosystem 112
Types of interactions HOTS Daily Application The figure shows a pond located in Jatin’s yard. The pond is a well-managed artificial habitat that contains a variety of aquatic plants. Jatin recently discovered mosquito larvae in his pond. Based on the information given and your knowledge about the interactions among organisms, suggest one method for Jatin to eliminate the larvae from his pond. Explain your suggestion. Justify your suggestion. Rear fish in the pond. The larvae and the fish have a predator-prey interaction. The fish eat the larvae for food. This can control the population of larvae. This method is called biological control and it is affordable and eco-friendly. Online Quick Quiz Chapter 6 Interactions Among Organisms and the Environment 113
Earth and the Solar System CHAPTER 7 7.1 The Solar System 1. The table shows the characteristics of the planets in the Solar System. Planet Relative mass Diameter (km) Density (g/cm3 ) Surface temperature (°C) Earth 1 12 756 5.5 14 Mars 0.107 6794 3.9 –60 Mercury 0.055 4879 5.4 430 Venus 0.815 12 104 5.2 462 Jupiter 317.8 142 984 1.3 –108 Uranus 14.536 51 118 1.27 –197.2 Neptune 17.147 49 528 1.6 –201 Saturn 95.159 120 536 0.7 –139 (a) Which planet has the greatest mass? Jupiter (b) Which is the smallest planet in the Solar System? Mercury (c) Which is the densest planet in the Solar System? Earth (d) Which planet is almost the same size as the Earth? Venus (e) Arrange the planets according to their increasing size. Mercury, Mars, Venus, Earth, Uranus, Neptune, Saturn, Jupiter (f) Which planet is the hottest planet in the Solar System? Venus (g) Which planets are made up of gases? Jupiter, Saturn, Uranus and Neptune (h) Name the terrestrial planets in the Solar System. Mercury, Venus, Earth and Mars Extra Info Solar System i 114
2. The figure shows the arrangement of the planets in the Solar System. X Y (a) In general, what is the relationship between the surface temperatures of planets and their distances from the Sun? In general, the surface temperatures of planets decrease with increasing distance from the Sun. (Note: Venus is the exception, as its proximity to the Sun and dense atmosphere make it the hottest planet.) (b) Why are planets X and Y not able to support life? Planet X is Mercury. It is too close to the Sun, extremely hot and dry, and has very little atmosphere. Planet Y is Neptune. It is extremely cold. It is not conducive to life due to its freezing temperatures. (c) Which planet can support life? Why? Earth. It is located at the right distance from the Sun. It has the characteristics that support life such as the presence of air, water and carbon with the right atmosphere and temperature. (d) Assume that the distance between the Earth and the Sun is reduced to half of its present distance. What is the most likely to happen to life? Life may no longer exist. Some environmental conditions are not met for the existence and continuation of life including high temperatures and the lack of water and a suitable atmosphere. 3. The table shows the time taken by five planets to orbit the Sun. Planet Time taken to orbit the Sun (time on Earth) Mars 687 days Jupiter 11.9 years Saturn 29.5 years Uranus 84 years Neptune 164.8 years Chapter 7 Earth and the Solar System 115
(a) How do the planets in the Solar System move? The planets orbit the Sun and rotate on their axes. (b) Why is the time taken by Mars to orbit the Sun shorter than that of Saturn? Mars has a smaller orbit compared to Saturn. (c) Why does each planet take a different amount of time to orbit the Sun? A planet’s orbiting time depends on how far it is from the Sun. The closer the planet is to the Sun, the less time it takes to orbit the Sun. It takes less time because the length of the orbit is shorter. So the larger a planet’s orbit, the longer the planet takes to complete it. (d) What can you say about the planets’ distance from the Sun in relation to the time it takes to orbit the Sun? The further the planet is from the Sun, the longer it will take to orbit the Sun. (e) How long does it take for the Earth to orbit the Sun? 365 days (f) If a new planet is discovered and its orbit around the Sun takes 200 years, where do you think it is in our Solar System? Beyond Neptune 4. The figure shows three planets in the Solar System. Planet X is the fourth planet from the Sun. Planet Y is the closest to the Sun. Planet Z has rings around it. X Y Z (a) (i) Name planet X. Mars (ii) What is the planet in (a)(i) known as? Give one reason why this name was given. The red planet, because it appears red due to its surface being covered in reddish sand dust containing lots of iron oxide. (b) Name planet Y. Mercury 116
(c) Which planet has no satellite? Planet Y/Mercury (d) Among these three planets, which planet is made up of gases? Planet Z/Saturn (e) What are planet Z’s rings composed of? The rings are composed of ice with small amounts of rocky material and dust. (f) Arrange the planets in ascending order of size. Planet Y (Mercury), planet X (Mars), planet Z (Saturn) 5. Match the following objects in the Solar System with their descriptions correctly. A spherical celestial body that revolves around the Sun but does not have a clear path around it Small pieces of rocks and metals formed by the debris of asteroids or comets that move around the Sun A massive sphere-shaped body that revolves around the Sun in a fixed orbit The star at the centre of the Solar System A celestial object that revolves around a larger celestial object Large rocky and metal objects that move around the Sun Rocky objects that move around the Sun and are made of a mixture of gas, ice and frozen dust Planet Dwarf planet Asteroids Meteoroids Comets Satellite Sun Chapter 7 Earth and the Solar System 117
6. There are two satellites that orbit the Earth, as shown below. Moon Earth X (a) What is a satellite? A satellite is a celestial object that revolves around a larger celestial object. (b) What type of satellite is our Moon? Natural satellite (c) What is object X? State one use of this object. Artificial satellite Used for communications or weather forecasting (Any suitable answer) 7. Answer the following questions. (a) State two differences between planets and dwarf planets. Planets are large while dwarf planets are small. Planets have clear orbits while dwarf planets do not have clear orbits. (b) The following paragraph consists of facts on Pluto. For a long time, Pluto was considered to be the ninth and smallest planet in our Solar System. However, after scientists made some new discoveries, they decided that it was not a planet. Why is Pluto not considered a planet? Pluto is a dwarf planet because it has not cleared its neighbouring region of other objects in its orbit. (c) The following information is about a dwarf planet. (i) It is the largest object in the asteroid belt of the Solar System. It was discovered by Giuseppe Piazzi on 1 January 1801. Scientists classified it as a dwarf planet in 2006. Which dwarf planet is described above? Ceres 118
(ii) This dwarf planet orbits the Sun far beyond Neptune. It was discovered in 2003 by a team of astronomers. It has an unusual egg-shaped structure. It has two moons. Which dwarf planet is described above? Haumea (d) Give two examples of dwarf planets that are located in the Kuiper Belt. Pluto, Eris, Makemake, Haumea (Any two) (e) Which dwarf planet spins on its axis so fast that its day is only four hours long? Haumea 8. The figure shows some bodies found in the Solar System. P Q R (a) Name the bodies P, Q and R. P: Asteroids Q: Meteors R: Comet (b) Most asteroids and meteoroids are pieces of rocks. Compare asteroids and meteoroids in term of their sizes. Most meteoroids are smaller than asteroids. (c) What causes meteoroids to burst into flames when they enter the Earth’s atmosphere? The friction between the air and the meteor produces heat until it burns. (d) The figure shows a phenomenon observed in the Earth’s night sky. What is this phenomenon known as? Meteor shower Chapter 7 Earth and the Solar System 119
(e) (i) What is a space rock that survives its passage through the Earth’s atmosphere and lands on the surface called? Meteorite (ii) When the space rock hits the Earth’s surface, it leaves a hollow space in the ground. What is the hollow space called? Crater 9. The figure below shows the Sun, planets and other objects in the Solar System. Asteroid belt Kuiper Belt Oort Cloud (a) Label the figure above using the following terms: Kuiper Belt Asteroid belt Oort Cloud (b) Where is the asteroid belt located? Between Mars and Jupiter (c) What is the asteroid belt made up of? It contains millions of asteroids which are made up of rocks. (d) Is the Kuiper Belt in our Solar System? Where is the Kuiper Belt? Yes, it is a region in the Solar System beyond the orbit of Neptune. (e) Where do most of the comets originate from? Kuiper Belt and Oort Cloud (f) What force keeps planets, comets, asteroids and meteoroids in their orbits around the Sun? Gravitational force 120
7.2 Earth and Its Satellite 1. Tick (✓) the correct statements. Cross (✗) the incorrect statements. (a) The Earth takes 24 hours to complete one rotation on its axis. ✓ (b) The Moon takes 365 days to complete one revolution around the Sun. ✗ (c) The Earth is tilted on its axis at an angle of 23.5° from the vertical. ✓ (d) The axis is the imaginary line that the Sun rotates around. ✗ (e) The rotation of the Earth on its axis causes day and night. ✓ (f) The Earth’s atmosphere is mostly hydrogen with plenty of carbon dioxide. ✗ (g) The side of the Earth that faces the Sun experiences daylight as it rotates. ✓ (h) A calendar year has 365 days, but a leap year has 364 days. ✗ (i) The Earth’s atmosphere protects us from incoming meteoroids, which usually break up before reaching the ground. ✓ 2. The figure shows the Earth at four different positions P, Q, R and S in its orbit around the Sun in a year. At each position, different hemispheres of the Earth will experience a different season. P Q R S (a) State all the seasons that the Earth experiences in a year. Spring, summer, autumn and winter Chapter 7 Earth and the Solar System 121
(b) What causes the seasons on the Earth? The Earth revolves around the Sun. The Earth’s axis is tilted with respect to its orbital plane, which causes the seasons. (c) Which season will the Northern Hemisphere and Southern Hemisphere of the Earth experience when the Earth is at positions P, Q, R and S, respectively? Complete the table below. Position Northern Hemisphere Southern Hemisphere P Spring Autumn Q Summer Winter R Autumn Spring S Winter Summer (d) Why do the hemispheres not have the same season at the same time? The Earth’s axis is tilted. When the Northern Hemisphere tilts towards the Sun, it experiences summer, but at the same time, the Southern Hemisphere is tilted away from the Sun and experiences winter. (e) Why does Indonesia not have distinct seasons? Indonesia is located near the equator. 3. When we view the sky at night, we may often see different shapes of the Moon throughout a month. (a) What is the phenomenon that describes the changing shapes of the Moon as seen from the Earth? Phases of the Moon (b) What causes the phenomenon mentioned in (a)? The Moon reflects sunlight while orbiting the Earth, making it as if the Moon is changing its shape when observed from the Earth at different times of a month. (c) How long does the Moon take to complete its lunar cycle? 29.5 days (d) We hardly see the Moon in the day sky. When it is in the night sky, it is visible. Why? Because it reflects the light from the Sun 122
(e) Why do we always see the same face of the Moon from the Earth? The amount of time the Moon takes to complete one rotation on its axis is similar to the time it takes to complete one revolution around the Earth. (f) What phase would the Moon be in when it is between the Sun and the Earth? New Moon (g) Each month, the whole cycle starts with a New Moon. Label other phases of the Moon in the figure below. Sunlight Sun New Moon 4. The figure below shows the occurrence of a natural phenomenon. Sun Shadow of the Earth Earth Moon X Y (a) What is this phenomenon called? Lunar eclipse Chapter 7 Earth and the Solar System 123
(b) How does the phenomenon in (a) occur? It occurs when the Earth is in between the Sun and the Moon, blocking the sunlight from reaching the Moon’s surface and casts its shadow on the Moon. (c) Which part of the Earth can see this phenomenon? It can be seen from any part of the Earth where it is night. (d) Regions X and Y are parts of the shadow of the Earth. Name them. Region X: Penumbra Region Y: Umbra (e) Identify the phenomenon that occurs when the Moon is in region X. Partial lunar eclipse (f) Identify the phenomenon that occurs when the Moon is in region Y. Total lunar eclipse (g) Describe the appearance of the Moon observed from the Earth when it is in region Y. The Moon appears to be reddish. 5. Tides occur mainly in oceans. (a) What are tides? Tides are the alternate rising and falling of the ocean in a day. (b) What causes the tides in our oceans? The gravitational force of the Moon attracts the ocean to bulge out towards it. (c) How many high tides and low tides are there each day? Two high tides and two low tides (d) (i) Why are tides especially high or low during the Full Moon and the New Moon? The Sun, Moon and Earth are in a line. The gravitational forces of the Sun and the Moon are combined, resulting in especially high or low tides. (ii) What are these tides called? Spring tides 124
(e) The figure below shows a type of tide that occurs when the Moon is in these two positions. Sun Earth (i) What type of tide occurs in the figure above? Neap tides (ii) Label the phases of the Moon in the figure above. (iii) Describe this type of tide. When the Moon is in the first quarter or the third quarter, the effects of the gravitational forces of the Sun and Moon cancel each other out. This results in a smaller difference between high tide and low tide. (f) State the importance of tides. The tides influence navigation of ships, fishing and water-related sport activities. 6. Fill in the blanks with the correct words. signals locations Earth-observation astronauts receivers (a) Global Navigation Satellite System (GNSS) is a group of satellites that transmit positioning and timing data to receivers . It is used to determine precise locations and also help in navigation. (b) Earth-observation satellites observe the Earth from space to predict the weather, improve agricultural practices, and detect forest fires and oil spills. (c) Communication satellites are designed to relay signals carrying voice, video and data to and from one or many locations worldwide. (d) The International Space Station (ISS) is an orbiting laboratory where astronauts live and work in space. Chapter 7 Earth and the Solar System 125
7.3 The Sun 1. The figure below shows the structure of the Sun. (a) Label the figure with the words given. Photosphere Radiation zone Core Prominence Convection zone Sunspots Corona Solar flare (b) What are the main gases that make up the Sun? Hydrogen and helium (c) In which layer of the Sun do sunspots form? Photosphere (d) Why do sunspots appear darker than their surrounding areas? They are cooler than their surroundings and there is less light. (e) A structure on the Sun, is a large and bright feature that extends outward from the photosphere to the corona in a ring form. What is this structure? Solar prominence (f) What is a solar flare on the Sun? A solar flare is an explosion of hot gases from the surface of the Sun that releases charged particles and is usually associated with sunspots. Extra Info The Sun i 126
(g) What phenomenon can we see when solar wind penetrates the Earth’s magnetic field? Aurora (h) How long does sunlight take to reach the Earth? About 8 minutes 2. (a) Draw a figure to show the formation of the solar eclipse. In the figure, show the correct positions of the Sun, the Earth and the Moon. (b) Describe the positions of the Sun, Moon and Earth during the solar eclipse. The Moon is between the Sun and the Earth in a straight line. (c) How does the solar eclipse occur? It occurs when the Moon moves between the Sun and the Earth, blocking the sunlight from reaching the Earth and the Moon casts a shadow on the Earth. (d) When the Moon blocks the Sun, it produces a shadow with two regions, the umbra and the penumbra. Label these two regions on the figure above. (e) What do the people experience when a total solar eclipse occurs? They will experience total darkness for a few minutes even though it is daytime. (f) What is it called when the Earth is in the Moon’s penumbra? Partial solar eclipse (g) Why should we not look straight at the Sun when the phenomenon in (f) occurs? The Sun can cause eye damage. Chapter 7 Earth and the Solar System 127
Objective Questions A B C D Choose the best answer. 1. The following information is about a planet. Unlike other planets, the Sun rises from the west on this planet. Because of the high carbon dioxide content in its atmosphere, this planet is also called as the ‘greenhouse’ planet. What is this planet? A Mars B Venus C Jupiter D Mercury 2. The following shows the average distance of four planets from the Sun. Which planet is the coldest? Planet Average distance from the Sun (million km) A P 4497 B Q 57.9 C R 1427 D S 2871 3. How would the Earth be affected if its rotation were to suddenly slows down? I Disruption in weather II The duration of day and night would be longer. III The whole Earth becomes extremely cold. A I and II B I and III C II and III D I, II and III 4. The figure shows the position of the Earth and a planet, Y in the Solar System. Earth Y What would happen if the Earth and planet Y switched position? A Planet Y will be frozen. B The Earth will get colder. C The polar ice on the Earth will melt. D The length of a day on planet Y will shorten. 5. Why is Earth the most suitable planet to sustain life? I The Earth has one moon. II The Earth is a large planet. III Water is available on Earth. IV The atmosphere of the Earth has oxygen. A I and II C II and IV B I and III D III and IV 6. Jupiter is larger than the Moon, but it appears to be smaller when viewed from the Earth. What could be the reason for this? A Jupiter is made up of gases, while the Moon is made up of rocks. B The Moon is closer to the Earth than Jupiter. C The distance of Jupiter from the Moon is closer than the Earth. D Jupiter is located further away from the Sun than the Moon. 128
7. Which of the following statements best explains why the Earth has four seasons in a year? A The Earth rotates on its axis from the west to the east. B The distance between the Earth and the Sun changes. C The Earth’s axis is tilted as it moves around the Moon. D The Earth’s axis is tilted as it moves around the Sun. 8. The figure shows the four positions of the Moon when it revolves around the Earth. Earth Sun Q R S P Which of the following statements is true? A When the Moon is at P, the phase is called as the Full Moon. B When the Moon is at Q, we can see only a very small part of the bright moon. C When the Moon is at R, we do not see the Moon. D When the Moon is at S, the Moon looks like a semicircle. 9. Why does the Moon have a stronger effect on the Earth’s tides than the Sun does? A The Moon is larger than the Sun. B The Moon has a lower mass than the Sun. C The Moon is farther away from the Earth than the Sun. D The Moon is closer to Earth than the Sun. 10. Why are some years 365 days long and others 366? A The Earth’s orbit is an ellipse rather than a perfect circle. B Even years have an even number of days, whereas odd years have an odd number of days. C The speed at which the Earth revolves varies according to the year. D The length of a year is actually 365.25 days, and as a corrective measure, a day is added every four years. 11. Read the announcement below and answer the question. The Meteorology, Climatology and Geophysics Agency (BMKG) advised residents living in coastal areas to watch out for high tides during the total lunar eclipse on 8 November 2022. People need to be aware of the occurrence of sea tides that are higher than normal. Which of the following statements best explains the relationship between the total lunar eclipse and tides? A A lunar eclipse happens when the Earth blocks the Sun’s rays from reaching the Moon. B The Moon rotates faster when the Sun, Moon and Earth are in alignment, resulting in high tides. C During an eclipse, the Sun, Earth and Moon are in a line, and the combined gravitational forces of the Moon and the Sun cause the high tides. D When the Sun and Moon are at right angles, the combined gravity is stronger producing high tides. Chapter 7 Earth and the Solar System 129
Concept Map Complete the concept map below about Earth and the Solar System. Mercury Solar eclipse Lunar eclipse Seasons Phases of the Moon Earth’s ocean tides Day and night • Spring tides • Neap tides • Global Navigation Satellite System (GNSS) • Earth-observation satellites (EOS) • Communication satellites • International Space Station (ISS) Natural satellite/Moon Inner layers Sun’s atmospheric layers Venus Earth Mars Jupiter Saturn Uranus Neptune • Core • Radiation zone • Convection zone • Solar prominence • Solar flare • Sunspots • Solar wind • Photosphere • Chromosphere • Corona • Natural satellites/Moons • Dwarf planets • Comets • Asteroids • Meteoroids, meteors, meteorites Planets Other objects Space technology phenomena that occur on the surface of the Sun has due to axial tilt due to Earth’s rotation due to the Moon’s revolution caused by the gravitational force of the Moon Sun Solar System 130
HOTS Daily Application Read the article shown below. Asteroids are rocky remnants left over from the early formation of our Solar System, which occurred about 4.6 billion years ago. Most of them can be found orbiting our Sun within the asteroid belt—a region located between the orbits of Mars and Jupiter. They come in many shapes and sizes, with the largest asteroid measuring 530 km in diameter. Asteroids can pose a threat to Earth, as demonstrated by the Chelyabinsk disaster, which occurred on 15 February 2013 when a space rock entered the Earth’s atmosphere and exploded over the southern Ural region in Russia. This event injured over 1100 people and caused nearly US$33 million in damage. Collisions between large asteroids and the Earth may cause the destruction of life and property on Earth. How can such a collision be avoided? Astronomers are always monitor the asteroids in space to ensure the asteroids are at a safe distance from the Earth. Asteroids approaching the Earth may be destroyed or have their directions changed with the aid of technology. Online Quick Quiz Chapter 7 Earth and the Solar System 131
1. Which of the following is the first step in conducting a scientific investigation? A Making a hypothesis B Planning an investigation C Identifying a problem D Identifying the variables 2. What does the following information refer to? • Looking for patterns in the data that has been collected • Explaining the patterns identified A Identifying the variables B Defining operationally C Making an inference D Analysing and interpreting data 3. The figure shows a hazard warning symbol on the label of a bottle containing chemicals. What does the hazard warning symbol mean? A Explosive C Corrosive B Flammable D Toxic 4. Which of the following unit conversions is correct? A 8 m2 = 8 × 102 mm2 B 9 kg = 9 × 105 mg C 1.7 × 104 cm2 = 1.7 m2 D 2000 cm = 0.002 km 5. Which of the following measuring instruments can be used to measure the thickness of a bowl? A Vernier caliper B Thermometer C Metre rule D Measuring cylinder 6. Which of the following is not a desirable attitude of a scientist? A Open-minded B Curious C Creative D Confident that he is always right 7. A block has a mass of 420 g and a volume of 600 cm3 . What is the density of the block? A 0.6 g/cm3 B 0.7 g/cm3 C 0.9 g/cm3 D 1.4 g/cm3 8. Azmin poured 200 cm3 of water into three different containers, P, Q and R, as shown below. P Q R What inference can be made from this activity? A Water is a liquid. B Water boils at 100ºC. C Liquids flow easily. D Liquids do not have a fixed shape. Assessment 2 Section A [40 marks] Choose the best answer. Answer all questions. 132
9. Which of the following is matched correctly? Process Change of matter A Condensation Solid → gas B Deposition Gas → solid C Freezing Solid → liquid D Melting Gas → liquid 10. The figure shows the particle arrangement in substance X at room temperature. Substance X is most probably A nitrogen gas B alcohol C wood D rock 11. 100 g of ice at 0°C is heated until it melts into water at 0°C, and the amount of heat energy required is 334 J. What is the specific latent heat of fusion of the substance (ice)? A 1.67 J/g C 3.34 kJ/g B 3.34 J/g D 6.68 J/g 12. Heat transfer by conduction occurs through A movement of a fluid B movement of air C direct contact between objects D electromagnetic waves 13. How long does it take for a car travelling at an average speed of 82 km/h to travel 205 km? A 2 hours C 3 hours B 2.5 hours D 5 hours 14. Which of the following is the main factor causing a sea breeze? A The temperature difference between the land and sea B The wind direction C The wind speed D The humidity 15. Dave drives his car along the path from P to S in 3 hours. R Q P S 50 km 60 km 136 km N What is the average speed of the car? A 41 km/h B 62 km/h C 82 km/h D 136 km/h 16. What happens when the buoyant force exerted on an object is greater than its weight? A The object will sink. B The object will float. C The object will remain at the same depth. D The object will move faster. 17. What happens to the inertia of an object when its mass increases? A Its inertia decreases. B Its inertia increases. C Its inertia remains the same. D Its inertia becomes zero. Assessment 2 133
18. If you push a wall, what happens according to Newton’s Third Law? A The wall will not push back on you. B The wall will push back on you with the same force. C The wall will push back on you with a greater force. D The wall will push back on you with a smaller force. 19. Which of the following statements is correct about biodiversity? I Biodiversity is the variety of life on Earth, including the diversity of ecosystems, species and genes within and among species. II Human activities are the primary drivers of biodiversity loss, causing habitat destruction, climate change, pollution and the introduction of invasive species. III Conservation efforts and sustainable use of natural resources are essential for maintaining biodiversity. A I and II only C II and III only B I and III only D I, II and III 20. What is the purpose of the taxonomic hierarchy system? A To understand the relationships between different species B To describe a new species C To name a new species D To classify living organisms into different categories based on their characteristics 21. What is the next step in classifying animals after determining their physical characteristics? A Giving the animal a scientific name B Studying the animal’s habitat C Determining the animal’s behaviour D Grouping animals with similar characteristics into a class 22. What type of organism is a fungus? A Prokaryotic B Eukaryotic C Autotrophic D Abiotic 23. Which type of microorganism has a nucleus as part of its cell structure? I Bacteria II Protists III Fungi A I and II only B I and III only C II and III only D I, II and III 24. What is the main difference between mammals and reptiles? A Mammals lay eggs and reptiles give birth to live young. B Reptiles lay eggs and mammals give birth to live young. C Reptiles are warm-blooded and mammals are cold-blooded. D Mammals have dry, scaly skin and reptiles have hair, fur or skin. 25. The figure shows two groups of organisms which live in a garden. Millipede Centipede Earthworm Leech P Q What are groups P and Q? P Q A Molluscs Annelids B Annelids Arthropods C Arthropods Annelids D Arthropods Nematodes 134
26. How does a dichotomous key work? A By comparing the DNA of an organism to a database of organism species B By analysing the chemical composition of an organism C By asking a series of questions that lead to the correct identification of an organism D By classifying organisms based on their physical characteristics 27. A food chain in an oil palm plantation is shown below. Oil palm fruit → squirrel → snake → eagle What would happen to the oil palm fruits if the population of squirrels increases? A Fewer fruits will be produced. B More fruits will be produced. C More fruits will be damaged. D No fruits will develop. 28. A garden community has the following organisms. Scorpion, rattlesnake, cactus, mice Which of the following food chains is correct in showing their relationships within the community? A Cactus → scorpion → mice → rattlesnake B Cactus → mice → scorpion → rattlesnake C Cactus → mice → rattlesnake → scorpion D Mice → cactus → scorpion → rattlesnake 29. Which of the following organisms are decomposers in a freshwater lake? A Fish C Bacteria B Worms D Plankton 30. The figure shows a food web in a paddy field. Paddy plant Grasshopper Sparrow Snake Owl Rat How many food chains are there in the food web? A Two C Four B Three D Five 31. Which of the following forms the base of a pyramid of numbers? A Primary consumers B Secondary consumers C Producers D Decomposers 32. Why does the pyramid of energy get narrower towards the top? A The organisms at the top are smaller in size. B The organisms at the top are less abundant. C The organisms at the top require less energy. D Energy is lost as heat at each transfer. 33. What is the difference between commensalism and mutualism? A Commensalism benefits both species while mutualism benefits one species. B Commensalism benefits one species while mutualism benefits both species. C Commensalism benefits one species while mutualism harms both species. D Commensalism harms both species while mutualism benefits one species. Assessment 2 135
34. How does the burning of fossil fuels affect the carbon cycle? A It has no effect on the carbon cycle. B It increases the amount of carbon dioxide in the atmosphere. C It decreases the amount of carbon dioxide in the atmosphere. D It increases the amount of oxygen in the atmosphere. 35. What are the effects of acid rain on the environment? A Acid rain can increase the growth of plants and animals. B Acid rain has no effect on the environment. C Acid rain can harm trees, bodies of water and soil. D Acid rain makes the environment cleaner. 36. What is the angle at which the Earth’s axis is tilted? A 23.5° C 40° B 33.5° D 42.5° 37. Which of the following phenomena is caused by the rotation of the Earth on its axis? A The occurrence of the wet season and dry season B The occurrence of winter, spring, autumn and summer C The occurrence of day and night D The occurrence of high tides and low tides 38. What do meteors, comets and asteroids have in common? A They are all made of ice and dust. B They are all made of rocks. C They are all made of gases. D They are all celestial objects in space. 39. The figure shows the Moon revolving around the Earth. Q R P Sunlight S Earth Which of the following is correct about the Moon phases? P Q R S A New moon Third quarter moon Full moon First quarter moon B New moon First quarter moon Full moon Third quarter moon C Full moon Third quarter moon New moon First quarter moon D Full moon First quarter moon New moon Third quarter moon 40. Which of the following describes spring tides correctly? A They occur when the Sun, Earth and Moon are lined up in a row. B The difference between the heights of the high tide and the low tide is the smallest. C They are caused by the flow of water in the seas. D They cause massive storms that bring destruction. 136
Section B [60 marks] Answer all questions. 1. The figure shows an experiment conducted by a student. Wooden rod String Balloon Adhesive tape P Q Balloons P and Q are inflated. A piece of adhesive tape is applied on balloon Q. They are balanced on a wooden rod. Then, balloon Q is pricked with a pin through the adhesive tape. (a) Predict what will be observed after 30 seconds. Balloon Q will be deflated, and the wooden rod will slope down towards balloon P. [2 marks] (b) Based on your prediction in (a), state two physical properties of air. Air has mass and occupies space. Air fills any container it is placed in and takes the shape of the container. [2 marks] (c) State whether air is matter or not. Explain your answer. Air is matter because it has mass and occupies space. [2 marks] 2. The figure shows some water is being heated. (a) Name the process occurring to the water in the beaker. Boiling [1 mark] (b) Which change of state takes place during the process in (a)? Liquid to gas [1 mark] Steam Water Wire gauze Assessment 2 137
(c) Draw the particle arrangement in the change of state of matter involved. [2 marks] (d) What is meant by the ‘specific latent heat of vaporisation of water’? The specific latent heat of vaporisation of water is the amount of heat required to change 1 kg of water from a liquid to a gas state at a constant temperature. [1 mark] (e) If it takes 80 kJ of heat energy to convert 0.5 kg of water to steam, what is the specific latent heat of vaporisation of water? Q = mL L = 80 0.5 = 160 kJ/kg [2 marks] 3. The velocity-time graph shows the motion of an object. Velocity (m s–1) Time (s) 0 2 A B C D E 4 6 8 10 5 10 15 20 (a) Which section of the graph shows that the object is moving with uniform velocity? AB [1 mark] (b) Find the displacement from A to C. Displacement = Area between the line and the x-axis = (2 × 10) + 1 2 × 2 × 5 + (2 × 5) = 35 m [2 marks] (c) Find the acceleration of the object from C to D. Acceleration = 20 – 5 8 – 6 = 7.5 m/s2 [2 marks] 138
(d) Find the deceleration of the object from D to E. Acceleration = 0 – 20 10 – 8 = –10 m/s2 Deceleration = 10 m/s2 [2 marks] 4. The figure shows passengers in a moving bus.s (a) Predict what happens when the bus stops suddenly. The passengers will jerk forward. [1 mark] (b) Explain your prediction in (a). This phenomenon is caused by inertia. The inertia of the passengers tends to maintain its original state, which is the state of moving forward. [2 marks] (c) A bus full of passengers is more difficult to stop compared to an empty bus. Relate this situation to inertia. A bus full of passengers has greater mass and therefore greater inertia. [1 mark] (d) Give one example of inertia in daily life. We feel as if our bodies are left behind as the lift starts going down. [1 mark] 5. (a) The figure shows a microorganism. (i) What kingdom does the microorganism belong to? Protist [1 mark] (ii) Is this microorganism unicellular or multicellular? Unicellular [1 mark] (iii) How does it move? It uses its flagella to move. [1 mark] (b) The single-celled microorganisms are found in almost every habitat on Earth. (i) Name the microorganisms shown. Bacteria [1 mark] Assessment 2 139
(ii) Which instrument can be used to observe the microorganisms? Microscope [1 mark] (iii) How do these microorganisms reproduce? They reproduce asexually through binary fission, where a single cell divides into two identical daughter cells. [1 mark] (iv) What is the role of these microorganisms in the ecosystem? As decomposers [1 mark] 6. The figure shows a food chain from a pond ecosystem. Algae Water flea Frog Kingfisher (a) What is a food chain? A food chain is the feeding relationship between organisms in a habitat. [1 mark] (b) Identify the following consumers in the food chain. (i) Secondary consumer: Frog (ii) Tertiary consumer: Kingfisher [2 marks] (c) What happens if all the kingfishers are removed from the habitat? The number of frogs increases [1 mark] (d) (i) Draw a pyramid of energy for this food chain. [2 marks] 140
(ii) Which level of the pyramid of energy has the highest energy? Algae [1 mark] (iii) How is energy lost in the food chain? Lost as heat to the environment [1 mark] 7. The figure shows three planets in the Solar System. Planet P is the third planet from the Sun. Planet Q is the largest planet in the Solar System. Planet R is the farthest known planet in the Solar System. P Q R (a) Name planets P, Q and R. P: Earth Q: Jupiter R: Neptune [3 marks] (b) (i) How long does it take planet P to complete one orbit around the Sun? 365 days [1 mark] (ii) How long does planet P take to complete one rotation on its axis? 24 hours [1 mark] (iii) State the natural satellite of planet P. Moon [1 mark] (c) (i) What is planet Q mainly composed of? It is mainly composed of hydrogen and helium gas. [1 mark] (ii) What is the massive storm on planet Q called? Great Red Spot [1 mark] (d) What makes planet R appear blue? The presence of methane in its atmosphere [1 mark] Assessment 2 141
(e) Which of the three planets given above can support life? Planet P/Earth [1 mark] (f) Which planets are made up of gases? Planet Q and planet R [2 marks] 8. The figure shows the structure of the Sun. Prominence Sunspot Photosphere X: Z: Y: (a) Name the layers labelled X, Y and Z of the Sun’s interior in the figure above. [3 marks] (b) What are the main gases present in the Sun? Hydrogen and helium [2 marks] (c) What are the dark areas that appear on the Sun’s surface called? Sunspots [1 mark] (d) (i) Can solar prominences be seen with the naked eye? No [1 mark] (ii) In which region of the Sun do solar prominences occur? Solar prominences are anchored to the Sun’s surface in the photosphere, and extend outwards into the corona. [1 mark] 142
FOCUS-ON SCIENCE 7 FOCUS-ON SCIENCE WORKBOOK is written to provide students with topical reinforcement exercises and engaging practices to help them consolidate what they have learned. The workbook includes a variety of practice formats, such as matching, fill-in-the-blanks, subjective questions, comparison charts and open-ended questions, among others, which encourage effective reflection and assessment of mastery. Each chapter concludes with objective questions, a concept map and contextual-based higher-order thinking questions. Additional online questions for extra practice are provided through QR codes. The workbook also includes two sets of assessment papers that can be used as tools to evaluate students’ performance in the midterm and final term of the year. The combination of exercises, practices and assessments aims to boost students’ confidence and enhance their mastery of the science concepts learned from the Focus-on Science Textbooks. Focus-on Science comprises: JWSW1723 ISBN 978-981-17295-5-3 WORKBOOK