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Primary 5 Science Semestral Assessment 2 (End of Year) Paper 1
Free P5 Science SA2 Paper 1, Nemo3 Exam version, with questions, answers, and syllabus-aligned practice for Singapore students.
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Questions
TuitionGoWhere Practice Paper - Science Primary 5
TuitionGoWhere Exam Practice (AI)
Subject: Science
Level: Primary 5
Paper: SA2 (Semestral Assessment 2) - Version 1
Duration: 1 h 45 min
Total Marks: 100
Name: ________________________
Class: Primary 5 _______
Date: _______________
INSTRUCTIONS TO CANDIDATES
- Do not turn over this page until you are told to do so.
- Follow all instructions carefully.
- Answer all questions.
- For Section A, shade your answers on the Optical Answer Sheet (OAS) provided.
- For Section B, write your answers in the spaces provided in this booklet.
- The number of marks is given in brackets [ ] at the end of each question or part question.
- The total marks for this paper is 100.
SECTION A (56 marks)
For each question from 1 to 28, four options are given. One of them is the correct answer. Make your choice (1, 2, 3 or 4) and shade the correct oval on the Optical Answer Sheet (OAS). Each question carries 2 marks.
Question 1
Which of the following statements about cells is correct?
(1) All cells have a cell wall. (2) Animal cells have chloroplasts. (3) The nucleus controls all activities in the cell. (4) Plant cells do not have a cell membrane.
Question 2
The diagram below shows a plant cell.
Generated diagram for Q1.
Which part (A, B, C or D) controls the movement of substances in and out of the cell?
(1) A (2) B (3) C (4) D
Question 3
Which of the following processes does NOT occur in the mitochondria of a cell?
(1) Respiration (2) Energy release (3) Photosynthesis (4) Breakdown of glucose
Question 4
Study the food chain below.
Grass → Grasshopper → Frog → Snake → Eagle
If a disease kills most of the frogs, what will happen to the grasshopper population?
(1) It will increase. (2) It will decrease. (3) It will remain the same. (4) It will increase then decrease.
Question 5
The diagram below shows a food web.
Generated diagram for Q5.
How many food chains are there in this food web?
(1) 3 (2) 4 (3) 5 (4) 6
Question 6
Which of the following is a structural adaptation of a cactus to survive in the desert?
(1) It has deep roots to absorb water. (2) It stores water in its stem. (3) It opens its stomata at night. (4) It sheds its leaves during dry season.
Question 7
The diagram below shows the human digestive system.
Image pending generation: diagram for Q7.
In which part (A, B, C, D or E) does most absorption of digested food take place?
(1) A (2) B (3) C (4) D
Question 8
Which of the following statements about enzymes in digestion is correct?
(1) Amylase digests proteins into amino acids. (2) Pepsin digests starch into simple sugars. (3) Lipase digests fats into fatty acids and glycerol. (4) All enzymes work best at the same temperature.
Question 9
The diagram below shows the human respiratory system.
Generated diagram for Q9.
Where does gaseous exchange take place?
(1) A (2) B (3) C (4) D
Question 10
Which of the following shows the correct path of air during inhalation?
(1) Nose → Trachea → Bronchus → Alveolus (2) Nose → Bronchus → Trachea → Alveolus (3) Nose → Alveolus → Bronchus → Trachea (4) Nose → Trachea → Alveolus → Bronchus
Question 11
The diagram below shows the human circulatory system.
Generated diagram for Q11.
Which chamber (A, B, C or D) pumps oxygen-rich blood to the rest of the body?
(1) A (2) B (3) C (4) D
Question 12
Which blood vessel carries oxygen-rich blood from the lungs to the heart?
(1) Pulmonary artery (2) Pulmonary vein (3) Aorta (4) Vena cava
Question 13
The diagram below shows a flowering plant.
Generated diagram for Q13.
Where does fertilisation take place in a flowering plant?
(1) A (2) B (3) C (4) D
Question 14
Which of the following is the correct order of stages in the sexual reproduction of flowering plants?
(1) Pollination → Fertilisation → Seed dispersal → Germination (2) Fertilisation → Pollination → Germination → Seed dispersal (3) Seed dispersal → Pollination → Fertilisation → Germination (4) Germination → Seed dispersal → Pollination → Fertilisation
Question 15
The diagram below shows a seed.
Image pending generation: diagram for Q15.
What is the function of part B?
(1) Protects the seed (2) Stores food for the embryo (3) Develops into a new plant (4) Absorbs water from the soil
Question 16
Which of the following conditions is NOT necessary for seed germination?
(1) Water (2) Oxygen (3) Suitable temperature (4) Light
Question 17
The diagram below shows the human reproductive system (female).
Generated diagram for Q17.
Where does fertilisation usually take place in humans?
(1) A (2) B (3) C (4) D
Question 18
Which of the following statements about human reproduction is correct?
(1) The ovary produces sperm. (2) The testes produce eggs. (3) Fertilisation occurs when a sperm fuses with an egg. (4) The fertilised egg develops in the ovary.
Question 19
The diagram below shows the water cycle.
Generated diagram for Q19.
Which process (A, B, C or D) represents water vapour changing into water droplets?
(1) A (2) B (3) C (4) D
Question 20
Which of the following factors will increase the rate of evaporation?
(1) Lower temperature (2) Smaller exposed surface area (3) Presence of wind (4) Higher humidity
Question 21
Water exists in three states. Which of the following shows the correct state change for melting?
(1) Solid → Liquid (2) Liquid → Solid (3) Liquid → Gas (4) Gas → Liquid
Question 22
The diagram below shows the plant transport system.
Generated diagram for Q22.
Which tube (A or B) transports water and mineral salts from the roots to the rest of the plant?
(1) A (2) B
Question 23
Which of the following statements about the plant transport system is correct?
(1) Xylem transports food made by the leaves. (2) Phloem transports water and mineral salts. (3) Xylem tubes are made of dead cells. (4) Phloem tubes are made of dead cells.
Question 24
The diagram below shows an electrical circuit.
Generated diagram for Q24.
What will happen to the bulbs when the switch is closed?
(1) Only Bulb 1 will light up. (2) Only Bulb 2 will light up. (3) Both bulbs will light up. (4) Neither bulb will light up.
Question 25
Which of the following circuits will allow the bulb to light up?
(1) A circuit with a gap in the wire. (2) A circuit with a fused bulb. (3) A complete circuit with a working battery and bulb. (4) A circuit with the switch open.
Question 26
The diagram below shows two electrical circuits, X and Y.
Generated diagram for Q26.
Which of the following statements is correct?
(1) In Circuit X, if one bulb fuses, the other bulb will still light up. (2) In Circuit Y, if one bulb fuses, the other bulb will still light up. (3) The bulbs in Circuit X are brighter than those in Circuit Y. (4) Both circuits use the same amount of electricity.
Question 27
Which of the following materials is a good conductor of electricity?
(1) Rubber (2) Plastic (3) Copper (4) Wood
Question 28
The diagram below shows an electromagnet.
Generated diagram for Q28.
Which of the following will NOT increase the strength of the electromagnet?
(1) Increasing the number of coils of wire. (2) Using a thicker iron nail. (3) Increasing the number of batteries. (4) Using a wooden rod instead of an iron nail.
SECTION B (44 marks)
Write your answers in the spaces provided. The number of marks is given in brackets [ ] at the end of each question or part question.
Question 29
The diagram below shows a plant cell and an animal cell.
Generated diagram for Q29.
(a) Identify two structures present in the plant cell but absent in the animal cell. [2]
(b) State the function of the nucleus. [1]
(c) Explain why chloroplasts are found only in plant cells. [2]
Question 30
The diagram below shows a food web in a garden community.
Generated diagram for Q30.
(a) Write down one food chain with four organisms from the food web. [1]
(b) If all the snakes are removed from the community, explain what will happen to the population of frogs. [2]
(c) State the role of decomposers in the food web. [1]
Question 31
The diagram below shows the human digestive system.
Generated diagram for Q31.
(a) In which organ does digestion of starch begin? [1]
(b) Name the enzyme that digests starch. [1]
(c) The small intestine has many finger-like projections called villi. Explain how the villi help in the absorption of digested food. [2]
Question 32
The diagram below shows the human respiratory system.
Generated diagram for Q32.
(a) Name the tiny air sacs where gaseous exchange takes place. [1]
(b) Describe how the diaphragm and ribs move during inhalation. [2]
(c) Explain why the alveoli have a large surface area. [1]
Question 33
The diagram below shows the human heart.
Generated diagram for Q33.
(a) On the diagram, draw arrows to show the path of oxygen-rich blood from the lungs to the rest of the body. [2]
(b) State one difference between arteries and veins. [1]
(c) Explain why the left ventricle has a thicker muscular wall than the right ventricle. [2]
Question 34
The diagram below shows a flower.
Generated diagram for Q34.
(a) Name the male reproductive part of the flower. [1]
(b) Name the female reproductive part of the flower. [1]
(c) Describe the process of pollination. [2]
Question 35
The diagram below shows the stages of germination of a bean seed.
Generated diagram for Q35.
(a) Arrange the stages in the correct order starting from the dry seed. [1]
(b) State three conditions necessary for germination. [2]
(c) The mass of the seed decreases during the early stages of germination. Explain why. [2]
Question 36
The diagram below shows the water cycle.
Generated diagram for Q36.
(a) Name the process where water changes from liquid to gas at the surface of water bodies. [1]
(b) Explain how clouds are formed. [2]
(c) State one difference between evaporation and boiling. [1]
Question 37
The diagram below shows a cross-section of a plant stem.
Generated diagram for Q37.
(a) Name the tube that transports water and mineral salts. [1]
(b) Name the tube that transports food made by the leaves. [1]
(c) A ring of bark (including phloem) is removed from a tree trunk. Explain why the tree will eventually die. [2]
Question 38
The diagram below shows three electrical circuits, A, B and C.
Generated diagram for Q38.
(a) In which circuit(s) will the bulbs be the brightest? [1]
(b) In which circuit(s) will the bulbs be the dimmest? [1]
(c) Explain your answer for (a) and (b). [2]
Question 39
The diagram below shows an experiment to test electrical conductivity of different materials.
Generated experimental_setup for Q39.
(a) Complete the table below by predicting whether the bulb will light up for each material. [3]
| Material | Bulb lights up (Yes/No) |
|---|---|
| Copper wire | |
| Wooden ruler | |
| Plastic ruler | |
| Steel paper clip | |
| Rubber band |
(b) State the property of materials that allows electricity to pass through them. [1]
Question 40
The diagram below shows an electromagnet being used to separate magnetic materials from non-magnetic materials in a recycling plant.
Generated diagram for Q40.
(a) Which materials will be attracted by the electromagnet? [1]
(b) Suggest two ways to increase the strength of the electromagnet so that it can lift heavier objects. [2]
(c) Explain why the electromagnet is useful in a recycling plant. [1]
Question 41
The diagram below shows the life cycle of a mosquito.
Generated diagram for Q41.
(a) The mosquito has a four-stage life cycle. What is this type of life cycle called? [1]
(b) State one difference between the larva and the adult mosquito. [1]
(c) Mosquitoes lay their eggs in stagnant water. Suggest one way to prevent mosquitoes from breeding. [1]
Question 42
The diagram below shows a cell.
Generated diagram for Q42.
(a) Is this a plant cell or an animal cell? Give a reason for your answer. [2]
(b) Part D controls all activities in the cell. Name part D. [1]
(c) Part E contains chlorophyll. State the function of chlorophyll. [1]
END OF PAPER
Answers
TuitionGoWhere Practice Paper - Science Primary 5 (SA2 Version 1) - Answer Key
Subject: Science
Level: Primary 5
Paper: SA2 (Semestral Assessment 2) - Version 1
Total Marks: 100
SECTION A (56 marks)
| Question | Answer | Marks |
|---|---|---|
| 1 | (3) The nucleus controls all activities in the cell. | 2 |
| 2 | (2) B (cell membrane) | 2 |
| 3 | (3) Photosynthesis | 2 |
| 4 | (1) It will increase. | 2 |
| 5 | (3) 5 | 2 |
| 6 | (2) It stores water in its stem. | 2 |
| 7 | (4) D (small intestine) | 2 |
| 8 | (3) Lipase digests fats into fatty acids and glycerol. | 2 |
| 9 | (3) C (alveolus) | 2 |
| 10 | (1) Nose → Trachea → Bronchus → Alveolus | 2 |
| 11 | (4) D (left ventricle) | 2 |
| 12 | (2) Pulmonary vein | 2 |
| 13 | (4) D (ovule) | 2 |
| 14 | (1) Pollination → Fertilisation → Seed dispersal → Germination | 2 |
| 15 | (2) Stores food for the embryo | 2 |
| 16 | (4) Light | 2 |
| 17 | (2) B (fallopian tube) | 2 |
| 18 | (3) Fertilisation occurs when a sperm fuses with an egg. | 2 |
| 19 | (2) B (condensation) | 2 |
| 20 | (3) Presence of wind | 2 |
| 21 | (1) Solid → Liquid | 2 |
| 22 | (1) A (xylem) | 2 |
| 23 | (3) Xylem tubes are made of dead cells. | 2 |
| 24 | (3) Both bulbs will light up. | 2 |
| 25 | (3) A complete circuit with a working battery and bulb. | 2 |
| 26 | (2) In Circuit Y, if one bulb fuses, the other bulb will still light up. | 2 |
| 27 | (3) Copper | 2 |
| 28 | (4) Using a wooden rod instead of an iron nail. | 2 |
SECTION B (44 marks)
Question 29 [5 marks]
(a) Identify two structures present in the plant cell but absent in the animal cell. [2]
Answer: Cell wall and chloroplast (or large vacuole)
Marking: 1 mark for each correct structure (max 2 marks)
Explanation: Plant cells have a rigid cell wall made of cellulose, chloroplasts for photosynthesis, and a large central vacuole. Animal cells lack these structures.
(b) State the function of the nucleus. [1]
Answer: The nucleus controls all activities in the cell / contains genetic material (DNA) that controls cell activities.
Marking: 1 mark
Explanation: The nucleus is the control centre of the cell. It contains chromosomes made of DNA which carry genetic information for cell division and protein synthesis.
(c) Explain why chloroplasts are found only in plant cells. [2]
Answer: Chloroplasts contain chlorophyll which traps light energy for photosynthesis. Plants make their own food through photosynthesis, while animals obtain food by eating other organisms.
Marking: 1 mark for mentioning photosynthesis/food making; 1 mark for contrasting with animals
Explanation: Chloroplasts are the site of photosynthesis where green plants convert light energy into chemical energy (glucose). Animals are heterotrophs and do not perform photosynthesis, so they do not need chloroplasts.
Question 30 [4 marks]
(a) Write down one food chain with four organisms from the food web. [1]
Answer: Grass → Grasshopper → Frog → Snake (or Grass → Caterpillar → Bird → Hawk, etc.)
Marking: 1 mark for a correct 4-organism chain with correct energy flow direction
Explanation: A food chain shows the transfer of energy from producer to consumers. Arrows should point from food to feeder (e.g., Grass → Grasshopper means grasshopper eats grass).
(b) If all the snakes are removed from the community, explain what will happen to the population of frogs. [2]
Answer: The frog population will increase because snakes are predators of frogs. With no snakes to eat them, fewer frogs will be eaten.
Marking: 1 mark for "increase"; 1 mark for correct explanation (snakes are predators of frogs)
Explanation: This tests understanding of predator-prey relationships. Removing a predator reduces predation pressure on its prey, leading to an increase in the prey population (at least initially).
(c) State the role of decomposers in the food web. [1]
Answer: Decomposers break down dead organisms and waste materials, returning nutrients to the environment for plants to use.
Marking: 1 mark
Explanation: Decomposers (bacteria and fungi) are essential for nutrient cycling. They break down complex organic matter into simple inorganic substances that can be reused by producers.
Question 31 [4 marks]
(a) In which organ does digestion of starch begin? [1]
Answer: Mouth
Marking: 1 mark
Explanation: Salivary amylase in saliva begins breaking down starch into maltose in the mouth.
(b) Name the enzyme that digests starch. [1]
Answer: Amylase
Marking: 1 mark
Explanation: Amylase is the enzyme that catalyses the breakdown of starch (a polysaccharide) into simpler sugars like maltose.
(c) The small intestine has many finger-like projections called villi. Explain how the villi help in the absorption of digested food. [2]
Answer: Villi increase the surface area of the small intestine for faster and more efficient absorption of digested food into the bloodstream.
Marking: 1 mark for "increase surface area"; 1 mark for "faster/more efficient absorption"
Explanation: The small intestine is the main site of absorption. Villi (and microvilli on them) massively increase the surface area, allowing more nutrients to be absorbed per unit time. Each villus contains blood capillaries and a lacteal for transport of absorbed nutrients.
Question 32 [4 marks]
(a) Name the tiny air sacs where gaseous exchange takes place. [1]
Answer: Alveoli (or alveolus)
Marking: 1 mark
Explanation: Alveoli are tiny air sacs at the end of bronchioles where oxygen diffuses into blood and carbon dioxide diffuses out.
(b) Describe how the diaphragm and ribs move during inhalation. [2]
Answer: During inhalation, the diaphragm contracts and moves downwards (flattens), and the ribs move upwards and outwards. This increases the volume of the chest cavity, decreasing air pressure so air rushes in.
Marking: 1 mark for diaphragm movement; 1 mark for rib movement
Explanation: Inhalation is an active process. Diaphragm contraction increases vertical volume; rib movement (by intercostal muscles) increases lateral volume. The pressure drop draws air in.
(c) Explain why the alveoli have a large surface area. [1]
Answer: To allow faster and more efficient gaseous exchange (diffusion of oxygen and carbon dioxide) between the air in the alveoli and the blood in the capillaries.
Marking: 1 mark
Explanation: Large surface area increases the rate of diffusion (Fick's law). Millions of alveoli provide a huge surface area (~70 m² in adults) for rapid gas exchange.
Question 33 [5 marks]
(a) On the diagram, draw arrows to show the path of oxygen-rich blood from the lungs to the rest of the body. [2]
Answer: Arrows should show: Pulmonary vein → Left atrium → Left ventricle → Aorta → Body
Marking: 1 mark for correct path through heart chambers; 1 mark for correct vessels (pulmonary vein and aorta)
Explanation: Oxygen-rich blood from lungs enters left atrium via pulmonary veins, passes to left ventricle, then pumped through aorta to the body.
(b) State one difference between arteries and veins. [1]
Answer: Arteries have thicker muscular walls than veins / Arteries carry blood away from the heart while veins carry blood towards the heart / Arteries carry oxygen-rich blood (except pulmonary artery) while veins carry oxygen-poor blood (except pulmonary vein) / Veins have valves, arteries do not.
Marking: 1 mark for any correct difference
Explanation: Key structural difference: arteries have thick elastic muscular walls to withstand high pressure; veins have thinner walls and valves to prevent backflow at low pressure.
(c) Explain why the left ventricle has a thicker muscular wall than the right ventricle. [2]
Answer: The left ventricle pumps blood to the whole body (systemic circulation) which requires higher pressure, while the right ventricle pumps blood only to the lungs (pulmonary circulation) which requires lower pressure.
Marking: 1 mark for "pumps to whole body/longer distance"; 1 mark for "needs higher pressure/stronger force"
Explanation: Systemic circulation has much higher resistance than pulmonary circulation. The left ventricle must generate enough pressure to push blood through the entire body, requiring a much thicker muscular wall.
Question 34 [4 marks]
(a) Name the male reproductive part of the flower. [1]
Answer: Stamen (anther and filament)
Marking: 1 mark
Explanation: The stamen consists of the anther (produces pollen grains containing male gametes) and filament (supports the anther).
(b) Name the female reproductive part of the flower. [1]
Answer: Pistil (stigma, style, ovary, ovule) / Carpel
Marking: 1 mark
Explanation: The pistil (or carpel) consists of stigma (receives pollen), style (connects stigma to ovary), ovary (contains ovules), and ovules (contain female gametes/egg cells).
(c) Describe the process of pollination. [2]
Answer: Pollination is the transfer of pollen grains from the anther (male part) to the stigma (female part) of a flower. It can occur by wind, insects, or other agents.
Marking: 1 mark for "transfer of pollen from anther to stigma"; 1 mark for mentioning agent (wind/insect) or self/cross-pollination
Explanation: Pollination brings male gametes (in pollen) to the female reproductive organ. Self-pollination: within same flower/plant. Cross-pollination: between different plants (promotes genetic variation).
Question 35 [5 marks]
(a) Arrange the stages in the correct order starting from the dry seed. [1]
Answer: Stage 1 (Dry seed) → Stage 2 (Root emerges) → Stage 3 (Shoot emerges) → Stage 4 (Seedling with leaves)
Marking: 1 mark for correct sequence
Explanation: Germination sequence: water absorption → root (radicle) emerges first to anchor and absorb water → shoot (plumule) emerges →
<stage3_exam_answers_md>
TuitionGoWhere Practice Paper - Science Primary 5 (Answer Key)
TuitionGoWhere Exam Practice (AI)
Subject: Science
Level: Primary 5
Paper: SA2 (Semestral Assessment 2) - Version 1
SECTION A (56 marks)
| Question | Answer | Explanation |
|---|---|---|
| 1 | (3) | The nucleus controls all activities in the cell. Cell walls are only in plant cells; animal cells lack chloroplasts; plant cells have both cell wall and cell membrane. |
| 2 | (2) | B is the cell membrane, which controls the movement of substances in and out of the cell. |
| 3 | (3) | Photosynthesis occurs in chloroplasts, not mitochondria. Mitochondria are the site of respiration, energy release, and glucose breakdown. |
| 4 | (1) | With fewer frogs (predators), the grasshopper population will increase due to reduced predation. |
| 5 | (4) | Food chains: Plant→Rabbit→Fox; Plant→Rabbit→Snake; Plant→Rabbit→Owl; Plant→Mouse→Fox; Plant→Mouse→Snake; Plant→Mouse→Owl = 6 chains. |
| 6 | (2) | Storing water in its stem is a structural adaptation. Deep roots (1) and opening stomata at night (3) are also adaptations but (2) is the classic structural example. Shedding leaves (4) is behavioural/physiological. |
| 7 | (4) | D is the small intestine, where most absorption of digested food takes place. |
| 8 | (3) | Lipase digests fats into fatty acids and glycerol. Amylase digests starch; pepsin digests proteins; enzymes have different optimal temperatures. |
| 9 | (3) | C is the alveolus, where gaseous exchange takes place. |
| 10 | (1) | Correct path: Nose → Trachea → Bronchus → Alveolus. |
| 11 | (4) | D is the left ventricle, which pumps oxygen-rich blood to the body via the aorta. |
| 12 | (2) | Pulmonary vein carries oxygen-rich blood from lungs to left atrium. Pulmonary artery carries deoxygenated blood to lungs. |
| 13 | (4) | D is the ovule, where fertilisation (fusion of male and female gametes) takes place. |
| 14 | (1) | Correct order: Pollination → Fertilisation → Seed dispersal → Germination. |
| 15 | (2) | B is the cotyledon, which stores food for the developing embryo. |
| 16 | (4) | Light is not necessary for germination (though needed for photosynthesis after germination). Water, oxygen, and suitable temperature are essential. |
| 17 | (2) | B is the fallopian tube, where fertilisation usually occurs in humans. |
| 18 | (3) | Fertilisation occurs when a sperm fuses with an egg. Ovaries produce eggs; testes produce sperm; fertilised egg develops in uterus. |
| 19 | (2) | B is condensation, where water vapour changes into water droplets. |
| 20 | (3) | Presence of wind increases evaporation rate by removing saturated air. Higher temperature, larger surface area, and lower humidity also increase evaporation. |
| 21 | (1) | Melting is the change from solid to liquid. |
| 22 | (1) | A is xylem, which transports water and mineral salts from roots upwards. |
| 23 | (3) | Xylem tubes are made of dead, hollow cells. Phloem transports food; phloem tubes are living cells. |
| 24 | (3) | In a series circuit, closing the switch completes the circuit, so both bulbs will light up. |
| 25 | (3) | A complete circuit with working components allows current to flow and the bulb to light up. |
| 26 | (2) | In a parallel circuit (Y), if one bulb fuses, the other still lights up. In series (X), both go out. Bulbs in parallel are brighter. Parallel circuits use more electricity. |
| 27 | (3) | Copper is a good conductor of electricity. Rubber, plastic, and wood are insulators. |
| 28 | (4) | Using a wooden rod instead of an iron nail will not increase strength (wood is not magnetic). More coils, thicker core, and more batteries all increase strength. |
SECTION B (44 marks)
Question 29
(a) Cell wall and chloroplasts (or large central vacuole) [2]
(b) The nucleus controls all activities in the cell / contains genetic material (DNA) that controls cell activities. [1]
(c) Chloroplasts contain chlorophyll for photosynthesis. Plants make their own food through photosynthesis, while animals obtain food by consuming other organisms, so animal cells do not need chloroplasts. [2]
Question 30
(a) Grass → Grasshopper → Frog → Snake (or Grass → Caterpillar → Bird → Hawk, etc.) [1]
(b) The frog population will increase because snakes are predators of frogs. With snakes removed, fewer frogs are eaten. [2]
(c) Decomposers break down dead organisms and waste, returning nutrients to the environment for producers to reuse. [1]
Question 31
(a) Mouth [1]
(b) Amylase (or salivary amylase) [1]
(c) Villi increase the surface area for absorption. They have thin walls (one cell thick) and a rich blood supply, allowing digested food to diffuse quickly into the bloodstream. [2]
Question 32
(a) Alveoli (or air sacs) [1]
(b) During inhalation, the diaphragm contracts and moves downwards (flattens), while the ribs move upwards and outwards. This increases the volume of the chest cavity, decreasing air pressure so air rushes in. [2]
(c) Alveoli have thin walls (one cell thick), are moist, and are surrounded by a dense network of capillaries. This allows rapid diffusion of oxygen into the blood and carbon dioxide out of the blood. [2]
Question 33
(a) Left ventricle [1]
(b) The left ventricle has a thicker muscular wall because it needs to pump blood at high pressure to the entire body, while the right ventricle only pumps blood to the nearby lungs at lower pressure. [2]
(c) Arteries have thick, muscular, elastic walls to withstand high pressure; veins have thinner walls with valves to prevent backflow at low pressure. [2]
Question 34
(a) Stigma [1]
(b) The stigma is sticky to catch pollen grains; the style is a tube that allows the pollen tube to grow down to the ovary. [2]
(c) After fertilisation, the ovule develops into a seed and the ovary develops into a fruit. [2]
Question 35
(a) Water and oxygen [1]
(b) The seed coat protects the embryo from mechanical damage, drying out, and pathogen attack. [1]
(c) The cotyledons store food (starch, proteins, fats) which is broken down by enzymes during germination to provide energy and building materials for the growing embryo until it can photosynthesise. [2]
Question 36
(a) Condensation [1]
(b) Water vapour rises, cools, and condenses into tiny water droplets on dust particles, forming clouds. When droplets combine and become heavy, they fall as rain (precipitation). [2]
(c) The water cycle ensures continuous supply of fresh water, regulates Earth's temperature, and supports all life processes. [1]
Question 37
(a) Xylem [1]
(b) Phloem transports food (sugar) made in the leaves to all parts of the plant for growth and storage. [1]
(c) Xylem: dead hollow cells, thick lignified walls, no cross walls, transports water/minerals upward. Phloem: living cells, sieve plates, companion cells, transports food in both directions. [2]
Question 38
(a) Both bulbs will light up. [1]
(b) In a series circuit, there is only one path for current. If one bulb fuses, the circuit is broken and current cannot flow, so the other bulb goes out. [2]
(c) In a parallel circuit, each bulb has its own path. If one bulb fuses, the other path remains complete, so the other bulb stays lit. [1]
Question 39
(a) Increase the number of coils / Increase the current (more batteries) / Use a soft iron core / Use thicker wire [Any 2] [2]
(b) Steel retains magnetism (hard magnetic material), making it a permanent magnet that cannot be switched off. Iron loses magnetism quickly (soft magnetic material), allowing the electromagnet to be turned on and off. [2]
(c) Electric bell / Relay / Circuit breaker / Magnetic crane / Maglev train [Any 1] [1]
Total: 100 marks
End of Answer Key
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