Primary 5 Science Semestral Assessment 2 (End of Year) Paper 1

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)

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 →

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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)

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