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Primary 6 PSLE Science Systems Quiz
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Questions
Primary 6 PSLE Science Quiz - Systems
Name: ___________________________
Class: ___________________________
Date: ___________________________
Score: ________ / 40
Duration: 40 minutes
Total Marks: 40
Instructions
- Answer all questions.
- Write your answers in the spaces provided.
- The number of marks for each question is shown in brackets [ ].
- You are advised to spend about 2 minutes per mark.
- This quiz focuses on the topic Systems — the human body's organ systems and plant transport systems.
Section A: Multiple Choice Questions (10 marks)
Questions 1–10: Choose the most accurate answer. Each question carries 1 mark.
1. Which organ system is responsible for transporting oxygen and nutrients to all parts of the body?
(A) Digestive system (B) Circulatory system (C) Respiratory system (D) Nervous system
Answer: ___________
2. What is the main function of the root system in a plant?
(A) To make food through photosynthesis (B) To absorb water and mineral salts from the soil (C) To transport food to the leaves (D) To release oxygen into the air
Answer: ___________
3. Which component of blood carries oxygen from the lungs to the rest of the body?
(A) White blood cells (B) Platelets (C) Red blood cells (D) Plasma
Answer: ___________
4. In which part of the plant does photosynthesis mainly take place?
(A) Roots (B) Stem (C) Leaves (D) Flowers
Answer: ___________
5. Which blood vessel carries oxygen-rich blood away from the heart to the body?
(A) Vein (B) Capillary (C) Artery (D) Ventricle
Answer: ___________
6. What is the function of xylem tissue in a plant?
(A) To transport food (sugar) from the leaves to other parts (B) To transport water and mineral salts from the roots to the leaves (C) To absorb sunlight for photosynthesis (D) To protect the plant from insects
Answer: ___________
7. Which organ pumps blood throughout the circulatory system?
(A) Lungs (B) Brain (C) Heart (D) Liver
Answer: ___________
8. What is the function of phloem tissue in a plant?
(A) To transport water from the roots (B) To transport food made in the leaves to other parts of the plant (C) To absorb carbon dioxide from the air (D) To anchor the plant in the soil
Answer: ___________
9. Which of the following is NOT a function of the skeletal system?
(A) Protecting internal organs (B) Supporting the body (C) Transporting oxygen (D) Helping the body move
Answer: ___________
10. When we breathe in, which system is directly involved in taking in oxygen?
(A) Digestive system (B) Circulatory system (C) Respiratory system (D) Muscular system
Answer: ___________
Section B: Short Answer Questions (20 marks)
Questions 11–16: Write your answers in the spaces provided.
11. [2 marks]
The diagram below shows a simplified human digestive system. Name two organs where digestion of food takes place, and state what each organ digests.
(a) Organ 1: _______________ Digests: _______________
(b) Organ 2: _______________ Digests: _______________
12. [3 marks]
The table below shows three types of blood vessels. Complete the table by filling in the missing information.
| Feature | Artery | Vein | Capillary |
|---|---|---|---|
| Direction of blood flow (relative to heart) | Away from the heart | _______________ | — |
| Wall thickness | Thick, muscular | Thin | _______________ |
| Presence of valves | No | _______________ | No |
13. [3 marks]
Study the diagram of a plant below.
(a) Label the arrow that shows the direction of water movement through the plant. [1]
(b) Through which tissue does water travel from the roots to the leaves? [1]
(c) Explain why the leaves of a plant need a constant supply of water. [1]
14. [4 marks]
The human circulatory system is a closed system.
(a) What does "closed circulatory system" mean? [1]
(b) State two differences between the pulmonary circuit and the systemic circuit in the human body. [2]
(c) Why is it important that blood flows in one direction through the heart? [1]
15. [4 marks]
A student set up an experiment with two identical potted plants. Plant A had all its leaves covered with aluminium foil, while Plant B was left uncovered. Both plants were placed in sunlight for 6 hours.
(a) What is the independent variable in this experiment? [1]
(b) After 6 hours, a leaf from each plant was tested for the presence of starch. Predict the results for Plant A and Plant B. [2]
(c) Explain your prediction for Plant A. [1]
16. [4 marks]
The diagram shows the human respiratory system.
(a) Name the structures labelled X (windpipe) and Y (air sacs). [2]
(b) State two features of structure Y that make it efficient for gas exchange. [2]
Section C: Structured / Longer Response Questions (10 marks)
Questions 17–20: Answer in complete sentences. Show your reasoning clearly.
17. [3 marks]
Explain how the digestive system and the circulatory system work together to provide energy to the body. Your answer should include what happens to food after it is digested and how the nutrients reach the body cells.
18. [3 marks]
A plant was placed in a beaker of red-coloured water. After 24 hours, the stem was cut and examined.
(a) Describe what would be observed when the stem is cut. [1]
(b) Explain why this observation occurs. [2]
19. [2 marks]
The heart has four chambers: two atria (upper chambers) and two ventricles (lower chambers). Explain why the walls of the ventricles are thicker than the walls of the atria.
20. [2 marks]
A student says: "The root system and the shoot system of a plant are independent of each other — they do not need each other to function." Do you agree? Explain your answer with two reasons.
End of Quiz
Answers
Primary 6 PSLE Science Quiz — Systems: Answer Key
Topic: Systems (Human Body Systems & Plant Transport Systems) Total Marks: 40
Section A: Multiple Choice Questions (10 marks)
1. (B) Circulatory system [1]
- The circulatory system, consisting of the heart, blood vessels, and blood, transports oxygen, nutrients, hormones, and waste products throughout the body.
- Common mistake: Students may confuse this with the respiratory system, which only exchanges gases.
2. (B) To absorb water and mineral salts from the soil [1]
- Roots anchor the plant and absorb water and dissolved mineral salts from the soil.
- Common mistake: Choosing (A) — photosynthesis occurs in the leaves, not the roots.
3. (C) Red blood cells [1]
- Red blood cells contain haemoglobin, which binds to oxygen in the lungs and carries it to body tissues.
- Common mistake: Students may select plasma, which carries dissolved substances but not oxygen directly.
4. (C) Leaves [1]
- Leaves contain chloroplasts with chlorophyll, which absorb sunlight for photosynthesis.
- Common mistake: Some students may choose stem, but while some green stems can photosynthesise, leaves are the main site.
5. (C) Artery [1]
- Arteries carry blood away from the heart. The pulmonary artery is the exception (carries deoxygenated blood), but generally arteries carry oxygen-rich blood.
- Common mistake: Students often confuse arteries and veins.
6. (B) To transport water and mineral salts from the roots to the leaves [1]
- Xylem vessels are hollow, dead cells that form continuous tubes for upward water transport.
- Common mistake: Confusing xylem with phloem (which transports food).
7. (C) Heart [1]
- The heart is a muscular pump that contracts to push blood through the circulatory system.
- Common mistake: Students may choose lungs, thinking of gas exchange rather than blood pumping.
8. (B) To transport food made in the leaves to other parts of the plant [1]
- Phloem tissue transports sugars (food) produced during photosynthesis from the leaves to other plant parts (translocation).
- Common mistake: Confusing phloem with xylem.
9. (C) Transporting oxygen [1]
- Transporting oxygen is the function of the circulatory system (red blood cells), not the skeletal system.
- Marking note: Students should be able to distinguish between organ systems and their functions.
10. (C) Respiratory system [1]
- The respiratory system (nose, trachea, lungs, diaphragm) is responsible for gas exchange — taking in oxygen and removing carbon dioxide.
- Common mistake: Students may choose circulatory system, which transports gases but does not directly take in oxygen from the air.
Section B: Short Answer Questions (20 marks)
11. [2 marks]
(a) Organ 1: Stomach Digests: Proteins (using gastric juice / pepsin / hydrochloric acid) [1]
(b) Organ 2: Small intestine Digests: Carbohydrates, proteins, and fats (using enzymes from pancreas and intestinal wall) [1]
Acceptable alternatives:
- Organ 1: Mouth — digests starch (using salivary amylase)
- Organ 2: Large intestine — absorbs water (not digestion, so only accept if student explains water absorption)
Marking note:
- Award 1 mark for each correct organ-function pair.
- The stomach and small intestine are the most commonly expected answers.
12. [3 marks]
| Feature | Artery | Vein | Capillary |
|---|---|---|---|
| Direction of blood flow (relative to heart) | Away from the heart | Towards the heart [1] | — |
| Wall thickness | Thick, muscular | Thin | Very thin (one cell thick) [1] |
| Presence of valves | No | Yes [1] | No |
Marking note:
- "One cell thick" or "thin wall" are both acceptable for capillaries.
- Valves in veins prevent backflow of blood.
13. [3 marks]
(a) The arrow should point upward (from roots → stem → leaves). [1]
(b) Water travels through xylem tissue. [1]
(c) Leaves need water for photosynthesis (water is a raw material needed to make food/glucose). [1]
Acceptable alternatives for (c):
- Water is needed to keep the leaf cells turgid / maintain the shape of the leaf.
- Water is needed for transpiration (cooling the plant).
Marking note:
- Award the mark for any valid reason linked to photosynthesis or plant function.
14. [4 marks]
(a) A closed circulatory system means that blood flows within blood vessels (it does not leave the vessels and bathe the organs directly). [1]
Acceptable: "Blood is contained within a network of blood vessels at all times."
(b) Two differences between the pulmonary circuit and systemic circuit: [2 — 1 mark each]
| Feature | Pulmonary Circuit | Systemic Circuit |
|---|---|---|
| Pathway | Heart → Lungs → Heart | Heart → Body → Heart |
| Blood type carried by arteries | Deoxygenated blood | Oxygenated blood |
| Distance | Shorter | Longer |
| Pressure | Lower | Higher |
Any two valid differences earn 2 marks.
(c) Blood must flow in one direction to ensure efficient delivery of oxygen and nutrients to the body and removal of waste products (carbon dioxide). If blood flowed backwards, the body would not receive enough oxygen. [1]
Acceptable: "To prevent mixing of oxygen-rich and oxygen-poor blood" or "Valves in the heart prevent backflow, ensuring proper circulation."
15. [4 marks]
(a) Independent variable: Whether the leaves are covered or uncovered (presence/absence of light on the leaves). [1]
(b) Prediction: [2 — 1 mark each]
- Plant A (covered): The leaf will test negative for starch (no blue-black colour with iodine / remains brown).
- Plant B (uncovered): The leaf will test positive for starch (turns blue-black with iodine).
(c) Explanation for Plant A: [1]
- The aluminium foil blocked light from reaching the leaves. Without light, photosynthesis could not occur, so no starch was produced. Since starch is a product of photosynthesis, the absence of light means no starch is formed.
Marking note:
- Students must link the absence of light to the inability to carry out photosynthesis, and therefore no starch production.
16. [4 marks]
(a) [2 — 1 mark each]
- X = Trachea (windpipe)
- Y = Alveoli (air sacs)
(b) Two features of alveoli for efficient gas exchange: [2 — 1 mark each]
- Thin walls (one cell thick) — allows gases to diffuse quickly across the membrane.
- Large surface area (millions of alveoli) — provides a large area for gas exchange.
- Surrounded by a network of blood capillaries — maintains a concentration gradient for diffusion.
- Moist surface — gases dissolve in the moisture before diffusing.
Any two valid features earn 2 marks.
Section C: Structured / Longer Response Questions (10 marks)
17. [3 marks]
Expected answer (any 3 valid points):
-
The digestive system breaks down large food molecules (carbohydrates, proteins, fats) into smaller, soluble molecules (glucose, amino acids, fatty acids) through mechanical and chemical digestion. [1]
-
These small, soluble nutrients are absorbed through the walls of the small intestine into the blood capillaries. [1]
-
The circulatory system (blood) then transports these nutrients to all parts of the body where they are needed for energy, growth, and repair. [1]
Marking note:
- Award 1 mark for each clear, correct point linking digestion → absorption → transport.
- The answer must show a clear connection between the two systems, not just describe each system separately.
- Award a maximum of 2 marks if the answer describes the systems independently without linking them.
18. [3 marks]
(a) When the stem is cut, red-coloured dots or lines would be observed in the cross-section of the stem. [1]
(b) Explanation: [2]
- The red-coloured water was absorbed by the roots and transported upward through the xylem tissue in the stem. [1]
- The xylem vessels are arranged in a ring (or specific pattern) in the stem, which is why the red colour appears as dots or lines in the cross-section. [1]
Marking note:
- Part (a) requires a description of the observation (red dots/lines/pattern in the stem).
- Part (b) must mention xylem and the direction of transport (upward from roots).
19. [2 marks]
Expected answer:
- The ventricles have thicker muscular walls than the atria because they need to pump blood with greater force/pressure. [1]
- The left ventricle pumps blood to the entire body (systemic circuit), which requires much more force than the atria, which only push blood a short distance into the ventricles. [1]
Acceptable: "The ventricles need to generate enough pressure to push blood through the entire circulatory system, while the atria only push blood down into the ventricles."
Marking note:
- Award 2 marks for a complete explanation linking wall thickness to the pumping function.
- Award 1 mark for only stating that ventricles pump blood harder without explaining why.
20. [2 marks]
Expected answer: Disagree. [1 mark for correct stance with reasoning]
Two reasons why the root system and shoot system depend on each other:
-
The root system absorbs water and mineral salts, which are transported to the shoot system (leaves) and are needed for photosynthesis. Without water from the roots, the leaves cannot make food. [1]
-
The shoot system (leaves) makes food through photosynthesis, which is transported to the roots for energy and growth. Without food from the leaves, the roots cannot function or grow. [1]
Marking note:
- Award 1 mark for disagreeing and providing one valid reason.
- Award 2 marks for disagreeing and providing two valid reasons.
- If the student agrees but gives a partially correct explanation, award a maximum of 1 mark for any valid scientific point.
End of Answer Key