Primary 5 Science Systems Quiz

Primary 5 Science Quiz - Systems

Answer Key

Section A: Multiple Choice Questions

1. Answer: (d) Root system [1]
Explanation: The root system is part of a plant, not a system in the human body. The digestive, respiratory, and skeletal systems are all human body systems.

2. Answer: (b) To transport oxygen, nutrients, and waste products around the body [1]
Explanation: The circulatory system, made up of the heart, blood vessels, and blood, is responsible for transporting substances throughout the body.

3. Answer: (c) Xylem [1]
Explanation: Xylem is the vascular tissue in plants that transports water and mineral salts from the roots upwards to the stem and leaves.

4. Answer: (b) A complete circuit with a battery, wires, and a bulb [1]
Explanation: For a bulb to light up, there must be a complete (closed) circuit that includes a power source (battery), conducting path (wires), and a load (bulb).

5. Answer: (c) Alveoli [1]
Explanation: Gas exchange (oxygen in, carbon dioxide out) occurs in the tiny air sacs called alveoli in the lungs, which are surrounded by a network of blood capillaries.

6. Answer: (b) Water and mineral salts [1]
Explanation: Root hairs absorb water and dissolved mineral salts from the soil, which are then transported upward through the xylem.

7. Answer: (b) The bulb does not light up [1]
Explanation: When a circuit is open (broken), electric current cannot flow through the circuit, so the bulb will not light up.

8. Answer: (c) Red blood cells [1]
Explanation: Red blood cells contain haemoglobin, which binds to oxygen in the lungs and carries it to all parts of the body.

9. Answer: (c) Roots → stem → leaves [1]
Explanation: Water is absorbed by the roots, transported up through the stem via the xylem, and finally reaches the leaves where it is used in photosynthesis or lost through transpiration.

10. Answer: (b) To pump blood throughout the body [1]
Explanation: The heart acts as a muscular pump that pushes blood through the blood vessels to all parts of the body.

Section B: Short Answer Questions

11.
(a) The bulb will not light up [1] because the switch is open, which means the circuit is incomplete (open circuit) and electric current cannot flow through. [1]

(b) Close the switch to complete the circuit. [1]
Accept any valid method: e.g., connecting the wire properly, replacing the battery, etc.

12.
(a) Mouth: Food is chewed and mixed with saliva; starch is broken down by salivary amylase. [1]
(b) Stomach: Food is churned and mixed with gastric juices; proteins are broken down by pepsin. [1]
(c) Small intestine: Nutrients are absorbed into the bloodstream; digestion is completed here. [1]
(d) Large intestine: Water is absorbed from undigested food; faeces are formed and stored before removal. [1]
Marking note: Accept any correct function for each organ. Key idea must be present.

13.
(a) The human circulatory system uses a heart to pump blood through blood vessels, while the plant transport system has no pump and relies on processes like transpiration pull and root pressure. [1]
(b) In the human circulatory system, blood flows in one direction through a closed network of vessels, whereas in plants, xylem transports water upwards only and phloem transports food in both directions. [1]
Accept any TWO valid differences. Other acceptable answers: humans have blood, plants have xylem/phloem; human system involves lungs for gas exchange, plant system involves stomata, etc.

14.
(a) A → Trachea (windpipe) [1]; B → Alveoli (air sacs) [1]
(b) The walls of the alveoli are thin and surrounded by many blood vessels to allow efficient gas exchange. [1] The thin walls (one cell thick) provide a short diffusion distance for oxygen to enter the blood and carbon dioxide to leave the blood. [1]
Marking note: Must mention thin walls AND blood vessels/network of capillaries for full marks.

15.
Circuit X (series): The remaining bulb will not light up [1] because when one bulb is removed, the circuit becomes open/incomplete, so no current flows through the circuit. [1]

Circuit Y (parallel): The remaining bulb will continue to light up [1] because each bulb has its own separate path for current to flow, so removing one bulb does not affect the other.
Marking note: Award 1 mark for correct prediction for each circuit and 1 mark for correct explanation of series circuit.

16. The root system absorbs water and mineral salts from the soil, which are essential for the shoot system to carry out photosynthesis and other life processes. [1] Without the root system supplying these necessities, the stem and leaves would not have the raw materials needed to make food and the plant would eventually die. [1]
Marking note: Must link root function (absorption) to shoot system function for full marks.

Section C: Structured / Application Questions

17.
(a) Evaporation [1]

(b) The water cycle is a system because it is made up of interconnected processes (evaporation, condensation, precipitation, and collection) [1] that work together to move water continuously between the Earth's surface and the atmosphere. Each process depends on and affects the others. [1]
Marking note: Key idea = multiple parts working together / interconnected processes.

(c) If the Earth's temperature increased significantly, the rate of evaporation would increase, leading to more water vapour in the atmosphere. [1] This could result in more intense precipitation (heavier rainfall or storms) in some areas, while other areas might experience droughts due to changes in weather patterns. [1]
Marking note: Must mention increased evaporation AND a consequence for full marks.

18.
(a) As the number of bulbs in a series circuit increases, the brightness of each bulb decreases [1] because the same battery voltage is shared among more bulbs, so each bulb receives less energy. [1]
Marking note: Must state the relationship (more bulbs = dimmer) AND explain why (voltage shared / more resistance).

(b) The bulbs would be even dimmer than when there were 3 bulbs [1] because adding a fourth bulb increases the total resistance in the circuit, further reducing the current flowing through each bulb, so each bulb receives even less energy. [1]
Marking note: Must predict "dimmer" AND provide a valid explanation.

19.
(a) Heart valves prevent backflow of blood / ensure blood flows in one direction only through the heart. [1]

(b) The circulatory system is called a "double" circulation because blood passes through the heart twice in one complete circuit around the body [1] — once through the pulmonary circulation (heart → lungs → heart) and once through the systemic circulation (heart → body → heart). [1]
Marking note: Must mention blood passes through heart twice AND name or describe the two circuits.

20.
(a) Xylem [1]

(b) The red streaks appeared in the stem and leaves, showing that the red-coloured water travelled from the roots, through the stem, and up to the leaves through the xylem. [1] This demonstrates that the plant transport system is a connected/continuous system where all parts (roots, stem, leaves) are linked and work together to transport water. [1]
Marking note: Must explain that water moved through the entire connected system.

(c) The stem and leaves would not show red streaks [1] because without roots, there would be no structure to absorb the red-coloured water from the beaker, so the water could not enter the plant's transport system and travel upward. [1]
Marking note: Must predict no red streaks AND explain that roots are needed for absorption.

Total: 40 marks