Question 1

The digestive system works together with another human system to push food from the mouth to the stomach. Which of the following systems plays that role?
(1) Skeletal system
(2) Muscular system
(3) Circulatory system
(4) Respiratory system

Accepted Answer

(2) Muscular system. The muscular system, specifically the smooth muscles in the esophagus, uses a wave-like motion called peristalsis to push food from the mouth down to the stomach. The other systems listed do not directly perform this action.

Question 2

The diagram below shows three different human systems with different functions. Identify Human Systems A, B and C.

Accepted Answer

(3) Respiratory system | Circulatory system | Digestive system. Human System A 'taken in air' identifies it as the Respiratory System. Human System C 'absorbed by food' identifies it as the Digestive System. Human System B 'sent air and food to All parts of the body' and receives 'absorbed by food' from System C, which identifies it as the Circulatory System, responsible for transporting substances throughout the body. Therefore, A=Respiratory, B=Circulatory, C=Digestive.

Question 3

Study the two plants below. Which of the following statements is definitely true?
(1) Plant H grows slower than Plant G.
(2) Plant H has a stronger stem than Plant G.
(3) Plant G needs more sunlight than Plant H.
(4) Plant G can absorb more water than Plant H.

Accepted Answer

(2) Plant H has a stronger stem than Plant G.. Plant H is depicted with a thicker, more robust stem compared to Plant G which appears to be a climbing plant with a much thinner stem. Thicker stems generally provide more structural support and are indicative of greater strength. Statements about growth rate, sunlight needs, or water absorption cannot be definitively concluded from the visual representation alone.

Question 4

Which of the following does not take place in the mouth?
(1) The tongue rolls food into balls.
(2) The teeth chew and digest food.
(3) The saliva wets the food and helps in swallowing.
(4) The tongue pushes food towards the gullet for swallowing.

Accepted Answer

(2) The teeth chew and digest food.. The teeth chew food (mechanical digestion) in the mouth, and saliva begins the chemical digestion of carbohydrates. However, complete digestion of food does not occur in the mouth; it mainly takes place in the stomach and small intestine. Therefore, 'digest food' as a completed process does not fully take place in the mouth, making option (2) the incorrect statement.

Question 5

The diagram below shows a flowering plant. Which of the following are the functions of the labelled plant parts?

Accepted Answer

(4) A | B | C | A. Based on the diagram:
- Part A is the leaves: responsible for making food (photosynthesis) and exchange of gases.
- Part B is the stem: responsible for holding the plant upright.
- Part C is the roots: responsible for anchoring the plant firmly to the ground.
Matching these functions to the options: (Makes food for the plant) A, (Holds the plant upright) B, (Anchors the plant firmly to the ground) C, (Exchange of gases) A. This matches option (4).

Question 6

Which diagram shows the amount of digested food when food enters the organs in a human digestive system?

Accepted Answer

(1) Amount of Digested Food (mouth: low, gullet: same as mouth, stomach: moderate, small intestine: high, large intestine: same as small intestine). Digestion starts in the mouth (carbohydrates). No significant digestion occurs in the gullet. Protein digestion begins in the stomach. The vast majority of digestion and nutrient absorption occurs in the small intestine. Very little or no further digestion occurs in the large intestine. Chart (1) correctly shows some digestion beginning in the mouth, minimal in the gullet, increasing in the stomach, significantly increasing in the small intestine (where most digestion occurs), and then leveling off in the large intestine.

P4 Science CA1 2025 — Tao Nan

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