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CIE iGCSE Co-Ordinated Science B7.2 Digestive system Exam Style Questions Paper 3

CIE iGCSE Co-Ordinated Science Paper 3 - All Chapters

Question

(a) Fig. 1.1 is a diagram of the alimentary canal and associated organs.
(i) Identify the parts labelled A, C and E in Fig. 1.1.
(ii) Egestion occurs through structure D. Complete the sentence to describe egestion.
Egestion is the removal of …………………………………………………… food from the body as ………………….
(iii) State the name of a hormone produced by the part labelled B.
(b)(i) Reducing sugars are absorbed into the blood from the alimentary canal.
Describe the test for reducing sugar and the colour change observed for a positive result.
(ii) Complete the word equation for photosynthesis:
………………………….. + carbon dioxide → ………………………….. + …………………………..
(iii) The carbon dioxide needed for photosynthesis diffuses into the plant through the stomata.
Place ticks (\( \checkmark \)) in two boxes to show the statements that correctly describe diffusion.

Most-appropriate topic codes (Cambridge IGCSE Coordinated Sciences 0654):

• Topic B7.2 — Digestive system (Part (a)(i), (a)(ii), (a)(iii))
• Topic B4.1 — Biological molecules (Part (b)(i))
• Topic B6.1 — Photosynthesis (Part (b)(ii))
• Topic B3.1 — Diffusion (Part (b)(iii))

▶️ Answer/Explanation

(a)(i) A – stomach; C – large intestine; E – gall bladder
The stomach (A) is a muscular organ that churns food and secretes digestive juices. The large intestine (C) is responsible for absorbing water and forming faeces. The gall bladder (E) stores bile produced by the liver.

(a)(ii) Egestion is the removal of undigested food from the body as faeces
Egestion refers to the elimination of waste material that has not been absorbed during digestion. This is different from excretion, which removes metabolic waste products.

(a)(iii) Insulin
The pancreas (B) produces the hormone insulin, which regulates blood glucose concentration by promoting the uptake of glucose into cells and its conversion to glycogen in the liver.

(b)(i) Test: Heat with Benedict’s solution; Starting colour: Blue; Final colour: Red/orange/yellow/green
Benedict’s solution is a blue reagent that changes colour in the presence of reducing sugars. The final colour depends on the concentration, ranging from green (low) through yellow and orange to red (high concentration).

(b)(ii) Water + carbon dioxide → oxygen + glucose
Photosynthesis uses water and carbon dioxide as raw materials. In the presence of light and chlorophyll, these are converted into glucose (a carbohydrate) and oxygen gas is released as a by-product.

(b)(iii) Ticks in boxes: “Diffusion is the net movement of particles” and “Diffusion is the result of random movement of particles”
Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. This occurs because of the random, continuous motion of particles. The other statements describe movement against a concentration gradient (which requires energy) or involve partially permeable membranes (which describes osmosis).

Question

(a) Fig. 2.1 is a diagram of the human digestive system.
(i) Using letters A–G in Fig. 2.1, identify:
the anus 
the liver 
(ii) Using letters A–G in Fig. 2.1, identify an organ where these processes occur:
absorption 
digestion 
(b) Complete the sentences about digestion.
The breakdown of food into smaller pieces is called …………………… digestion.
This increases the surface area of the food.
The food is then broken down from large …………………… molecules to small …………………… molecules.
This is called …………………… digestion and produces molecules that can be absorbed.
(c) Table 2.1 shows the nutrition label from a bag of rice.
(i) Use Table 2.1 to calculate the percentage of protein in the rice.
(ii) Table 2.1 gives four types of nutrients needed for a healthy diet.
State one other type of nutrient needed for a healthy diet.

Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):

• Topic B7.2 — Digestive system (Part (a))
• Topic B7.3 — Digestion (Part (b))
• Topic B7.1 — Diet (Part (c))

▶️ Answer/Explanation

(a)(i) the anus: E ; the liver: G
The anus is the terminal opening of the alimentary canal, labelled E in the diagram. The liver is a large organ located above the stomach, labelled G.

(a)(ii) absorption: D or F ; digestion: A or B or F
Absorption of nutrients occurs mainly in the small intestine (D) and also in the large intestine (F). Digestion begins in the mouth (A), continues in the stomach and small intestine, and also occurs in the large intestine (F) where bacteria digest some material.

(b) physical / mechanical ; insoluble ; soluble ; chemical
Physical/mechanical digestion breaks food into smaller pieces, increasing surface area. Chemical digestion breaks down large insoluble molecules into small soluble molecules that can be absorbed through the intestinal wall into the blood.

(c)(i) Percentage of protein = (8.5 ÷ 235) × 100 = 3.6%
To calculate percentage, divide the mass of protein by the total mass of the rice and multiply by 100.

(c)(ii) Vitamins / minerals / water
A balanced diet requires vitamins, minerals (such as calcium and iron), and water in addition to carbohydrates, fats, proteins and fibre.

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