CIE iGCSE Co-Ordinated Science B6.1 Photosynthesis Exam Style Questions Paper 3
Question
Most-appropriate topic codes (Cambridge IGCSE Co-ordinated Sciences 0654):
• Topic B8.1 — Xylem and phloem (Part (a))
• Topic B6.1 — Photosynthesis (Part (b))
• Topic B8.2 — Water uptake (Part (c))
• Topic B8.3 — Transpiration (Part (d))
▶️ Answer/Explanation
(a) Correct line drawn and labelled Y on the phloem tissue in the vascular bundle.
Sucrose is transported in the phloem, which is part of the vascular bundle in the stem. The label line should point to the phloem region.
(b) Plants make carbohydrates using the process of photosynthesis.
This process requires water and carbon dioxide in the presence of light energy and chlorophyll.
Photosynthesis is the process by which plants synthesise carbohydrates from carbon dioxide and water using light energy absorbed by chlorophyll in chloroplasts.
(c) roots → root hair cells → root cortex cells → xylem → leaves → mesophyll cells
Water enters through root hair cells by osmosis, passes through the cortex to the xylem, travels up the stem, and reaches the mesophyll cells in the leaves where it is used for photosynthesis or evaporates.
(d)(i) Transpiration
Transpiration is the loss of water vapour from the leaves of a plant, mainly through stomata.
(d)(ii) Stomata
Stomata are small pores on the leaf surface through which water vapour diffuses out of the leaf during transpiration.
Question
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).
