CIE iGCSE Co-Ordinated Science B6.2 Leaf structure Exam Style Questions Paper 1
▶️ Answer/Explanation
Palisade mesophyll cells are the main site of photosynthesis in a leaf. They are found in the upper part of the leaf and contain many chloroplasts, which are the organelles responsible for converting light energy into chemical energy (glucose) during photosynthesis. Phloem transports sucrose and amino acids, xylem transports water and mineral ions, and spongy mesophyll is involved in gas exchange with fewer chloroplasts. Therefore, palisade mesophyll cells produce the most glucose.
✅ Answer: (A)
✅ Answer: (A)
▶️ Answer/Explanation
In a leaf cross-section, the uppermost single-cell layer at the top of the diagram is the upper epidermis; it lacks chloroplasts and is covered by a waxy cuticle to prevent water loss and protect inner tissues.
Below the upper epidermis lies the palisade mesophyll (tightly packed cells with many chloroplasts), then the spongy mesophyll with air spaces, making it easy to identify P as the top layer.
✅ Answer: (C)
Below the upper epidermis lies the palisade mesophyll (tightly packed cells with many chloroplasts), then the spongy mesophyll with air spaces, making it easy to identify P as the top layer.
✅ Answer: (C)
▶️ Answer/Explanation
Water vapour is lost mainly through the stomata on the lower epidermis by diffusion to the air outside.
Carbon dioxide for photosynthesis also enters through the stomata and diffuses to the palisade and spongy mesophyll cells.
The labelled cells closest to the stomatal pore and air spaces are responsible for the most water loss and carbon dioxide uptake.
✅ Answer: (A)
Carbon dioxide for photosynthesis also enters through the stomata and diffuses to the palisade and spongy mesophyll cells.
The labelled cells closest to the stomatal pore and air spaces are responsible for the most water loss and carbon dioxide uptake.
✅ Answer: (A)
▶️ Answer/Explanation
The spongy mesophyll is the layer of loosely packed, irregularly shaped cells with large air spaces between them.
It lies below the palisade mesophyll and above the lower epidermis in a typical leaf cross-section.
The mark scheme confirms the correct labelled layer is option C.
✅ Answer: (C)
It lies below the palisade mesophyll and above the lower epidermis in a typical leaf cross-section.
The mark scheme confirms the correct labelled layer is option C.
✅ Answer: (C)
Question
One method of preventing food spoilage is to store it at 4 ºC in a refrigerator.
Why does storing food at low temperatures help to prevent food spoilage?
(A) It decreases enzyme activity.
(B) It denatures enzymes.
(C) It increases enzyme production.
(D) It kills cells.
▶️Answer/Explanation
Ans: A