(a) Fig. 4.1 is a photomicrograph of part of a cross-section of a leaf.
(i) State the name of the structure circled and labelled A on Fig. 4.1.
(ii) Using the information in Fig. 4.1, complete Table 4.1.
(b) State the word equation for photosynthesis.
(c) Root hair cells absorb water.
State one way that root hair cells are adapted for their function.
(d) Describe how tropic responses in plants allow roots to absorb more water from the soil.
▶️ Answer/Explanation
(a)(i) The structure labelled A is the vascular bundle, which contains xylem and phloem for transport.
(a)(ii)
(The table identifies structures like the upper epidermis, palisade mesophyll, and stomata with their functions.)
(b) The word equation for photosynthesis is:
water + carbon dioxide → glucose + oxygen
(This summarizes the light-dependent process in chloroplasts.)
(c) Root hair cells have a large surface area to maximize water and mineral absorption from the soil.
(d) Tropic responses like positive gravitropism (growth toward gravity) and negative phototropism (growth away from light) direct roots deeper into soil, where water is more abundant.
Fig. 3.1 shows a photograph of some leaves on a tree.
(a) State two features of the leaves, visible in Fig. 3.1, that are adaptations for photosynthesis.
(b) Fig. 3.2 is a diagram of part of a cross-section of a leaf.
(i) Explain how the parts of the leaf labelled A, B, C and D in Fig. 3.2 adapt the leaf for gas exchange during photosynthesis.
(ii) State the name of the mineral ion that plants need to make chlorophyll.
(c) Complete the sentences about transport in plants.
Leaves contain ………….. bundles.
The xylem in the bundles provides plants with support and transports water and ………… from the …………. to the leaves.
Phloem in the bundles transports ………….. and amino acids.
▶️ Answer/Explanation
(a) Any two from:
• Large surface area (to maximize light absorption).
• Thin structure (to allow efficient gas exchange and light penetration).
• Presence of chlorophyll (visible as green color, essential for photosynthesis).
(b)(i) Explanations for parts A, B, C, D:
• A (Spongy mesophyll): Loosely packed cells create air spaces for gas diffusion.
• B (Stomata): Openings allow CO2 to enter and O2 to exit.
• C (Guard cells): Regulate stomatal opening to control gas exchange.
• D (Air space): Facilitates movement of gases within the leaf.
(b)(ii) Mineral ion for chlorophyll:
Magnesium (Mg2+), as it is a central component of the chlorophyll molecule.
(c) Transport in plants:
Leaves contain vascular bundles.
The xylem transports water and minerals from the roots to the leaves.
Phloem transports sucrose and amino acids.