Question

Answer question numbers (3.1- 3.4) on the basis of your understanding of the following

paragraph and the related studied concepts.

The leaf is the main photosynthetic organ in a plant. It controls gas exchange in

plants, controls the amount of water loss in plants. Upper epidermis cells contain no

chloroplasts – which is not true for the guard cells. They form layers on the upper and lower

surface of the leaf. Their function is to prevent water from getting out and stopping

unwanted substances/organisms getting in. The palisade mesophyll layer is where most of

the photosynthesis occurs in the leaf. The palisade cells contain a lot of chloroplasts to help

them perform this photosynthesis .Lower epidermis is the bottom layer of the leaf, and is

one cell thick. They may not contain a cuticle within the lower epidermis, there are some

holes found in leaves called stomata. These holes allow gases to diffuse in and out of the

leaves. The stomatas are formed by two highly specialized epidermis cells, called guard

cells. Guard cells are the only epidermis cells that contain chloroplasts.

3.1 Mention two functions of lower epidermis . (1)

3.2 Where are chloroplasts present in the leaf? (1)

3.3 What are the functions of xylem and phloem in leaf? (1)

3.4 List one structural and one functional difference between upper and lower epidermis (1)​

Answer 1

Answer:

Epidermis covers the upper and lower surfaces of the leaf. Usually a single layer of tightly-packed cells, the epidermis mediates exchanges between the plant and its environment, limiting water loss, controlling gas exchange, transmitting sunlight for photosynthesis, and discouraging herbivores.