Question

Which of the following is not part of epidermal tissue system
A. trichomes
B. companion cells
C. guard cells
D. subsidiary cells
E. root hairs

Answer 1

Epidermal tissue system is the outermost layer of the plants. Epidermal tissue is formed by epidermis, epidermal outgrowths and stomata.

Complete Answer:
- Epidermal tissue system is the outermost covering of plant parts. It is the barrier between plant parts and the external environment. Epidermal tissue systems are present around all parts of plants stem, roots, leaves, fruits, etc. Epidermal tissue is formed by the epidermis, epidermal outgrowths and stomata.
- In the case of roots, there is the presence of root hairs. These root hairs arise from the epidermis, that is they are epidermal outgrowths of the root. So, root hairs are part of the epidermal tissue system.
- In the case of the stem, Trichomes are present on the surface of the stem. These are the same as root hairs. These trichomes develop from the epidermis, that is they are epidermal outgrowths of the stem. That’s why they form a part of the epidermal tissue system.
- In the case of leaves, Stomata is part of the epidermal tissue system. These stomata play an important role in the process of transpiration. Stomata is present in the epidermis of the leaf. Stomata are made up of Stomatal pore, Guard cells, and subsidiary cells. As stomata are present in the epidermal tissue system of a leaf, guard cells and subsidiary cells form part of the epidermal tissue system.
- Companion cells are part of vascular tissue phloem. Phloem is not a part of the epidermal tissue system. It is a part of the vascular tissue system.

So, the correct answer is phloem.

Note: Epidermal tissue system helps in the proper normal functioning of plants. The epidermis protects the underlying tissues. Root hair absorbs the water and minerals from the soil. Trichomes help in the protection of plants from herbivorous insects. Stomata is important for transpiration and also exchange of gases occurs through stomata.