Question

Give reasons for the following: 1.The growth of the plants occurs only at certain specific regions. 2.It is difficult to pull out the husk of a coconut. 3.Epidermal cells on the aerial parts of a plant secrete waxy, water resistant substance. 4.Intercellular spaces are absent between the cells of sclerenchyma tissue. 5.Braches of tree move and bend freely in high wind speed. 6.Meristematic cells have a prominent nucleus and dense cytoplasm but they lack a vacuole.

Answer 1

1. The growth of plants occurs only in certain regions. This is because the dividing tissue also known as meristematic tissue is located only at these points. growth of plant occurs only in specific places because of the dividing tissue which causes growth is only found in those places.
2. It is difficult to pull out the husk of a coconut tree due to the presence of sclerenchyma tissue. The cells of sclerenchyma tissue are closely packed without intercellular spaces, a middle lamella exists between them.
3. Small pores, called stomata, are present on the leaf, and help in the exchange of gases and water. Epidermal cells on the aerial parts of the plant secrete a waxy, water-resistant layer on their outer surface. ... In desert plants, epidermis has a thick waxy coating of cutin, to check water loss.
4. Intercellular spaces are absent in sclerenchymatous tissues because they have a cementing substance (known as lignin) around their cell membrane which makes them stiff and hard.
5. Branches of a tree move and bend freely in high wind velocity because of the presence of collenchyma that adds the property of flexibility.
6. Meristematic cells are continuously dividing cells so they have a prominent nucleus and dense cytoplasm. But since these cells do not store food material or waste materials, they lack vacuole. Sclerenchyma cells have lignified cell walls which makes them compact and leaves no intercellular spaces.

Answer 2

1. Growth of plants occurs only at certain specific regions due to the presence of meristematic tissues(Tissues that divide to form other tissues.

2. Husk of the coconut is made of schlerenchyma tissue which is made of dead cells. It has No Inter cellular space between them and are thick walled. So, its difficult to pull out husk of a coconut.

3.They secrete waxy which is water resistant substance to avoid transpiration(loss of water).

4. Schlerenchyma tissues are found in bark, stem and coverings of nuts. These tissues provide rigid support to the plants as they dont have ICS. So, due to their support the tree can stand.

5. Branches of tree are made of collenchyma tissues. The collenchymatous tissues are flexible. they can bend without breaking. So when air moves(wind) in high speed, they move in the direction of the air and can bend freely due to presence of collenchyma tissue.

6. Meristematic tissues are actively dividing to form new tissues. As a result, they have prominent nuclei and dense cytoplasm so that division happens smoothly. Since they are actively dividing, there is no need for them to store food. As vacuole stores food, they dont need it.