1) What changes would take place in meristem cells to get transformed into sclerenchyma cells?
2) How does the branched structure of a neuron help in its function?
3) Mention two features of paremchyma cells that indicate their living nature?
4) How is epidermis modified in a) leaf b) woody stem
c) roots
5) If we cut the root tips of onions, will it grow? Give Reason
Class 9
Answers
1) What changes bring about transformation of meristem to sclerenchyma?
Answer
There are two main changes which result in the conversion or transformation of the meristematic tissues to the sclerenchymatous tissues.
i) There is deposition of ligin on the cell walls of the cells during the process of secondary growth.
ii) The nucleus and the protoplasm are lost.
iii) The sclerenchymatous cells do not have the capability to divide.
2) How does the structure of a neuron help its function?
Answer
While neurons have a lot in common with other types of cells, they're structurally and functionally unique. Specialized projections called axons allow neurons to transmit electrical and chemical signals to other cells. Neurons can also receive these signals via rootlike extensions known as dendrites.
3) Mention two features of paremchyma cells that indicate their living nature?
Answer
Features of parenchyma:
- They form basic packing tissue.
- Cells of this tissue are relatively unspecialised and may be oval, rounded or elongated in shape.
- Their cell walls are thin.
- These cells are living.
- They show large intercellular spaces.
- Cytoplasm is dense with a small nucleuses
4) How is epidermis modified in
a ) leaf
b) woody stem
c) roots
Answer
a ) How is epidermis modified in leaf ?
Answer
Epidermal cells may be modified as glands that secrete protective substances of various types. In leaves, particularly the lower epidermis, specialized epidermal cells (guard cells) form microscopic pores (stomata) and regulate gas exchange between interior and exterior of a leaf.
b) How is epidermis modified in woody stem ?
Answer
In the root epidermis, epidermal hairs termed root hairs are common and are specialized for the absorption of water and mineral nutrients. In plants with secondary growth, the epidermis of roots and stems is usually replaced by a periderm through the action of a cork cambium.
c) How is epidermis modified in roots ?
Answer
In roots, certain epidermal cells are modified into root hairs that increase surface area of the root for absorption of water and minerals and help to anchor the plant firmly in place. ... Epidermal cells may be modified as glands that secrete protective substances of various types.
5) If we cut the root tips of onions, will it grow? Give Reason
Answer
Tip of the onion stop growing in jar 2 because we have cut them , apical meristematic tissues are present on the tip of the plant which helps in the growth of the plant.