Question

Assertion: Endothecium layer of anther wall plays an important role in dehiscence of anther.

Reason: The presence of fibrous bands and differential expansion of inner and outer tangential walls of endothecial cells cause dehiscence of anther.

• A. Both assertion and reason are true and reason is the correct
  explanation of assertion
• B. Both assertion and reason are true but reason is not the correct explanation of assertion
• C. Assertion is true but reason is false
• D. Both assertion and reason are false

Answer 1

The correct option is A Both assertion and reason are true and reason is the correct

explanation of assertion
Microsporangium is generally surrounded by four wall layers – the epidermis, endothecium, middle layers and the tapetum.

The outer three wall layers (epidermis, endothecium, middle layers) perform the function of protection and help in dehiscence of anther to release the pollen.
The cells of endothecium are radially elongated and develop fibrous thickenings which arise from inner tangential walls, at maturity. These fibrous thickenings are made up of alpha cellulose and traces of lignin. The outer tangential walls remain thin.
Endothecium has hygroscopic nature. The inner tangential walls are unable to stretch as the anther matures, because of fibrous thickenings but the outer walls are thin and they can expand as the anther matures. Due to this uneven and differential expansion of outer and inner tangential walls, and the hygroscopic nature of endothelial cells, the endothecium helps in anther dehiscence at maturity.