Because of which substance are pollen grains well preserved as fossils?

Complete the following flow chart:
Pollen Mother cell $\to$ Pollen tetrad $\to$ Pollen grain $\to$ Vegetative cell
Pollen Mother cell $\to$ Pollen tetrad $\to$ Pollen grain $\to$ ..........

Choose the correct option with respect to the function of the germ pore.

Which of the following is surrounded by a carbohydrate-rich wall?

The innermost wall layer of anther:

Identify the incorrect statement regarding the sporogenous tissue.