Structure of Anther and Development of Male Gametophyte

What are the labels A and B indicate in the given picture of a pollen grain?

During pollen germination, intine forms a pollen tube and extrudes out through the germ pore.

Draw the structure of a pollen grain and label the inner layer of the wall of it.

The inner layer of wall surrounding the pollen and spore that protects the reproductive cells is known as _____ (intine/exine).

Exine of pollen helps attachment to _____ (pollinators/stem).

Which of the following feature/s is/are correct about the outermost layer covering the pollen grains?

What is exine? Write two functions of it?

The wall of pollen has an inner layer named intine, and the outer layer is exine.

In the given picture, identify which option indicates outermost coating of a pollen grain:

Liquid nitrogen has a boiling point of -196$°$C that is used as medicine in the removal of precancerous cells, warts, or unwanted skin, and as cryogenics by the researchers. 

Write two important aspects of the creation of the pollen bank.

To store the pollen grains of the desired species as their genetic resources, pollen banks are established. These pollens from the pollen banks are used for _____ (breeding program/pollution control)

Mention two uses of pollen grains that make it economically important.

Pollen grains are used as tablets and syrup because of their _____ (nutritional value/not easily disintegrated).

Since pollen grains are not easily decaying, these are used as natural markers to explain the pollination mechanism, migration routes, and source zones of pollinators like insects.

Pollen grains are used in:

Distally the filament bears ovule.

The stalk of the anther is called the filament.

Give an account on the filament of the anther. 

The middle layer of microsporangial wall is known as nourishing layer.