Practicing Success

Target Exam

CUET

Subject

Biology

Chapter

Sexual Reproduction in Flowering Plants

Question:

Read the passage and answer the following questions:
A typical microsporangium, when observed in a transverse section, has a nearly circular shape. It is typically surrounded by four layers of walls: the epidermis, endothecium, middle layers, and the tapetum. The outer three wall layers serve to protect the microsporangium and aid in the anther's opening to release the pollen. The innermost wall layer, known as the tapetum, provides nourishment to the developing pollen grains. Tapetum cells are characterized by their dense cytoplasm and often contain multiple nuclei. In angiosperms, an anther usually consists of two lobes, each with two theca, making it dithecous. The theca are often separated by a longitudinal groove. The anther itself has a tetragonal shape with four microsporangia situated at its corners, two in each lobe. These microsporangia undergo further development and transform into pollen sacs.

 

What is the process of formation of microspores from a pollen mother cell (PMC) through meiosis is called?

Options:

Megasporangium.

Microsporogenesis.

Megasporogenesis.

Microsporangia.

Correct Answer:

Microsporogenesis.

Explanation:

The correct answer is Option (2) - Microsporogenesis.

The pollen grains represent the male gametophytes. As the anther develops, the cells of the sporogenous tissue undergo meiotic divisions to form microspore tetrads. As each cell of the sporogenous tissue is capable of giving rise to a microspore tetrad. Each one is a potential pollen or microspore mother cell. The process of formation of microspores from a pollen mother cell (PMC) through meiosis is called microsporogenesis. The microspores, as they are formed, are arranged in a cluster of four cells–the microspore tetrad. As the anthers mature and dehydrate, the microspores dissociate from each other and develop into pollen grains. Inside each microsporangium several thousands of microspores or pollen grains are formed that are released with the dehiscence of anther.