Sexual Reproduction in Flowering Plants

These flashcards cover key concepts and facts related to the sexual reproduction in flowering plants, focusing on pollen grains and their structures.

What is the size range of pollen grains in micrometers?

Pollen grains measure about 25-50 micrometers in diameter.

What is the outer layer of a pollen grain called?

The outer layer is called the exine.

What is sporopollenin?

Sporopollenin is a resistant organic material that makes up the exine of pollen grains.

What are germ pores?

Germ pores are prominent apertures on the exine where sporopollenin is absent.

Why are pollen grains well-preserved as fossils?

Pollen grains are well-preserved due to the presence of sporopollenin.

What are the two types of cells contained in a mature pollen grain?

A mature pollen grain contains a vegetative cell and a generative cell.

What distinguishes the vegetative cell from the generative cell in pollen grains?

The vegetative cell is bigger, has abundant food reserves and a large nucleus, while the generative cell is smaller and spindle-shaped.

What percentage of angiosperms shed pollen grains at the 2-celled stage?

Over 60 percent of angiosperms shed pollen grains at the 2-celled stage.

What is the result of mitotic division of the generative cell in some pollen grains?

It gives rise to two male gametes before pollen grains are shed.

What is a common allergic reaction associated with pollen grains?

Pollen grains can cause severe allergies and bronchial afflictions, including chronic respiratory disorders like asthma and bronchitis.

What plant is known for causing pollen allergy in India?

Parthenium, or carrot grass, which is common due to its introduction as a contaminant with imported wheat.