Question

Formation of Which of the following is connected with Ubisch bodies?
A) Sporopollenin
B) Intine and pollenkitt
C) Exine
D) Pollenkitt and pollinia

Answer 1

Hint:Male reproductive organ, androecium is composed of individual units called stamens. Stamens have two parts, anther and filament. The male gametophyte is represented by the pollen grains, which is produced in anther.

Complete answer:
Pollen grains have spherical shape and size is about 25-50 micrometers in diameter. It contains a double layered wall. Outer layer Is known as exine, which is hard in nature and is made up of the most resistant organic material called Sporopollenin. Therefore, pollen grains are considered as the well-preserved fossil. Sporopollenin can resist high temperatures and strong alkali and acids. Germ pore is the region in exine, where sporopollenin is absent.

Microsporangium contains four layers in its wall, they are, epidermis, endothecium, middle layers and tapetum. Epidermis, endothecium and middle layers help in protection and dehiscence of anther for releasing pollen grains. Tapetum is the innermost layer, which nourishes the developing pollen grains. When the anther is in its growing stage, the cells of tapetum contain many spherical pro-ubisch bodies. Meiosis in pollen mother cells increases the number of pro-ubisch bodies. Ubisch bodies are formed when the pro-ubisch bodies are coated with sporopollenin. Ubisch bodies are also known as orbicules, which are involved in the formation of exine.

Intine is the inner wall of pollen grain. It is a thin, continuous layer and made up of pectin and cellulose. Plasmamembran surrounds the cytoplasm of pollen grains. Mature pollen grains have two cells, generative cell and vegetative cell. Generative cell is small and floats in the cytoplasm of vegetative cell. Generative cell is spindle shaped and has a dense cytoplasm and nucleus. Vegetative cell is bigger in size and contains abundant food reserves and irregular shaped nucleus.
Pollenkitt is a sticky covering seen in the surface of pollen grains. It is also known as pollen coat. It is common in plants that are pollinated by insects.

Pollinia are the mass of pollen grains formed from only one anther and can be transferred as a single unit during pollination.

So, here the correct answer is (C) Exine.

                                            Figure: Pollen grain

Note: Pollen grains of many species can cause allergies and bronchial problems in some peoples, which often leads to respiratory disorders such as asthma, bronchitis. Carrot grass can cause pollen allergy. The period in which pollen grain remains viable is highly variable and depends on temperature and humidity.