NEET Practice Questions (MCQs) with Answers & Solutions

Microsporangium is generally surrounded by four wall layers– the epidermis, endothecium, middle layers and the tapetum. The outer three wall layers perform the function of protection and help in dehiscence of anther to release the pollen. The innermost wall layer is the tapetum. It nourishes the developing pollen grains.

(page-21)

Correction for statement C: No enzyme that can degrade sporopollenin is known so far.

(page-23)

The period for which pollen grains remain viable is highly variable and to

some extent depends on the prevailing temperature, humidity and genetic

potentiality of species..

(page-24)

In some cereals such as rice and wheat, pollen grains lose viability within

30 minutes of their release, and in some members of Rosaceae,

Leguminoseae and Solanaceae, they maintain viability for months.

(page-24)

Funicle: The ovule is a small structure attached to the placenta by means

of a stalk called funicle.

Hilum: The body of the ovule fuses with funicle in the region called hilum

Integument:  Each ovule has one or two protective envelopes called

integuments.

Chalaza: . Opposite the micropylar end, is the chalaza, representing the

basal part of the ovule.

Nucellus: Enclosed within the integuments is a mass of cells called the

nucellus.

(page-25)

1. Enclosed within the integuments is a mass of cells called the nucellus. Cells of the nucellus have abundant reserve food materials.
2. Megaspore mother cells are formed after formation of nucellus cells.
3. The process of formation of megaspores from the megaspore mother cell is called megasporogenesis.
4. One of the megaspores is functional while the other three degenerate. Only the functional megaspore develops into the female gametophyte (embryo sac). This method of embryo sac formation from a single megaspore is termed monosporic development.
(page-25, 26)

Transfer of pollen grains from the anther to the stigma of another flower of the same plant. Although geitonogamy is functionally cross-pollination involving a pollinating agent, genetically it is similar to autogamy since the pollen grains come from the same plant.

(page-28)

The above mentioned points explains autogamy.

Allogamy: It is the deposition of pollen grains from the anther of one flower to the stigma of another flower, either in same plant or different plant of the same species.

Xenogamy: Transfer of pollen grains from anther to the stigma of a different plant. This is the only type of pollination which during pollination brings genetically different types of pollen grains to the stigma.

Cross pollination: The transfer of pollen grains from anther of one plant to the stigma of another plant.

(page- 27, 28)

Bees are the dominant biotic pollinating agents because of the secretion of

nectar by flowers, which is collected by them as floral reward to make

honey.

Some flowers are specially adapted for particular species of animals like

daisy and aster attracts bees.

Nectar, pollen grains and shelter for egg laying (the moth deposits its

eggs in the locule of the ovary and the flower, in turn, gets pollinated by

the moth) are the usual floral rewards.

(page- 30)

Outcrossing refers to a cross between individuals of same breed of a

species that have no common ancestors upto 4-6 generations. This

increases genetic diversity by broadening the genetic pool. 

This also limits the chances of bad traits (recessive ones) from getting

passed on. Thus offsprings from outcrosses show additional health and

vigor.