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1.

A particular species of plant produces light, non-sticky pollen in large numbers and its stigmas are long and feathery. These modifications facilitate pollination byA. insectsB. waterC. windD. animals

Answer» Correct Answer - C
plants use two abiotic (wind and water) and one biotic (animals ) agent to achieve pollination. Majority of plants use biotic agents for pollination.
Pollination by wind is more common amongst abiotic pollination. Wind pollination requires the light and non-sticky pollen grains so that, they can be transported in wind currents.
They often possess well-exposed stamens (so that the pollens are easily dispersed into wind currents) and large often-feathery stigma to easily trap air-borne pollen grains. Wind pollination is common in grasses.
(i) Pollination by water (hydrophily) is quite rare in flowering plants but accuss in aquatic plants.
(ii) Zoophihy is pollination through the agency of animals.
(iii) Entomophily is the most common type of zoophily through the agency of insects.
Discussion
2.

The phenomenon wherein, the ovary develops into a fruit without fertilisation is calledA. parthenocarpyB. apomixisC. asexual reproductionD. sexual reproduction

Answer» Correct Answer - A
Parthenocarpy (GK. Parthenos-virgin, karpos-fruit) is the formation of seed less fruits without fertilisation . The truits developed from unfertilised ovary are called parthenocarpic fruits . Other options are incorrect because
(i) In asexual reproduction , a single individual (parent) is capable of producing off spring.
(ii) For apomixis and sexual reproduction (Also, refer to Q. 18)
Discussion
3.

From the statements given below, choose the option that are true for a typical femal gametophyte of a flowering plant. (i) It is 8-nucleate and 7-celled at maturity. (ii) It is free-nuclear during the development. (iii) It is situated inside the integument but outside the nucellus. (iv) It has an egg apparatus situated at the chalazal end.A. (i) and (iv)B. (ii) and (iii)C. (i) and (ii)D. (ii) and (iv)

Answer» Correct Answer - C
The female gametophyte or embryo sac is located inside the insigde the nucellus, enclosed within the integuments . In a majority of flowering plants, one of the megaspore is functional while the other three degenerate. Three repeated mitotic divisions of the functional megaspore results in the formation of seven-celled or eight-nucleate embryo sac.
Six of the eight nuclei are organised at the two poles. Three cells grouped at micropylar end forms egg-apparatus and 3 at the chalazal end forms anripodal cells . The large central cell at the centre has two polar nuclei.
The meiotic divisions in the formation of embryo sac are strictly free nuclear, that is nuclear divisions are not followed immediately by celll-wall formation. Gametophyte is situated at micropylar end not at chalazal end .
Discussion
4.

What is self-incompatibility ?

Answer» It is a genetic mechanism which prevents self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
Discussion
5.

Embryo sac is to ovule as_________is to an anther.A. stamenB. filamentC. pollen grainD. androecium

Answer» Correct Answer - C
The pollen grains represent the male gametophytes. As the anthers mature and dehydrate, the microspores dissociate from each other and develop into pollen grains. So embryo sac is to ovule as pollen grains is to an anther.
Discussion
6.

The outermost and innnermost wall layers of microsporangium in an anther are respectivelyA. Endothecium and tapetumB. Epidermis and endodermisC. Epidermis and middle layerD. Epidermis and tapetum

Answer» Correct Answer - D
A typical microsporangium is generally surrounded by forr-wall layers , I.e., the epidermis, (outermost protective layer), endothecium, (middle fibraus layers) and the tapetum (innermost nutritive layer).
Discussion
7.

In an embryo sac, the cells that degenerate after fertilisation areA. synergids and primary endosperm cellB. synergids and antipodalsC. antipodals and primary endosperm cellD. egg and antipodals

Answer» Correct Answer - B
In unfertilised embryo sac, the antipodals and synergids are distinctly present at chalazal end and micropylar end respectively while in fertilised embryo sac antipodals and synergids gradually degenerate after the formation of zygote. (Also, refer to Q. 14)
Discussion
8.

Name the type of pollination in self-incompatible plants.

Answer» In self-incompatible plants , (while self-pollination is incompatible) cross-pollination is occurs.
Note: Self-incompatibility is a genetic mechanism which prevents self-pollen from fertilising the ovules by inhibiting pollen germination or pollen tube growth in the pistil.
Discussion