BIOLOGY 2 Marks Questions

a. Clot buster - Streptokinase, microorganism - Streptococcus
b. Cyclosporin A, Trichoderma polysporum
c. Statins, Monascus purpureus.

1. A-Spermatogonia,
B-Interstitial cells
C-Spermatozoa.
2. A-Spermatogonia produces a spermatogonium (plural: spermatogonia) is an undifferentiated male germ cell. Spermatogonia undergo spermatogenesis to form mature spermatozoa in the seminiferous tubules of the testes.
D-Sertoli cells provide nutrition to sperms.

i. Pollen release and stigma receptivity not synchronised, either pollen released before the stigma is receptive or otherwise.
ii. Anther and stigma are placed at different position, stigma cannot come in contact with the pollen of the same flower.
iii. In some plant flowers are unisexual, male flower and female flower born on different plant.
iv. Self incompatibility, it is a genetic mechanism and prevents self pollen from fertilising the ovule by inhibiting pollen germination or pollen tube growth in the pistil.
v. Many angiosperms possess genetic mechanisms that prevent self-pollination through self-incompatibility systems. These systems recognize and reject pollen from the same plant, promoting cross-pollination.

i. A - DNA polymerase, B - hnRNA, C - Spliced RNA, D - mRNA
ii. hnRNA is required to undergo splicing because of the presence of introns in it. These need to be removed and the exons have to be joined in a specific sequence for translation to take place.

The following microorganisms are used as biofertilizers:
i. Rhizobium: They form root nodules in leguminous plants and fix the atmospheric nitrogen into an organic form. Rhizobium also has no negative effect on soil quality and improves the quality, nutrient content, and growth of the plant.
ii. Azotobacter: These are free-living nitrogen fixers found in all types of upland crops. These not only fix nitrogen but also provide certain antibiotics and growth substances to the plant.