171.

Human sperms are allowed to fertilize ova having non functional ovastacin. The following possibilities may be of significance in the fusion of these gametes:

(a) The sperms will not fertilize ova.

(b) The sperms will blind and penetrate the zona pellucida but will not be able to fuse with ovum membrane.

(c) ZP2 will not be clipped by cortical granuel protease.

(d) CD9 protein of egg membrane microvilli will not be able to interact with sperm membrane proteins in the absence of ovastacin.

(e) Polyspermy may occur frequently.

Which combination of statements represent the outcome of the event?

(a) and (b)
(a) and (e)
(c) and (d)
(b) and (e)

172.

The zygote of C.elegans exhibits rotational cleavage. When the first two blastomeres formed (P1 and AB) are experimentally seperated, the following outcomes may be possible:

(a) The P1 cell in isolation generates all the cells it would normally make, showing autonomous specification

(b) The P1 cell in isolation generates all the cells it would normally make, showing conditional specfication

(c) The AB cell is isolation generates a small fraction of cell types it would normally make, showing conditional specification

(d) The AB cell in isolation generates a small fraction of cell types it would normally make, showing autonomous specification

Which one of the above combination of statements is true?

(a) and (c)
(b) and (c)
(b) and (d)
(a) and (d)

173.

Given below are some of the statements regarding regeneration:

(a) The type of regeneration characteristic of mammalian liver is considerd as Compensatory regeneration

(b) Regrowth of hair shaft from follicular cells exemplifies stem cell mediated regeneration

(c) Regeneration occuring through the repattering of existing tissues with little new growth is known as morphallaxis

(d) Adult structures undergoing dedifferentiation forming a blastema, that then redifferentiates to form the lost structure, is called epimorphosis

Choose the most appropriate combination of correct statements:

(d) only
(c) and (d) only
(a) , (b) and (c) only
(a) , (b) , (c) and (d)

174.
Following are certain statements regarding apomixis in plants:
(a) Apomixis cannot be used to mantain hybrid vigor over many generations in plants
(b) In sporophytic apomixis maternal genotype is maintained
(c) There is an event of meiosis during gametophytic apomixis and is also referred as apomeiosis
(d) In diplospory, meiosis of the megaspore mother cell is aborted, resulting in two unreduced spores, out of which one forms the female gametophyte
Which one of the following combinations is correct?

(a) and (b)

(a) and (c)

(b) and (c)

(b) and (d)

D.

(b) and (d)

Apomictic plants can also form embryos directly from a chromosomally unreduced female gametophyte (apomeiosis) in which the egg cell develops autonomously into an embryo by parthenogenesis ( gametophytic apomixis), by means of two types, apospory and diplospory. In apospory, the embryo and endosperm develop in unreduced embryo sac in the ovule. In this case, the megaspore mother cell in the sexual ovule starts to develop but stops at some stage, and one or more somantic cells in the ovule and their nuclei start to develop, resembling megaspore mother cells. Before the mature embryo sac formation, the megaspore or young embryo is aborted and replaced by developing aposporous sacs. Apospory is by far the most common mechanism in higher plants and has been reported in Beta, Brachiaria, Cenchrus, Chloris, Compositae, Eriochloa, Heteropogon, Heracium, Hyparrhenia, Hypercium, Panicum, Paspalum, Pennisetum, Poaceae, Ranunculus, Sorghum, Themeda and Urochloa.

Apomixis occurs in 500-600 species that belong to about 40 plant families and so is thought to have arisen multiple times during evolution. Consequently, there are also many different ways a clonal seed can be produced. In some species, such as citrus varities and mango (Magnifera indica), an embryo is formed directly from a sporophytic cell of the integuments and invades the embryo sac, competing with the sexually produced embryo. In such sporophytic apomixis, a diploid cell gives rise to the next generation, thereby maintaining the maternal genotype. Because this occur along-side sexual reproduction, sporophytic apomicts often produce a mix of clonal and sexual progeny.

175.

The following assumptions were derived from the above experiment:

(a) Medium A contained bFGF and PDGF.

(b) Medium b contained retinoic acid.

(c) Cells cultured in medium B were determined to become functional neurons prior to addition of the medium.

Which one of the following combinations represents correct statements?

(a) and (b) only
(a), (b) and (c)
(b) and (c) only
(a) and (c) only

176.

Following statements were made with respect to symbiotic association of rhizobia with legumes:

(a) nodD is regulatory gene.

(b) Nod factors are lipochitin oligosaccharides.

(c) Nod factors predominantly have α-1→ 4 linked N-acetyl-D-glucosamine backbone.

(d) Receptors for Nod factors are protein kinases with extracellular sugar-binding Lys M domain.

Which one of the following combinations represents all correct statements?

(a),(b) and (c)
(a),(c) and (d)
(b),(c) and (d)
(a),(b) and (d)

177.

In case of hydra, the major head inducer of the hypostome organizer is a set of Wnt proteins acting through the canoniocal β-catenin pathway. What would be the result, if a transgenic Hydra is made to globally misexpress the downstream Wnt effector β-catenin?

Ectopic buds will be formed all along the body axis and even on the top of the newly formed buds
Ectopic tentacles form at all levels
Both ectopic tentacles and buds would be formed along the body axis
There woulod be no change observed

178.

Both TGF-β are Sonic hedgehog signals play important roles in both neuralation and cellfate patterning of the neural tube. Which one of the following statements is true?