101.

The following are some important features which are commonly associated with animals development:

A. Position of anus development with respect to blastopore.

B. Method of cell division.

C. Mechanism of coelom formation

D. Cleavage pattern during egg development.

Based on the above, which one of the following combinations differentiate the development of deuterstomes from that of protostomes?

• A, B, and C

• B, C, and D

• A, C, and D

• A and B

In C. elegans, an anchor cell and a few hypodermal cells take part in the formation of vulva. The experiments performed to understand the role of these cells in vulva formation and the results obtained are as follows:

-If the anchor cell is killed by laser beam, hypodermal cells do not participate in vulva formation and no vulva develops.

-If six hypodermal cells closely located with anchor cell (called vulval precursor cell) are killed, no vulva develops.

-If the three central vulval precursors are destroyed, the three outer cells, which normally form hypodermis, take the fate of vulval cells instead.

Following are certain statements regarding vulva formation:

A. Anchor cell acts as an inducer.

B. Six hypodermal cells with the potentiality to form vulva, form an equivalence group.

C. Three, out of six, hypodermal cells participate in vulva formation.

D. The central cell functions as the 1° cell and the two cells on both side act as the 2° cells.

E. The 1° cell secretes a short range juxtacrine signal.

Which combinations of the above statements have been derived from the above experimental results?

• A, B, and C

• A, B, and D

• D and E

• B, D, and E

The following are statements regarding the development and maintenance of anterior and posterior compartments in each segment of Drosophila:

A. Expression of wingless and engrailed is activated by pair-rule genes.

B. COntinued expression of wingless and engrailed is maintained by interaction between the cells expressing Engrailed and Wingless proteins.

C. Hedgehog is expressed in wingless expressing cells and forms short range gradient.

D. Hedgehog is a transcription factor.

E. Engrailed is a secretory factor and binds with the patched receptor of the wingless expressing cells.

Which one of the following combinations of above statements is correct?

• C and E

• C, D, and E

• D and E

• A and B

Following statements are made in relation to the five widely recognized stages of Arabidopsis embryogenesis:

A. The fusion of haploid egg and sperm takes place in Globular stage.

B. Rapid cell division in two regions on either side of the future shoot apex forms Heart stage.

C. The cell elongation throughout the embryo axis and further development result in Torpedo stage.

D. The embryo loses water and becomes metabolically inactive in the zygotic stage.

Which combination of the above statements is correct?

• A and B

• B and C

• C and D

• D and A

Successful fertilization in sea urchin demands specific interaction between proteins and receptors of sperms and eggs. In view of the above, which one of the following combinations is correct?

• Bindin in acrosomes and bindin receptors on the egg vitelline membrane.

• Bindin in egg membrane and bindin receptors in acrosomes.

• Resact on egg jelly and bindin on sperm membrane.

• Proteasomes on egg membranes and complex sugars on sperm membranes.

Instructive and permissive interactions are two major modes of inductive interaction during development. The following compares some properties of cell lines and cord blood stem cells. Cell lines, which are stored in liquid nitrogen, can be retrieved for experiments, where they behave as per their original self. Cord blood can also be retrieved from liquid nitrogen for procuring stem cells. Unlike cell lines, the stem cells can be additionally induced to undergo differentiation into desired lineages, which are very different from their original self. The behaviour of cell lines and stem cells is analogous to which of the interactions?

• Both cell lines and stem cells show instructive interaction.

• Cell lines show instructive interaction whereas stem cells show permissive interaction.

• Cell lines show permissive interaction whereas stem cells show instructive interaction.

• Both types of cells show permissive instruction.

You are asked to identify the stage of the estrus cycle in a vaginal smear of a mouse containing a large number of leukocytes and very nucleated epithelial cells. Which one of the following will be the correct stage of the estrous cycle?

• Early estrus, late proestrus

• Late estrus, early metestrus

• Late metestrus, early diestrus

• Late diestrus, early proestus

Floral organ development is controlled by overlapping expression of 'A' class, 'B'class, and 'C' class genes in different whorls. In an Arabidopsis mutant, the flowers had sepals, sepals, carpels and carpels in the four whorls. Mutation in which one of the following is the cause for the mutant phenotype?

• 'A' class gene alone

• 'B' class gene alone

• 'A' and 'B' class genes

• 'C' class gene alone

Migration of individual cells from the surface into the embryo's interior is termed as

• ingression

• involution

• invagination

• delamination

One hundered independent populations of Drosophila are established with 10 individuals in each population, of which, one individual is of Aa genotype and the other nine are of AA genotype. If random genetic drift is the only mechanism acting on these populations, then, after a large number of generations, the expected number of populations fixed for the "a" allele is

• 75

• 50

• 25

• 5