One of the important functions of program cell death (PCD) in plants is protection against pathogens. PCD also appears to occur during the differentiation of xylem treachery elements that leads to nuclei and chromatin degradation. These changes result from the activation of certain genes. Following are certain genes encoding

A. Topoisomerase

B. Nuclease

C. RNA polymerase

D. Protease

Which one of the following combinations of the above is involved in differentiation of xylem treachery elements?

• A and B

• B and C

• C and D

• D and A

Light is crucial for plant growth and development. Following are certain statements related to photoreceptors in model plant Arabidopsis Thailand.

A. Among the five phytochrome genes, representing a gene family, PHYB plays a predominant role in red-light perception.

B. Cryptochromes are involved in the regulation of flowering time and hypocotyl length.

C. phyA photoreceptor is predominantly involved in far-red light perception.

D. The LOV domain of phytochrome C (phyC) is an important domain for signal transmission.

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

• A, B and D

• A, C and D

• B, C and D

• A, B and D

Following are certain statements regarding the activities of homeotic genes of classes A, B and C involved in floral organ identity:

A. Activity of A alone specified sepals.

B. Activity of B alone specifies petals.

C. Activities of B and C form stamens.

D. Activity of C alone specifies carpels.

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

• A, B and C

• A, B and D

• B, C and D

• A, C and D

A mutant embryo of Drosophila in which one of the major sex-determining genes, sex lethal, can only undergo default splicing, was allowed to develop. The following statements are towards explaining the determination of the sex of the embryo:

A. The embryo will develop into a male fly.

B. The embryo will develop into a female fly.

C. sex lethal gene product directly regulates sex-specific alternate splicing of double sex RNA.

D. sex lethal gene product regulates sex-specific splicing of transformer RNA which in turn regulates splicing of double sex RNA.

The correct combination of above statements to explain sex determination of the given embryo is:

• A and C

• A and D

• B and D

• B and C

85.

A two-celled embryo is made of blastomeres A and B. If the two blastomeres are experimentally separated, the 'A' blastomere generates all the cell it would normally make. However, the 'B' blastomere in isolation makes only a small fraction of cells it would normally make. Based on the above observations only, which one of the following conclusions is correct?

• 'A' blastomere is autonomously specified while 'B' blastomere is conditionally specified.

• 'A' blastomere is conditionally specified, while 'B' blastomere is autonomously specified.

• Descendents of 'A' blastomere are autonomously specified.

• Descendents of 'B' blastomere can either be autonomously specified or conditionally specified.

For utilization fertilization in sea urchin, interaction between the surface of the egg and acrosomal proteins, specifically a 30.5 kDa protein called bindin, is necessary. The following factors could affect this interaction and prevent fertilization:

A. Removal of egg jelly polysaccharides.

B. Removal of bindin receptors on the egg vitelline membrane.

C. Removal of bindin receptors from the egg jelly.

D. Removal of bindin receptors from a single cluster on the vitelline membrane.

Which one or the combination of the above statements is correct?

• A and B

• Only B

• A and B

• Only C

Schizocoelous coelom formation, mouth formation from embryonic blastopore, spiral and determine cleavage are characteristic of

• deuterostomes

• pseudocoelomates

• protists

• protostomes

The group of cells of amphibian blastula capable of inducing the organizer is called as

• Hensen's node

• Nieuwkoop center

• Dorsal blastopore lip

• Hypoblast

The splitting or migration or one sheet of cells into two sheets as seen during hypoblast formation in bird embryogenesis is termed as

• delamination

• ingression

• involution

• invagination

Which one of the following statements about LEAFY (LFY), a regulatory gene in Arabidopsis Thailand, is correct?

• LEAFY (LFY) is involved in floral meristem identity.

• LEAFY (LFY) is involved in leaf expansion.

• LEAFY (LFY) is involved in root meristem identity.

• LEAFY (LFY) is responsible for far-red light-mediated seeding growth.