During embryo germination in a grass family, an absorptive organ that forms the interface between the embryo and the starchy endosperm tissue is called

• Coleorhiza

• Coleoptile

• Scutellum

• Mesocotyl

In Drosophila melanogaster males homologous chromosomes pair and segregate during meiosis but crossing over does not occur. At which stage of meiosis does segregation of 2 alleles of a gene meiosis does segregation of 2 alleles of a gene take place in these individuals?

• Zygotene

• Diakinesis

• Anaphase I

• Anaphase II

The following is a list of reproductive structures found in vascular and non-vascular plants.

A. Archegonia

B. megaspore

C. Capsule

D. Fern frond

E. Pollen

F. Corolla

Which of the following combinations represents structures primarily associated with the gametophytic life cycle of these plants?

• A, C, F

• A, B, E

• B, D, E

• C, D, F

A phenotypically normal fruitfly was crossed to another fl whose phenotype was not recorded. Of the progeny, 3/8 were wild type, 3/8 had ebony body color, 1/8 had vestigial wings and 1/8 had ebony body color and vestigial wings. Ebony body color and vestigial wings are recessive characters and their genes are located on two different autosomes. Based on this information which one of the following is the likely genotype of the parents?

• ee vgvg and e⁺e⁺ vg⁺vg

• ee vg⁺vg and e⁺e vg⁺vg

• e⁺e vgvg and e⁺e⁺vg⁺vg

• e⁺e vg⁺vg and e⁺e vg⁺vg

The following is a schematic representation of a hypothetical pathway involved in the formation of eye color in an insect species.

Genes A and B are linked and have a map distance of 10nM. Females with genotypes a⁺b⁺b are test crossed. Further, in these females, the two genes are linked in cis. a⁺ and b⁺ represent wild type alleles, while a and b null alleles. The progeny of the test cross have individuals with four different eye colors. What is the expected ratio of individuals with eye color Red: Vermillion: Brown: White in the progeny?

• 9: 3: 3: 1

• 1: 1: 1: 1

• 9: 1: 1: 9

• 1: 9: 9: 1

Consider the following facts regarding the control of shoot apical meristem (SAM) size in Arabidopsis.

(a) Loss of the CLAVATA1 (CLV1) gene leads to bigger SAM.

(b) Loss of the CLAVATA3 (CLV3) gene leads to bigger SAM.

(c) Loss of the WUSCHEL (WUS) gene leads to smaller SAM.

(d) Loss of both CLV1 and WUS leads to smaller SAM.

(e) Loss of both CLV3 and WUS leads to smaller SAM.

(f) Loss of both CLV1 and CLV3 leads to bigger SAM.

(g) Over expression of CLV3 leads to bigger SAM.

(h) Overexpression of CLV3 in the loss of function mutant of CLV1 leads to bigger SAM.

Based on the above information, which of the following genetic pathways describes the relationship among CLV1, CLV3, and WUS most appropriately?

Given below is a list of some proteins known to be associated with apoptosis, their sub-cellular localization (but not in correct order) and possible role in apoptosis.

Proteins	Localization	Role in apoptosis
A. Effector caspase	a. Cytosol	i. Promotes
B. Apaf-1	b. Cytosol, mitochondria	ii. Inhibits
C. Bax	c. Cytosol, nucleus

Choose the right combination which matches the proteins with their correct localization and role in apoptosis.

• A - a - ii; B - b - ii; C - c - i

• A - c - i; B - a - ii; C - b - ii

• A - b - i; B - c - ii; C - a - i

• A - c - i; B - a - i; C - b - i

The following are certain statements regarding stem cells:

A. All types of stem cells have the ability to give rise to a complete embryo.

B. Multipotent stem cells are those whose commitment is limited to a relatively small subset of all possible cell types.

C.Stem cell niches allow controlled self- renewal and also survival of the cells that leave the niche.

D. The pluripotency of the stem cells in an embryo is essentially maintained by Fgf8, Nanog and TGFβ.

E. Adult cells may be reprogrammed to gain pluripotency by modifying the following genes: Oct3/4, Sox2, c-myc, Klf-4.

Which one of the following combinations of statements is correct?

• A, B, and D

• B and E

• C and E

• A, C, and D

139.

When the 4 blastomere pairs of the 8-cell stage tunicate embryo are dissociated, each forms most of the structures it would have formed had it remained in the embryo. However, the notochord and nervous system get specified only if different blastomeres get the chance to interact. Given below are certain interpretations formulated from the above results:

A. Each pair of blastomeres forming respective structures indicate autonomous specification.

B. Each pair of blastomeres forming respective structures indicate conditional specification.

C. The notochord and nervous system development indicate autonomous specification.

D. The notochord and nervous system development indicate conditional specification.

Which combination of interpretations is most appropriate?

• A and C

• B and D

• A and D

• B and C

The presence of β-catenin in the nuclei of blastomeres in the dorsal portion of the amphibian embryo is one of the determinants for laying down the dorso-ventral axis. What will be the outcome of expressing a dominant negative form of GSK3 in the ventral cells of early embryo?

• The dorsal cells will be ventralized.

• A second axis will be formed.

• The primary organizer will not be formed.

• The embryo will develop normally.