Human chorionic gonadotropin (hCG) is known to facilitate attachment of blastocyst to uterus. In women with a mutation in the hCG gene, biologically inactive hCG was formed but implantation occurred. When hCG was immuno-neutralized in the uterus of a normal woman, implantation failed. This suggests that for implantation in humans:

• biologically active circulating hCG is not required.

• blastocyst can produce the required hCG, which helps locally in uterine attachment.

• trophoblastic cells do not require hCG for the invasion of the uterus.

• extra-embryonic tissue is not responsible for the attachment of the embryo to the uterus.

During reproductive development in plants:

(A) male and female gametes are produced as a result of two mitotic division after meiosis.

(B) vegetative cell sin pollen contribute to pollen development.

(C) antipodals provide nourishment to developing embryos.

(D) pollen tube ruptures and releases both the male gametes in on of the degenerated synergids.

Which of the above statements are true?

• (A) and (B)

• (B) and (D)

• (B) and (C)

• (A) and (D)

During fertilization in mammals, sperm-egg interaction is mediated by zona pellucida (ZP) membrane proteins and their receptors present in the sperm membrane. ZP3 has been identified to be the principle ZP protein whose post-translational modification is important for sperm-egg interaction. In a competitive inhibition assay the sperm is saturated with either active ZP3 or its modified forms, before studying sperm-egg interaction. Which of the following experiments will NOT inhibit sperm-egg interaction?

• Saturate sperm with ZP3 protein prior to use.

• Deglycosylate the ZP3 protein and use it for saturation of sperm.

• Phosphorylate the ZP3 protein and use it for saturation of sperm.

• Dephosphorylate the ZP3 protein and use it for saturation of sperm.

If an Arabidopsis plant, mutated in lycopene biosynthetic pathway is grown in a sunny tropical climate in the presence of oxygen:

• it would accumulate higher biomass due to higher rate of photosynthesis

• there will not be any influence of this mutation on the rate of photosynthesis and plant growth.

• it would show reduced biomass due to photo-oxidative damage

• the leaves would be bluish-purple in color because of the higher accumulation of xanthophylls.

55.

In bone marrow, stem cells are committed to different lineages. Factors that stimulate the colonies of these different lineages are interleukin-3 (multi-CSF), granulocyte-macrophage colony-stimulating factor (G-CSF or M-CSF). In a mouse deficient in GM-CSF, the number of hematopoietic cells will be altered. Which one of the following is correct?

• Mast cells will be normal in normal while granulocytes and macrophages will be deficient in number.

• Granulocytes count will be normal but not of macrophages

• Macrophage number will remain unaltered.

• Mice will be deficient in all the three cell types.

Which of the following is NOT an advantage to seed-based reproduction?

• Reserve food material is provided for the developing embryo.

• Seed coat protects the embryo and allows it to remain dormant until favourable environmental conditions are available.

• The amount of energy spent per female gametophyte is less than that spent on making a spore.

• The female gametophyte remains on the sporophyte which provides protection and nourishment.

A plant with blue-coloured flowers was observed to attract a large number of pollinators. However, these flowers were not producing any nectar. Which of the following canbe a logical explanation to be observation?

• There could be another species in the vicinity that has blue flowers and is rich in nectar.

• There is no other species with blue flowers in the vicinity so pollinators are compelled to visit this species.

• Pollinators may not have blue-colour vision.

• Pollinatory may be able to see only blue colour

The change in the state of specification of the imaginal disc of Drosophila to that of a different disc type is known as

• transdetermination

• transdifferentiation

• transformation

• transduction

During double fertilization in plants, one sperm fuses with the egg cell and the other sperm fuses with

• synergid cell

• central cell

• antipodal cell

• nuclear cell

Over-expression of a dominant-negative FGF receptor during amphibian development would prevent formation of

• trunk and tail

• head and trunks

• trunk and fore limbs

• head and forelimbs