Development Biology MCQ - IIT JAM MCQ

Progesterone breaks the nuclear membrane of primary oocyte.

Epiboly in gastrulation movement which is characteristic by rolling of sheet of cells leading to its thinning and spreading of cell layers.

Fast block to polyspermy is activated after the fusion of first sperm with the egg and involve a change in electrical potential of egg membrane

Embryonic stem cells are pluripotent and derived from inner mass of blastocyst which is undifferentiated.

Nuclear determinants are called morphogens which determine morphogenesis.

Caudal gene shows its effect in anterior side also as bicoid won’t be able to inhibit its transcription. Hence, tail will form at both the sides.

The only cell that can give rise to a complete new organism is the fertilized egg (zygote) and this is described as totipotent

Concentration of BMP-4 is same at all the sides.   

In chick development, primary organizer is called Hensen’s node which forms the fate map further.

Agamous is present at the B and its mutation effect both petals and stamens.

During development, each cell is said to undergo autonomous specification i.e., if removed from the embryo, each cell develops according to its intrinsic instruction. It is also known as mosaic development.

This type of regeneration is called as morphallaxis.

Holoblastic cleavage:

1) Radial cleavage - Ampliioxus. Echinodenns 
2) Spiral cleavage - Annelids. Molluscs 
3) Bilateral cleavage - Tunicates
4) Rotational cleavage - Mammals. Nematodes

There are around 50 maternal genes which are involved in anterior-posterior axis specification, but out of the 50 genes, 4 genes are particularly important because their product form gradient along the axis and play important role.

Maternal effect genes have all the characteristic present in options.

Noggin is an antagonist of BMP and heeps in neural ectoderm not in skin ectoderm.

Morula is 16 celled stage.

As embryo development progresses to the 8 cell stage and beyond depending on the species, the individual blastomeres that comprise the embryo gradually lose their totipotency.

Both the gametes (either sperm or egg) from each parent should contain half the total number of chromosomes for that species. 

After second meiotic division the primary spermatocyte forms 4 haploid spermatids.