Some given statements about Auxin signalling pathways are listed;

a) The auxin receptor is composed of two proteins: the SCF complex component TIR1 and the repressor protein AUX/IAA

b) The binding of auxin to its receptor complex initiates ubiquitin-dependent degradation of the AUX/ IAA repressor protein by the 26S proteasome 

c) TIR1 recruits AUX/ IAA proteins to the SCFTIR1  complex in an auxin-independent manner

d) AUX/IAA proteins are ubiquitinated by the E3 ligase activity of the SCFTIR1 complex, which marks the protein for destruction by the 26S proteasome

Which of the following is correct explanation of Auxin signalling pathways?

#Question id: 5684

#Unit 5. Developmental Biology

Capacitated mammalian sperm can sense thermal differences as small as 0.014ºC over a millimeter and tend to migrate toward the higher temperature. This ability to sense temperature difference and preferentially swim from cooler to warmer sites is called as _____1___ found only in ______2____ sperm.

#Question id: 5685

#Unit 5. Developmental Biology

Human sperm are allowed to fertilize ova having non- functional ovastacin. The following possibilities may be of significance in the fusion of these gametes:

A.        The sperms will not fertilize ova.

B.        The sperms will bind and penetrate the zona pellucida but will not be able to fuse with ovum membrane.

C.        ZP2 will not be clipped by cortical granule protease.

D.        CD9 protein of egg membrane microvilli will not be able to interact sperm membrane proteins in the absence of ovastacin.

E.         Polyspermy may occur frequently.

Which combination of statements represent the outcome of the above event?

#Question id: 5686

#Unit 5. Developmental Biology

Following statements are regarding to double fertilization in angiosperms.

A. One sperm cell fuses with the egg cell to produce the zygote that will develop into the new embryonic plant.

B. The second sperm cell fuses with the usually binucleate central cell, giving rise to the

endosperm, the tissue that nourishes the developing embryo. This second event is not “true” fertilization in the sense of male and female gametes undergoing fusion.

C. The second sperm cell fuses with the usually binucleate central cell, giving rise to the

endosperm, the tissue that nourishes the developing embryo. This second event is “true” fertilization in the sense of male and female gametes undergoing fusion.

D. During fertilization in angiosperm, when the sperm cells are released, the egg undergoes a flux of Ca2+. Then, chemicals released from the egg appear to make the sperm competent for cell fusion.

Which of the following statements are true?

#Question id: 28248

#Unit 5. Developmental Biology

The interaction of sperm and egg generally proceeds in a particular sequence manner, select the correct sequence; 

#Question id: 28249

#Unit 5. Developmental Biology

Acrosome is derived at the time of maturation from which organelles?

#Question id: 28250

#Unit 5. Developmental Biology

The major motor protein of the flagellum of sperm is