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TLS Online TPP Program

#Question id: 12836

The final layer of control that is critical in the regulation of CDKs is a family of proteins known as CDK inhibitors, or CKIs, which bind directly to the cyclin-CDK complex and inhibit its activity. Which of the following function not done by CKIs?

#Unit 2. Cellular Organization
  1. Binding of INK4s to CDK4 and CDK6 blocks their interaction with cyclin D and hence their protein kinase activity. 
  2. p27 prevents the premature activation of S phase CDKs during G1.
  3. p21CIP plays an important role in the response of metazoan cells to DNA damage by inhibiting G1/S phase CDKs and S phase CDKs, and thereby blocking entry into or passage through S phase.
  4. During ongoing DNA replication and in response to replication stress (slow DNA replication fork movement or DNA replication fork collapse), the ATR-Chk1 protein kinase cascade phosphorylates and inactivates Cdc25C, thereby preventing the activation of mitotic CDKs and inhibiting entry into mitosis.
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TLS Online TPP Program

#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?
TLS Online TPP Program

#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?
TLS Online TPP Program

#Question id: 6942

#Unit 5. Developmental Biology

How long does embryonic development (before 1st instar larva hatches) take in this organism?
TLS Online TPP Program

#Question id: 6943

#Unit 5. Developmental Biology

The portion of the blastoderm-stage embryo which will give rise to most ectodermal, mesodermal, and endodermal tissues is called the:
TLS Online TPP Program

#Question id: 6944

#Unit 5. Developmental Biology

Which would lead to a dorsalized embryo? (Recall that genes in Drosophila are named for their mutant phenotype.
TLS Online TPP Program

#Question id: 6945

#Unit 5. Developmental Biology

The portion of the Drosophila body plan which will produce the wing is called