#Question id: 5672
#Unit 5. Developmental Biology
Following statements are regarding to recognition of sperm by mammalian zona pellucida.
A. Sperm that have undergone the acrosome reaction bind directly to zona protein ZP2 and begin making a channel toward the oocyte.
B. Sperm with an intact acrosome bind to ZP2; they undergo the acrosome reaction on the zona pellucida and then transfer their binding to ZP3.
C. When a sperm reaches the oocyte and fuses with it, the cortical granules release proteins that digest portions of ZP2 and ZP3, making them nonfunctional and prevent polyspermy.
D. When a sperm reaches the oocyte and fuses with it, the cortical granules release proteins that digest ZP3 only, not ZP2 because ZP2 involve in the process of slow block to polyspermy.
Which of the above statements are correct?
#Question id: 5671
#Unit 5. Developmental Biology
Match the following mechanism of polyspermy (Column I) with events (Column II).
|
Column I |
Column II |
|
A. Fast block to polyspermy |
i. chemicals from the fusing sperm cytoplasm alter the sodium ion (Na+) channels on the membrane |
|
B. Slow block to polyspermy |
ii. enzyme cortical granule serine protease, cleaves the protein posts that connect the vitelline envelope |
|
iii the concentration of free Ca2+ in the egg cytoplasm increases |
|
|
iv. an electric change in the egg cell membrane |
|
|
v. the concentration of free Na+ in the egg cytoplasm increases |
Which of the following is correct?
#Question id: 5670
#Unit 5. Developmental Biology
Embryonic stem cells can be induced in the laboratory to differentiate into muscle, nerve, pancreatic, and other specialized cell types. It has recently become possible to trigger the dedifferentiation of somatic cells back into pluripotent cells (so-called induced pluripotent stem cells or iPS cells) by artificially enhancing the production of a relatively small number of key transcriptional factors known to be required for maintenance of pluripotency. Examples of such transcription factors are OCT4 and NANOG. The production of OCT4 and NANOG (and other key regulatory proteins) is stimulated by a transcription factor known as FOXP1, a member of the Forkhead family of DNA-binding proteins. There are two isoforms of FOXP1.
Which of the following statement regarding to FOXP1 is incorrect?
#Question id: 5669
#Unit 5. Developmental Biology
What is the reproductive difference between sea urchins and mammals is?
#Question id: 5668
#Unit 5. Developmental Biology
Following statements are made in relation to the five widely recognized stages of Arabidopsis embryogenesis:
A. The fusion of haploid egg and sperm takes place in zygotic stage
B. Rapid cell division in two regions on either side of the future shoot apex forms globular stage
C. The cell elongation throughout the embryo axis and further development result in Torpedo stage
D. The embryo loses water and becomes metabolically inactive in the torpedo stage
Which combination of the above statements is correct?
#Question id: 5667
#Unit 5. Developmental Biology
There may be an important connection between sperm translocation and capacitation. Which of the following option is correct explanation of above statement?