#Question id: 5665
#Unit 5. Developmental Biology
Following statements are regarding to cortical granule reaction.
A. To initiating the slow block to polyspermy the release of Ca2+ that occurs when the sperm enters the egg is critical for activating the egg’s metabolism and initiating development
B. Calcium ions release the inhibitors from maternally stored messages, allowing these mRNAs to be translated
C. Calcium ions are not release the inhibition of nuclear division, thereby allowing cleavage to occur.
D. Udx1, the enzyme responsible for the reduction of oxygen to crosslink the fertilization envelope, is also NADPH-dependent
E. The fertilization envelope is elevated from the cell membrane by glycosaminoglycans which provides support for the blastomeres during cleavage
Which of the following combinations are correct?
#Question id: 10680
#Unit 10. Ecological Principles
Which of the following organism usually show exploitation competition?
#Question id: 1385
#Unit 4. Cell Communication and Cell Signaling
The ability of a population of fibroblasts to migrate along the surface of a tissue culture dish depends on adhesion between the cell surface and the extracellular matrix molecules coating the dish. The dish is coated with laminin, and the only cell-surface protein capable of binding laminin is a cell-adhesion protein called an integrin. Integrins are integral plasma-membrane proteins that function as heterodimers. Under these conditions the rate at which a fibroblast can migrate along the laminin coated culture dish is proportional to the strength of adhesion between the cell and the laminin substrate. The table below lists the rate of cell migration observed for fibroblasts genetically engineered to generate the indicated phenotypes.
Which of the following is the most likely explanation for failure of overexpression of the integrin alpha subunit to alter the rate of fibroblast migration?
#Question id: 2975
#Unit 2. Cellular Organization
Following statements are regarding to the Surveillance mechanisms in cell cycle regulation.
A. Surveillance mechanisms known as checkpoint pathways establish dependencies among cell cycle events and ensure that the next cell cycle event does not occur prior to the completion of a preceding event.
B. In response to DNA damage, two related protein kinases, ATM and ATR, are recruited to the site of the damage, where they activate signaling pathways that lead to cell cycle arrest, repair, and under some circumstances, apoptosis.
C. The spindle assembly checkpoint pathway, which causes initiation of anaphase, utilizes Mad2 and other proteins to regulate APC/CCdc20, which targets securing and mitotic cyclins for ubiquitinylation.
D. The spindle position checkpoint pathway prevents mitotic CDK inactivation when the spindle is mispositioned. In this pathway, localized activators and inhibitors and a sensor that shuttles between them allow cells to sense spindle position.
Which of the following statement is incorrect?
#Question id: 12138
#Unit 10. Ecological Principles