Suppose you attend a town meeting at which some experts tell the audience that they have performed a cost-benefit analysis of a proposed transit system that would probably reduce overall air pollution and fossil fuel consumption. The analysis, however, reveals that ticket prices will not cover the cost of operating the system when fuel, wages, and equipment are taken into account. As a biologist, you know that if ecosystem services had been included in the analysis, the experts might have arrived at a different answer. Why are ecosystem services rarely included in economic analyses?

#Question id: 5662

#Unit 5. Developmental Biology

Mouse sperm contain receptor proteins that bind to a glycoprotein (ZP3) in the zona pellucida of mouse eggs. Binding of ZP3 receptors to ZP3 initiates the sperm’s acrosomal reaction. All of the following experimental observations would be expected EXCEPT:

#Question id: 5663

#Unit 5. Developmental Biology

Following statements are related to slow block to polyspermy in mammals.

A. A First slow block to polyspermy comes When the cortical granules fuse with the egg cell membrane, they release protein-digesting enzymes which is called as ovastacin that modify the zona pellucida proteins.

B. A second slow block to polyspermy comes from the so-called zinc spark, the release of billions of zinc ions that is induced by the entry of the first sperm, these released zinc ions are seen to bind to the egg cell membrane form a “zinc shield” that prevents further sperm entry.

C. A third slow block to polyspermy occurs at the level of the egg cell membrane and involves Juno.

Which of the following is incorrect?

#Question id: 5664

#Unit 5. Developmental Biology

Following statements are regarding to gamete fusion and the prevention of polyspermy in mammals.

A. In mammals, it is not the tip of the sperm head that makes contact with the egg but the side of the sperm head.

B. The junction between the inner acrosomal membrane and the sperm cell membrane is called the acrosomal region, and this is where membrane fusion between sperm and egg begins.

C. Sperm-egg fusion appears to involve several proteins, two of which are Izumo, in the oocyte membrane, and Juno, in the acrosomal membrane.

D. These fusion proteins bind together and appear to recruit other proteins to make an adhesion and fusion complex.

Which of the following statements are correct?

#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: 5666

#Unit 5. Developmental Biology

 When the extracellular side of the receptor binds resact, it activates latent guanylyl cyclase in the cytoplasmic side of the receptor. Active guanylyl cyclase causes the sperm cell to produce more cyclic GMP (cGMP), this compound_____

#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?