20. The acrosome vesicle of the sperm and cortical granules of the human egg con
ID: 218638 • Letter: 2
Question
20. The acrosome vesicle of the sperm and cortical granules of the human egg contain ydrolytic enzymes. The acrosome reaction and the cortical granule reaction are mportant in mediating fertilization. The acrosome vesicle is located just above the spet nucleus and next to the cell membrane of the sperm cell, while the cortical granules are tound just beneath the egg cell membrane. Given this information, what predict to be the role for the hydrolytic enzymes in the context A: the h the sperm's genetic material to the egg pronucleus of fertilization. ydrolytic enzymes digest the egg's cell membrane creating a path to help deliver the hydrolytic enzymes selectively destroy the sperm thereby preventing polyspermy C: the hydrolytic enzymes digest and destroy the egg and the sperm to prevent fertilization D: the hydrolytic enzymes selectively destroy the egg preventing twin formation E: the hydrolyti sperm to fuse c enzymes neutralize one another to allow the fusion of the egg and the Ahich stage of embryonic development is associated with a hollow ball of cells? A. 3-layered gastrula B. blastula C. morula 21. D. zygote E. 2-layered gastrula 22. The trophoblast is mostly responsible for forming: A. placental tissue B. allantois C. lining of the endometrium D. archenteron E. chorion 23. Mesoderm gives rise to: A. intestinal mucosa B. nerves C. skin D. lung epithelium E. heart 24. During fertilization in invertebrates, what is the earliest event to occur in the process? A. sperm contacts the cortical granules around the egg B. sperm nucleic acid enters the egg's cytoplasm to form a pronucleus C. acrosome releases hydrolytic enzymes D. sperm contacts the vitelline membrane around the egg E. hyaluronic acid forms a barrier to prevent polyspermyExplanation / Answer
20. A. The hydrolytic enzymes digest egg cell membranes creating a path to help delivery of sperm's genetic material to egg pronucleus. Since the egg membranes act as barrier for the fusion of male and female gametes, the hydrolytic enzymes secreted from acrosome dissolve them.
21. B. Blastula. This stage marks the end of cleavage and is a hollow sphere of cells called blastomeres that surrounds fluid filled cavity, blastocoel.
22. A. Placental tissues. The trophoblast play important role in embryo implantation. The core placental villi is surrounded by trophoblast which covers the entire placenta and helps to generate contact between maternal and foetal blood. Hence they form lining cells or tissues of placenta.
23. E. Heart. Mesoderm mainly give rise to connective tissues one of which is heart.
24. C. Acrosome release hydrolytic enzymes. The sperm penetrates corona radiata followed by zona pellucida. This triggers the sperm to release enzymes for breaking zona pellucida.
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