Zoology MCQs for NEET — Practice Questions with Answers

(c) The activated spermatozoan on reaching the egg plasma membrane, undergoes a number of changes in its acrosomal region. All these changes are collectively described under acrosome reaction. Acrosome reaction is calcium-dependent involving massive uptake of calcium with an efflux of hydrogen generating high pH and osmotic pressure, producing negative surface charge, and
partial or total release of the acrosomal enzymes Calcium influx may activate phospholipase
resulting in accumulation of unsaturated fatty acids and fusiogenic lysophospholipids contributing to
acrosome reaction

(b) Grey crescent is the area just opposite to the site of entry of sperm into ovum. It marks the future dorsal side of the embryo. 

(a) During follicular phase (proliferative phase), follicle stimulating hormone (FSH) secreted by anterior lobe of the pituitary gland stimulates the ovarian follicle to secrete estrogens. Corpus luteum secretes large amount of progesterone in secretory phase. Both LH and FSH attain a peak level in the ovulatory phase.

(d) Humanchorionic Gonadotropin (hCG) is secreted by the placenta for maintaining corpus luteum. Its presence in urine indicates pregnancy.

(d) Atretic follicles are found in the ovary. The ovary of an adult female has about 120,000-160,000
follicles. Out of which, only one ovarian follicle matures every 28 days alternatively by the two ovaries. The rest of them degenerate at different times. These are known as atretic follicles and the degeneration process is called follicular atresia

(b) Oxytocin is released from the interior portion of pituitary gland, which induces parturition.

 During the 1970s, researcher discovered that umbilical cord blood could supply the same kinds of blood-forming (haematopoietic) stem cells as a bone marrow donor and so cord blood began to be collected and stored. Cord blood stem cells also have the potential to give rise to other cell types in the body.

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Section 3.1 The Male Reproductive System

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Section 3.1 The Male Reproductive System

Page number-43, para-2, Section 3.1 The Male Reproductive System