DIRECTIONS: This question contain STATEMENT-1 (Assertion) and STATEMENT-2 (Reason) and has 4 choices (a), (b), (c) and (d) out of which ONLY ONE is correct.
Statement 1 : Implantation is the process of attachment of blastocyst on uterine endometrium.
Statement 2 : Implantation is controlled by trophoblast and occurs by decidual cell reaction.
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Solution
The process of attachment of the blastocyst (mammalian blastula) on the endometrium of uterus is called implantation.
What happens during fertilisation in humans after many sperms reach close to the ovum?
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Solution
During fertilisation in humans, many sperms reach close to the ovum. As sperm comes in contact with the zona pellucida layer of the ovum it induces changes in the membrane that blocks the entry of additional sperm. The secretions of acrosome helps one sperm enter cytoplasm of ovum through zona pellucida.
If for some reason, the vasa efferentia in the human reproductive system gets blocked, the gametes will not be transported from
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Solution
If the vasa efferentia in the human reproductive system get blocked the gametes will not be transformed from testes to epididymis.
The first movements of the foetus and appearance of hair on its head are usually observed during which month of pregnancy?
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Solution
In human beings, after one month of pregnancy,the embryo’s heart is formed. By end of second month pregnancy,the foetus develops limbs and digits. By end of 12 weeks, major organ systems are formed. After fifth month, the first movement of foetus and appearance of hair on its head are observed. By the end of 24 weeks, the body is covered with hairs, eye lids separate and eyelashes are formed.
A change in the amount of yolk and its distribution in the egg will affect
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Solution
A change in the amount of yolk and its distribution in the egg will affect pattern of cleavage. In eggs with less yolk,cleavages are equal, and the resulting blastomeres are of similar size. If the yolk is localized, such as in frog eggs,then clevages are unequal, the cells derived from the yolky region (the vegetal pole) are larger than those derived from the region without yolk (the animal pole).
Foetal ejection reflex in human female is induced by:
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Solution
Foetal ejection reflex in human female is induced by fully developed foetus and placenta. When a woman is in a lithotomy or semi-sitting position, the foetal ejection reflex is impaired and the increased pain caused by the sacrum’s inability to move as the baby descends can be untolerable.
Which extra-embryonic membrane in humans prevents desiccation of the embryo inside the uterus?
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Solution
Amnion is an extra embryonic membrane in human prevents desiccation of the embryo inside the uterus. Amnion is a membrane that encloses the embryo of reptiles, birds and mammals within the amniotic cavity.This cavity is filled with amniotic fluid, in which the embryo is protected from dessication and from external pressure.
The milk-ejection reflex is stimulated by
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Solution
Prolactin stimulates the milk production and oxytocin stimulates the myoepithelial cells, which cause the milk-ejection reflex.
Fertilization occur in
Structure connecting the foetus to placenta is