During reproduction,the chromosome number (2n) reduces to half (n) in the gametes and again the original number (2n) is restored in the offspring.What are the process through which these events take place?

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(a)

1.Meiosis occurs during gametogenesis;it leads to reduction in  the number of chromosomes and haploid (n) gametes are formed.
2.During fertilisation,when two haploid gametes fuse,a diploid (2n) zygote is formed.

What stimulates pituitary to release the hormone responsible for parturition? Give the name of hormone.

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The signal from the fully developed foetus and placenta or the foetal-ejection reflex induces mild uterine contractions. The hormone released during this phase is oxytocin.

Cervix contains the largest and the strongest sphincter in its wall. Give reason.

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Cervix can hold about 7kg of foetus and fluid in the uterus against the pull of gravity for several days during pregnancy. Thus, it contains the largest and strongest sphincter.

Spermatogenesis is a continuous process but its release is not. How reproductive system does manage this situation?

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Sperms need to be stored in epididymus till they are to be released.

Based on the above question, explain that under what physiological conditions are the sperms managed and what changes are brought before their release?

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While storing sperms are kept in deactivated stage. The secretions of the glands contain fructose, ions, activation principles that restore the agility and activity.

Penis is considered to be a secondary sex organ; still its tube is called as urino-genital canal. Give reason for this consideration?

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The canal within the penis is common between urinary and genital systems.

Penis consists of soft tissue and this condition is of no use for insemination. How is this problem overcome during the reproductive physiology?

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Penis –soft tissue has spongy, vascular tissue which gets filled with blood and thereby generates hydrostatic pressure for .erection

The spermatozoas need to be activated for bringing out the act of fertilization. What role does accessory sex glands play in this process?

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(a)

Accessory glands release fructose, ions, and activation principles.

Ovaries are made of soft tissue and are not fixed in any bony socket but are placed in abdominal cavity. So there is a possibility that they may get displaced. But this generally does not happen. How is this attained?

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(a)

Ovaries do not normally get displaced due to attached on the mesenteries within the abdominal cavity.

Seminiferous tubules are the factories for the generation of spermatozoas, but they can’t work on their own. What stimulus do they get? Is the stimulus generated within the tubule or some where else?

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(a)

Hormonal stimulus – obtained from pituitary gland.

Spermatogenesis and spermatogenesis are two different processes but both are essential for male reproductive system. How do they differ from each other?

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Spermatogenesis is spermatogonia to spermatid, but spermeiogenesis is from spermatid to spermatozoa.

A sperm after being released in the vagina must reach the end of the fallopian tube to participate in the act of fertilization. What machinery comes into play for the said purpose?

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Sperm has to move so tail is required, mitochondria for energy generation, source of energy comes from the secretions.

Do LH and FSH have the same function in the male and female reproductive physiology? Justify your answer.

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LH in male stimulate Leidig cells to release androgens, but in females result in ovulation. FSH in males stimulates sertoli cells to release factors for spermeiogenesis but in females it stimulates a new follicle.

For completing the act of fertilization the sperm must fuse with the ovum, but the latter is surrounded by lot of extra follicular cells. How the sperm does manage to fuse with the ovum?

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(a)

Sperm acrosome release sperm lysins which digest the additional layers around the ovum.

Fertilization requires one male and one female gamete, but there are approximately 200 million sperms in a single ejaculation. How then the female reproductive system and the ovum ensure monospermy?

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(a)

Touching of the sperm at the right position on the ovum initiates a reaction that blocks the penetration of any further sperm thus polyspermy prevented.

The days of the menstrual cycle start with the onset of menses rather than with the end of menses. Give your justification for such a calculation?

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Day 01 starts with the start of menses as a new follicle gets stimulated i.e. a new cycle starts.

Placenta is an intimate connection between maternal and foetal tissues. It is a dual organ. Justify?

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Placenta- attachment, transport route and endocrine gland.

“After birth” is not the name of any proceeding to be executed after the birth of a baby, it is some thing else. Elaborate on the authenticity of the statement?

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After birth- the materials that are dislodged and expelled out of the uterus after the expulsion of baby.

The milk produced by the mother for the first few days is important for the baby not only energetically but also for some other reason. Elaborate on this statement?

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Colostrum is rich in defence molecules (antibodies) for the baby whose defenses are not mature enough to fight infections.

Observe the relationship between first two words and suggest suitable word for the fourth one 
(i) Ovary: Mesovarium: : Uterus: A
(ii) Male: Penis: : Female : B
(iii) Male gametes: Sperms: : Female gametes: C

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(a)

A-Pelvic wall, B-Clitoris, C-Ova.