Biology

Human Reproduction

Question:

Why doctors recommend breast feeding during initial period of infant growth?

Answer:

The mammary glands of the female undergo differentiation during pregnancy and starts producing milk towards the end of pregnancy by the process called lactation.
The milk produced during the initial few days of lactation is called colostrum which contains several antibodies absolutely essential to develop resistance for the new bom babies. Breast-feeding during the initial period of infant growth is recommended by doctors for bringing up a healthy baby.

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Human Reproduction

Q 1.

Except endocrine function, what are the other functions of placenta?

Q 2.

Meiotic division during oogenesis is different from that in spermatogenesis. Explain how and why?

Q 3.

Write two major functions each of testis and ovary.

Q 4.

What are the major components of seminal plasma?

Q 5.

A human female experiences two major changes, menarche and menopause during her life. Mention the significance of both the events.

Q 6.

The mother germ cells are transformed into a mature follicle through series of steps. Provide the missing steps in the blank boxes.
ncert-exemplar-problems-class-12-biology-human-reproduction-10

Q 7.

What is parturition? Which hormones are involved in induction of parturition?

Q 8.

Describe the structure of a seminiferous tubule.

Q 9.

Match the following and choose the correct options:
ncert-exemplar-problems-class-12-biology-human-reproduction-4
Options:
(a) A—ii, B—i, C—iii, D—iv (b) A—iii, B—iv, C—ii, D—i
(c) A—iii, B—i, C—ii, D—iv (d) A—ii, B—iv, C—iii, D—i

Q 10.

Give the names and functions of the hormones involved in the process of spermatogenesis. Write the names of the endocrine glands from where they are released.

Q 11.

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 processes through which these events take place?

Q 12.

In our society the women are often blamed for giving birth to daughters. Can you explain why this is not correct?

Q 13.

Female reproductive organs and associated functions are given below in column A and B. Fill in the blank boxes.
ncert-exemplar-problems-class-12-biology-human-reproduction-8

Q 14.

Define spermiogenesis and spermiation.

Q 15.

The path of sperm transport is given below. Provide the missing.steps in blank boxes.
ncert-exemplar-problems-class-12-biology-human-reproduction-6

Q 16.

What role does pituitary gonadotropins play during follicular and ovulatory phases of menstrual cycle? Explain the shifts in steroidal secretions.

Q 17.

Why are menstrual cycles absent during pregnancy?

Q 18.

What is the role of cervix in the human female reproductive system?

Q 19.

Name the hormones involved in regulation of spermatogenesis.

Q 20.

Which type of cell division forms spermatids from the secondary spermatocytes?

Q 21.

(a) How many spermatozoa are formed from one secondary spermatocyte? (b) Where does the first cleavage division of zygote take place?

Q 22.

How many eggs are released by a human ovary in a month? How many eggs do you think would have been released if the mother gave birth to identical twins? Would your answer change if the twins born were fraternal?

Q 23.

What is the significance of ampullary-isthmic junction in the female reproductive tract?

Q 24.

What is the significance of epididymis in male fertility?

Q 25.

Mention the importance of LH surge during menstrual cycle.

Q 26.

How does zona pellucida of ovum help in preventing polyspermy?

Q 27.

Draw a labelled diagram of male reproductive system.

Q 28.

Name the functions of the following:
(a)Corpus luteum (b) Endometrium
(c)Acrosome (d) Sperm tail
(e) Fimbriae

Q 29.

Why doctors recommend breast feeding during initial period of infant growth?

Q 30.

Corpus luteum in pregnancy has a long life. However, if fertilisation does not take place, it remains active only for 10-12 days. Explain.

Q 31.

What are the major functions of male accessory ducts and glands?

Q 32.

From where the parturition signals arise”mother or foetus? Mention the main hormone involved in parturition.

Q 33.

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 processes through which these events take place?

Q 34.

How many eggs do you think were released by the ovary of a female dog which gave birth to 6 puppies?

Q 35.

What are the events that take place in the ovary and uterus during follicular phase of the menstrual cycle?

Q 36.

Match between the following representing parts of the sperm and their functions and choose the correct option.
ncert-exemplar-problems-class-12-biology-human-reproduction-2
Options:
(a) A”ii, B”iv, C”i, D”iii
(b) A”iv, B”iii, C”i, D”ii
(c) A”iv, B”i, C”ii, D”iii
(d) A”ii, B”i, C”iii, D”iv

Q 37.

Given below are the events in human reproduction. Write them in correct
sequential order: Insemination, gametogenesis, fertilisation, parturition, gestation, implantation

Q 38.

Draw a labelled diagram of female reproductive system.

Q 39.

Give a schematic labelled diagram to represent oogenesis (without descriptions).

Q 40.

Fill in the blanks:
(a)Humans reproduce————— (asexually/sexually).
(b)Humans are————— (oviparous, viviparous,ovoviviparous).
(c)Fertilization is————— in humans (external/internal).
(d)Male and female gametes are—————(diploid/haploid).
(e)Zygote is————— (diploid/haploid).
(f)The process of release of ovum from a mature follicle is called————— .
(g)Ovulation is induced by a hormone called—————
(h)The fusion of male and female gametes is called————— .
(i)Fertilization takes place in—————
(j)Zygote divides to form————— which is implanted in uterus.
(k)The structure which provides vascular connection between foetus and uterus is called————— .

Q 41.

What is spermatogenesis? Briefly describe the process of spermatogenesis.

Q 42.

Identify True/False statements. Correct each
false statement to make it true.
(a)Androgens are produced by Sertoli cells. (True/False)
(b)Spermatozoa get nutrition from sertoli cells. (True/False)
(c)Leydig cells are found in ovary. (True/ False)
(d)Leydig cells synthesize androgens. (True/ False)
(e)Oogenesis takes place in corpus luteum. (True/False)
(i) Menstrual cycle ceases during pregnancy. (True/False)
(g) Presence or absence of hymen is not a reliable indicator of virginity or sexual – experience. (True/False)

Q 43.

What is the difference between a primary oocyte and a secondary oocyte?

Q 44.

Draw a labelled diagram of a section through ovary.

Q 45.

What is the difference between a primary oocyte and a secondary oocyte?

Q 46.

What is foetal ejection reflex? Explain how it leads to parturition.

Q 47.

What are the changes in the oogonia during the transition of a primary follicle to Graafian follicle?

Q 48.

What is menstrual cycle? Which hormones regulate menstrual cycle?

Q 49.

Draw a labelled diagram of a Graafian follicle.

Q 50.

What is oogenesis? Give a brief account of oogenesis.