Chapter 3 Human Reproduction Textual Exercise Part -01

EXERCISES 

1. Fill in the blanks:

(a) Humans reproduce _____________

(asexually/sexually)

(b) Humans are _____________ 

(oviparous, viviparous, ovoviviparous)

(c) Fertilisation 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) Fertilisation 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 _____________

( ANS)

a.        Sexually

b.       Viviparous

c.        Internal

d.       Haploid 

e.       Diploid

f.        Ovulation

g.       Lutenising hormone

h.       Fertilization 

i.        Ampulla of oviduct

j.        Blastocyst

k.        Placenta

Question 03 .Draw a labelled diagram of male reproductive system.

Question 04 -Draw a labelled diagram of female

Already Answered  

2. Write two major functions each of testis and ovary.

   Ovary

•     During the process of oogenesis ovary produces ova.

•     Progesterone and oestrogen  , female sex hormones are secreted. 

Testis

•     During the process of spermatogenesis,  the sperm produced from seminiferous tubules.

•     Testosterone, male sex hormone are secreted. 

3. Describe the structure of a seminiferous tubule.

Each lobule contains one to three highly coiled seminiferous tubules in which sperms are produced. Each seminiferous tubule is lined on its inside by two types of cells called male germ cell (spermatogonia) and Sertoli cells.

The male germ cells undergo meiotic divisions finally leading to sperm formation, while Sertoli cells provide nutrition to the germ cells. The regions outside the seminiferous tubules called interstitial spaces, contain small blood vessels and interstitial cells . Leydig cells synthesise and secrete testicular hormones called androgens. Other immunologically competent cells are also present


 6. What is spermatogenesis? Briefly describe the process of spermatogenesis. 

• In testis, the immature male germ cell (spermatogonia) produce sperms by spermatogenesis that begins at puberty.  

• The spermatogonia (sing. spermatogonium) present on the inside wall of seminiferous tubules multiply by mitotic division and increase in numbers. Each spermatogonium is diploid and contains 46 chromosomes.  

• Some of the spermatogonia called primary spermatocytes periodically undergo meiosis. A primary spermatocyte completes the first meiotic division (reduction division) leading to formation of two equal, haploid cells called secondary spermatocytes, which have only 23 chromosomes each.  

• The secondary spermatocytes undergo the second meiotic.division to produce four equal, haploid spermatids . 

• The spermatids are transformed into spermatozoa (sperms) by the process called spermiogenesis. After spermiogenesis, sperm heads become embedded in the Sertoli cells, and are finally released from the seminiferous tubules by the process called spermiation. 

• Spermatogenesis starts at the age of puberty due to significant increase in the secretion of gonadotropin releasing hormone(GnRH).  

• The increased levels of GnRH then acts at the anterior pituitary gland and stimulates secretion of two gonadotropins – luteinising hormone(LH) and folliclestimulating hormone (FSH). LH acts at the Leydig cells and stimulates synthesis and secretion of androgens. Androgens, in turn, stimulate the process of spermatogenesis. FSH acts on the Sertoli cells and stimulates secretion of some factors which helps in the process of spermatogenesis.  


7-Name the hormones involved in regulation of spermatogenesis 

1.Lutenising hormone 

2.Gonadotropins 

3.Follicle secreting hormone 

4.Androgens  

5.Inhibition

Textual Exercise Part-02 Click Here