Chapter 2: Human Reproduction

Ans:

1. Humans reproduce sexually.

2. Humans are viviparous.

3. Fertilization is internal in humans.

4. Male and female gametes are haploid.

5. A zygote is diploid.

6. The process of release of the ovum from a mature follicle is called ovulation.

7. Ovulation is induced by a hormone called the luteinizing hormone.

8. The fusion of the male and the female gametes is called fertilization.

9. Fertilization takes place in the fallopian tube.

10. The zygote divides to form a blastocyst, which is implanted in the uterus.

11. The structure which provides a vascular connection between the foetus and uterus is called the placenta.

Solution coming soon.

Solution coming soon.

Ans: 

Functions of the Testis

• Spermatozoa are produced by the process of spermatogenesis.

• Male hormone called testosterone is secreted by the Leydig cell of the seminiferous tubules.

• The development of secondary sex characteristics in males is done by a hormone called Testosterone.

 Functions of the ovary

• By the process of oogenesis, the ovary produces a female gamete called ova.

• A female sex hormone called estrogen is secreted by the mature Graffian follicle. The development of secondary sex characteristics in females is done by a hormone called Estrogen.

Ans: Seminiferous tubules are a highly coiled structure where the production of sperms in the testes takes place. These tubules are located within the testicular lobules. The two types of cells namely spermatogonia and Sertoli cells are found in the germinal epithelial lining of seminiferous tubules. Spermatogonia produces primary spermatocytes by meiotic divisions which are male germ cells. Primary spermatocytes undergo further meiotic division to form secondary spermatocytes and eventually, spermatids. Spermatozoa are produced by the metamorphosis of the spermatids. Though the Sertoli cells provide nourishment to the germ cells, they are also referred to as nurse cells. The large polygonal cells known as interstitial cells or Leydig cells are present between the seminiferous tubules. Male hormone called testosterone is secreted by these cells.

Structure of Seminiferous Tubule

Ans: The production of sperms from the immature germ cells in males is referred to as spermatogenesis. It takes place in seminiferous tubules present inside the testes. During spermatogenesis, a diploid spermatogonium (male germ cell) increases its size to make a diploid primary spermatocyte. This diploid primary spermatocyte undergoes first meiotic division (meiosis I), which is a reductional division to form two equal haploid secondary spermatocytes. Each secondary spermatocyte then undergoes a second meiotic division (meiosis II) to form two equal haploid spermatids. Hence, four haploid spermatids are produced by a diploid spermatogonium. These spermatids by the process called spermatogenesis are transformed into spermatozoa (sperm).

Ans: Gonadotropin-releasing hormones secrete Follicle-stimulating hormones (FSH) and luteinizing hormones (LH) from the hypothalamus. In the process of spermatogenesis, these hormones are required. FSH acts on Sertoli cells, whereas LH acts on Leydig cells of the testis and stimulates The method of spermatogenesis gets stimulated by FSH and LH.

Ans: Spermiogenesis

It is the process of changing spermatids into mature spermatozoa or sperms.

The releasing of sperms from the Sertoli cells into the lumen of seminiferous tubules is called spermiation.

Solution coming soon.

Ans: Semen is the alkaline fluid ejaculated by man. It consists of sperms and seminal plasma. In the male reproductive system, its major components are mucus, spermatozoa, and various secretions of accessory glands. For the sperm to be active, the seminal plasma also contains fructose, calcium, ascorbic acid, and certain enzymes. Thus, nourishment and protection to sperms are provided.