Chapter 3: Human Reproduction

Ans: Correct Option is c.

Internal fertilization is the type of fertilization during which union of egg and sperm nuclei occurs inside the body of a parent i.e., internally. This occurs in birds, mammals, and reptiles. 

Colostrum is the first milk produced after giving birth to a young one by the mother. It is a yellow-colored milk secretion which contains a large number of antibodies viz. IgA and nutrients to nourish the young one. It is a very important meal for a newborn and must not be discarded.

Polyspermy i.e., fertilization of one egg by many sperms is prevented in mammalian eggs by the process of depolarization. The egg, after being fertilized or entered in by one sperm nucleus, gets depolarized at the plasma membrane due to certain reactions. This helps to prevent any additional sperm from entering the egg cell and hence, polyspermy. It is, therefore, not prevented by chemical changes but changes in electrical potentials of the plasma membrane of the egg surface.

In the human female, implantation is bound to occur after 7-10 days of fertilization as the zygote form makes its way through the fallopian tube to uterus and then to the implantation site in the endometrium. 

Ans: Correct option is d.

The high level of LH or FSH triggers the ovulatory surge. The oogonial cells help to proliferate in the middle of a regular cycle from puberty. The sperms released from seminiferous tubules are pooly motile hence it is also incorrect.The statement d is correct as there is a considerably higher level of the hormone progesterone during the postovulatory phase of the menstrual cycle during which the follicle after rupture turns into corpus luteum. The corpus luteum is a steroidogenic cluster of cells which is yellow in color and secretes progesterone mainly. Hence option d is the correct answer.

Ans: Correct Option is d.

Rete testis is the part or a network of tubules just outside the seminiferous tubules located at the hilum of testis and carries the spermatozoa produced in seminiferous tubules to vasa efferentia.

Epididymis is a part of male reproductive that carries sperms towards the vas deferens from the vasa efferentia of testis. In this, the sperms have very less motility and aren’t mature.

Vasa efferentia is a part of male reproductive system too, which is a carrier of spermatozoa from the rete testis

Isthmus, on the other hand, is a part of the fallopian tubes of female reproductive system constituting the distal portion of an oviduct. It receives the egg after it is released from the ovary by the help of fimbriae.

Ans: Correct Option is b.

The liquid part of the semen or the seminal plasma is formed by the accessory parts of male reproductive system i.e., seminal vesicles, prostate gland and bulbourethral gland. The urethra however, only acts as a conduit for the movement of semen to the outside during ejaculation. Seminal vesicles provide citric acid, fructose, prostaglandins, and fibrinogen while the prostate gland provides calcium and phosphate ions to the seminal plasma of the males as the sperms pass through or by these glands. Bulbourethral gland secrete alkaline mucus which is a vital secretion for penile lubrication during the act of semen passage. All these three accessory glands make the semen qualitatively good for survival in the female reproductive tract.

Ans: Correct Option is a.

Spermiation refers to the process of release of spermatozoa from seminal or seminiferous tubules from where these cells are transferred to epididymis via vasa efferentia. The sperms mature in the epididymis of the male reproductive pathway.

Ans: Correct option is b.

Graafian follicle is the fully grown secondary oocyte which is present in the stroma of the ovary and on maturation, it bursts leading to the release of secondary oocyte from the ovary which is then transferred to the fallopian tubes. The Graafian follicle ruptures only after its complete maturation and a mature follicle in the ovary can be seen at arounf 11-17 day of the menstrual cycle of a human female which is just before the middle of the cycle when ovulation i.e., Graafian rupture occurs.

Ans: Correct option is a.

Acrosomal reaction is referred to the release of various contents of acrosome viz. hyaluronidase, corona penetrating enzymes, etc. when the acrosome at the head of a spermatozoa comes in contact with the zona pellucida of the ova, an outer layer of the egg. The acrosomal contents help the spermatozoa penetrate zona pellucida and corona radiata and reach plasma membrane of the ova.

Ans: Correct Option is b.

Male accessory glands are the secondary or accessory glands in a male reproductive system which even though secondary to the sperm producing structures, play a major role in the preparation of a qualitatively and chemically correct semen. The male accessory glands include prostate, seminal vesicle and bulbourethral glands. The ampulla is a part of fallopian tube or oviduct of a female reproductive system.

Ans: Correct Option is c.

In testis, on the inner walls of seminiferous tubules lie diploid cells called spermatogonia which divide by mitosis. Some of these cells are primary spermatocytes and thereafter undergo meiosis or reduction division to form haploid daughter cells called secondary spermatocytes having only one set of chromosomes. Each of these secondary spermatocytes’ form two spermatozoa of haploid ploidy by second meiosis and this is, in brief, the entire process of spermatogenesis. According to this, option c stands correct.

Ans: Correct Option is b.

A spermatozoan or a sperm cell can be divided into four different parts according to its anatomy:

The head contains the nucleus and is an elongated structure with acrosome at the tip of the head. The head mainly contains the genetic material in its nucleus so it matches with iv.

Middle piece consists of the neck and the central body or region of the sperm. The neck contains two nuclei whereas the body, which is cylindrical contains mitochondria, responsible for providing energy to the sperm when inside the female reproductive tract. Thus, this matches with iii.

Acrosome is present at the tip of a sperm cell and contains hydrolyzing enzymes which help it to penetrate zona pellucida i.e., it matches with i.

Tail is long, thin structure containing cytoplasm and helps in moving the sperm through the female reproductive tract thus it provides motility to the sperm and hence it matches with ii.