Test: Human Reproduction - 1 - NEET MCQ

Primary oocyte undergoes first meiotic division to produce one secondary oocyte (egg cell) and first polar body (nonfunctional cell). Secondary oocytes complete meiosis II and produce one functional ovum and a second polar body. First and second polar bodies are nonfunctional cells; so, oogenesis produces one functional egg cell in each round. Thus, the correct answer is A.

• The menstrual cycle is a monthly cycle in which the primate females ovulate once in a month.
• Menstruation is important because it prepares the body for the fertilization and is a key process in reproduction.
• The cycle occurs in humans, chimpanzees and Orangutans, gorillas and monkeys.
• Other mammals have a similar cycle which is known as the oestrous cycle.

Androgens, in turn, stimulate the process of spermatogenesis. FSH acts on the Sertoli cells and stimulates secretion of some factors which help in the process of spermiogenesis.

• During birth, prostaglandins initiate the contraction in smooth muscles of uterine wall which causes labor pains.
• The pressure of fetus’s head against the cervix and send signals to make hypothalamus to trigger the release of oxytocin from the posterior pituitary. Together, oxytocin (OT) and prostaglandins stimulate strong uterine muscle contraction forcing the fetus downwards and thereby expelling it out of the uterus. Thus, to hasten the childbirth, it is advisable to administer the hormone that stimulates uterine smooth muscle contraction i.e. oxytocin. This makes option A correct.

• One primary oocyte will form one secondary oocyte and one polar body. One secondary oocyte will further form one ovum and one polar body and 1st polar body will produce two more polar bodies.
• So 1 primary oocyte will eventually form one ovum. So, 100 primary oocytes will form 100 eggs.

- At the end of meiosis I females have two daughter cells and meiosis II only occurs if and when the fertilization occurs by the sperm cell.
- Meiosis II starts after the sperm proceeds fertilization process in female 

• Sperm can be divided into 4 parts namely: head, neck, middle piece and tail.
• The haploid nucleus is present in the head.
• Acrosome is the cap-like structure of head which helps it to fertilize the ovum.

After fertilization, the zygote undergoes cleavage and divisions, thereby forming the blastocyst, which gets implanted in the endometrium of the uterus. The blastocyst then divides further and develops inside the uterus only. The uterus is the womb and is a major female reproductive hormone. Thus, the correct answer is option b.

The follicular phase of the female menstrual cycle includes the maturation of ovarian follicles to prepare one of them for release during ovulation. During the same period, there are concurrent changes in the endometrium, which is why the follicular phase is also known as the proliferative phase.

As in the case of any other cell, sperms are enveloped by a phospholipid bilayer, which is also called as plasma membrane or cell membrane.

Corpus luteum is the structure which is formed by the follicles after the egg is released from the Graafian follicle. This is a yellow coloured structure which is present in the ovary. The corpus luteum is the structure which is responsible for the release of the hormone progesterone. This is known as the pregnancy hormone which causes changes in the ovary and increasing the cell lining in the uterus. The hormone helps in maintaining pregnancy. 

The lower portion of the uterus forms a narrow structure which forms the cervix. The cervix extends to form the birth canal through which the fetus comes out during parturition. The vagina forms the opening of the birth canal. These two structures together are referred to as the birth canal or passage.

Oxytocin is a hormone that acts on organs in the body and as a chemical messenger in the brain, controlling key aspects of the reproductive system, including childbirth and lactation, and aspects of human behaviour. Oxytocin is produced in the hypothalamus and is secreted into the bloodstream by the posterior pituitary gland. The posterior pituitary does not produce any hormones of its own, rather, it stores and secretes two hormones made in the hypothalamus— oxytocin and antidiuretic hormone. Oxytocin stimulates the uterine muscles to contract and also increases the production of prostaglandins, which increase the contractions further.

The trophoblast layer plays a crucial role in the early stages of embryonic development by forming the outer layer of the blastocyst, which later contributes to the development of the placenta. This layer facilitates nutrient and waste exchange between the mother and the developing embryo, which is essential for the embryo's growth and development.