31 Years NEET Previous Year Questions: Human Reproduction - 2 - NEET MCQ

The Fallopian tube is about 10-20 cm long and extends from the periphery of each ovary to the uterus. The part closer to the ovary is funnel-shaped and is called the infundibulum. The edges of the infundibulum possess finger-like projections called fimbriae, which help in the collection of the ovum after ovulation. the uterus opens into the vagina through a narrow cervix.

The testes are present in the scrotum which maintains the scrotal temperature below 2ºC of the internal body temperature.

If the vasa efferentiain the human reproductive system get blocked the gametes will not be transformed from testes to epididymis.

The part of fallopian tube closest to the ovary is infundibulum. Infundibulum possess finger-like projections called fimbriae that help in collection of ovum after ovulation. It leads to wider part of oviduct called ampulla. The last part of oviduct is isthmus that has a narrow lumen and joins the uterus.

Morula is a solid ball contained within the zone pellucida. It has almost equal quantity of cytoplasm as an uncleaved zygote but much more DNA.

Acrosome a small pointed structure at the tip of nucleus. It breaks down just before fertilization, releasing hydrolytic enzymes that assist penetration between follicle cells that surrounds the ovum, thus facilitating fertilization.

In Oogenesis, the second maturation division occurs until after the ovum has been penetrated by a sperm. Oogenesis involves the formation of haploid female gametes, ova, from this diploid egg mother cells, oogonia of ovary of female organism.

The development of the embryo is also known as embryogenesis. It includes both cell division as well as differentiation. The period until implantation occurs is known as the germinal stage. During this phase active cell division occurs. Leads to the formation of a blastocyst or blastula. The next stage is gastrulation. And later the various embryonic layers are formed. It is further followed by neurulation and organogenesis respectively. Different organs get formed and developed at different stages of pregnancy.
The fifth month of development is characterized by the movement of the fetus within the womb, the first movement shown by the fetus is called quickening. It is also characterized by the development of body hair. At this time, the muscles also start to develop.

Considering the other given options:
A.Third month, the arms, feet, toes, fingers, as well as hands, develop completely. The finer and toenails are starting to grow. The development of reproductive organs also starts. Thus it is not the right option.
B. In the fourth month, the heartbeat of the fetus can be listened to, through a Doppler test. The fingers, as well as toes, get completely formed. Thus it is not the right option.
D. In the sixth month, the fingerprints are formed. The eyes open, and the eyelids get separated. Thus it is not the right option.

Parturition is the process of delivery of the foetus. The signals for parturition originate from the fully developed foetus and placenta that induce uterine contraction called foetal ejection reflex. This triggers the release of oxytocin hormone from pituitary. This in turn leads to expulsion of the baby out of uterus.

Amniocentesis is a medical procedure in which amniotic fluid (the protective fluid seen around the foetus) is used to detect the genetic abnormality of the foetus.

This procedure can also be used to detect the sex of the unborn foetus, but, this is unethical and is not allowed to do. Therefore, the permissible use of the technique "amniocentesis" is detecting genetic abnormality.

Seminal plasma in human males are rich in fructose, calcium and certain enzymes. They provide a medium for transport of sperms, nourishes and activates sperms.

Sertoli cells are found in the walls of seminiferous tubules of the testes. They anchor and provide nutrition to the developing germ cells especially the spermatids.

In vitro fertilization (IVF) or test-tube baby technique involves fertilizing one or more eggs outside the body and then transferring the fertilized eggs known as pre-embryos back into the uterus. Zygote Intra Fallopian Transfer (ZIFT) is an example of IVF. In this, the zygote or early embryos upto 8 blastomeres are transferred into the Fallopian tube. If the embryo has more than 8 blastomeres then it is transferred into uterus called as IUT.

A change in the amount of yolk and its distribution in the egg will affect pattern of cleavage. The pattern of cleavage is influenced by the amount of yolk in the egg. In eggs with less yolk, cleavages are equal, and the resulting blastomeres are of similar size. If the yolk is localized, such as in frog eggs, then clevages are unequal, the cells derived from the yolky region (the vegetal pole) are larger than those derived from the region without yolk (the animal pole).

A high blood concentration of progesterone and oestrogen will delay or stop menstruation. A high concentration of sex hormone inhibits ovulation and implantation, as well as alter the quality of cervical mucus to prevent / retard entry of sperms. This happens because high concentration of circulating progesterones are an indication of successful conception and pregnancy. Hence, secretion of follicle stimulating hormone (FSH) and luteinizing hormone (LH) from pituitary is inhibited.

The formation of sperms in mature human testes completed in three important phases in gametogenesis- multiplication, growth and maturation phase. During these phases primarily germ cells change into spermatogonia then spermatocyte during growth phase which change into spermatoids and spermatids into sperms.

Foetal ejection reflex in human female is induced by fully developed foetus and placenta. When a woman is in a lithotomy or semi-sitting position, the Foetal Ejection Reflex is impaired and the increased pain caused by the sacrum’s inability to move as the baby descends can be intolerable.

The human male reproductive system consists of a number of sex organs that are a part of the human reproductive process. In diagram of male reproductive system of human, the point indicated by A,B,C,D are vas deferens, seminal vesicle, prostate and bulbourethral gland.

Seminal plasma is composed of the fluid and sperms from the vas deferens. The major components of the seminal plasma in the male reproductive system are mucus, spermatozoa, and various secretions of accessory glands. The seminal plasma is rich in fructose, calcium, ascorbic acid, and certain enzymes. It provides nourishment and protection to sperms.

The next phase of the menstrual cycle is the luteal or secretory phase. This phase always occurs from day 14 to day 28 of the cycle. Progesterone stimulated by LH is the dominant hormone during this phase to prepare the corpus luteum and the endometrium for possible fertilized ovum implantation.

The corpus luteum is essential for establishing and maintaining pregnancy in females. In the ovary, the corpus luteum secretes estrogens and progesterone, which are steroid hormones responsible for the thickening of the endometrium and its development and maintenance, respectively.

Each spermatogonium is produced from the premordial germ cell then actively grows to a larger primary spermatocyte. Each primary spermatocyte divides meiotically and produces haploid secondary spermatocytes. 

Amnion is an extraembryonic membrane in human prevents desiccation of the embryo inside the uterus. Amnion is a membrane that encloses the embryo of reptiles, birds and mammals within the amniotic cavity. This cavity is filled with amniotic fluid, in which the embryo is protected from dessication and from external pressure. 

In human female, the periodic discharge of blood, mucus and cellular debris from uterine wall from non-pregnant women of sexual maturity is known as menstrual cycle. Few hours before the start of mensuration, the spiral arterioles constrict one by one resulting into the blanch mucosa. The mucosa shrinks and the death of the blood deprived tissues takes place. 

Rete testis is connected to caput epididymis by 12-20 fine tubules called vasa efferentia or ductuli efferens. These collect sperms from inside the testis and transfer them to the epididymis. Vas deferens arises from caudal epididymis, conducts sperms from epididymis to urethra.

The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane. ... It is known as acrosomal reaction. Acrosome reaction results in dissolving of corona cells and degeneration of zona pellucida which helps in sperm penetration.