Test: Human Reproduction - 2 - NEET MCQ

• Gametes are formed by meiosis of germ cells. Hence, they are haploid.
• Gametes are produced through the process of meiosis.
• In males, gametes are produced in testes and in females, gametes are produced in ovaries.
• Since gametes are formed through meiosis, they undergo two set of divisions: meiosis I and meiosis II. 
• During meiosis, recombination occurs in which homologous pairs of chromosomes exchange their segments. Since gametes are formed through meiosis, therefore they have chromosomes that have undergone recombination.

• Primary oocyte completes the first round of meiosis in the tertiary oocyte, thus forming a secondary oocyte.
• The tertiary follicle further matures to form a Graafian follicle which ruptures and releases the secondary oocyte in the fallopian tube for fertilization.

Polar body is a small degenerate cell that forms after during oogenesis. During meiosis, the first polar body is formed when the secondary oocyte is formed. The polar bodies do not take part in fertilization.

• Primary follicle is formed by the primary oocyte arrested at Prophase I and enveloped by a layer of granulosa cells.
• These are then enveloped by a theca resulting in a secondary follicle, which further undergoes development resulting in the formation of a fluid-filled cavity called the antrum.
• This mature follicle is a tertiary follicle.

• The ovary is the place where the oocyte is developed from the oogonia.
• It houses follicles that nourish and protect eggs before they are released in the process of ovulation for fertilization.
• It also produces sex hormones like estrogen, which are essential for the development of secondary sexual characteristics in females.
• It does not hold the developing embryo.
• The embryo is held in the uterus.

After implantation, finger-like projections appear on the trophoblast called chorionic villi which are surrounded by the uterine tissue and maternal blood. The chorionic villi and uterine tissue become interdigitated with each other and jointly form a structural and functional unit between developing embryo (foetus) and maternal body called placenta.

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• Ovary has four different types of follicles, namely: Primary follicle, secondary follicle, tertiary follicle, and Graafian follicle.
• Hair follicles are present beneath the epithelium under the skin.

1. Ovulation - LH surge: Correct. Ovulation is triggered by a surge in luteinizing hormone (LH).
2. Follicular phase of menstrual cycle - Regeneration of endometrium: Correct. The follicular phase involves the regeneration of the endometrium.
3. Luteal phase - Secretion of FSH: Incorrect. The luteal phase is characterized by the secretion of progesterone, not follicle-stimulating hormone (FSH).
4. Menstruation - Withdrawal of progesterone: Correct. Menstruation occurs following the withdrawal of progesterone.

Therefore, the incorrectly matched pair is number 3: Luteal phase - Secretion of FSH.

Ovulation occurs about midway through the menstrual cycle, after the follicular/ proliferative phase, and is followed by the luteal phase.

The mitotic division starts as the zygote moves through the isthmus of the oviduct called cleavage towards the uterus and forms 2, 4, 8, 16 daughter cells called blastomeres.

The inner cell mass contains certain cells called stem cells which have the potency to give rise to all the tissues and organs.

• a. Hypothalamus → (iv) GnRH: The hypothalamus secretes GnRH (Gonadotropin-releasing hormone).
• b. Acrosome → (i) Sperm lysin: The acrosome in sperm contains enzymes like sperm lysin that help in penetrating the egg.
• c. Graffian follicle → (ii) Estrogen: The Graffian follicle is responsible for the production of estrogen.
• d. Leydig cells → (v) Testosterone: Leydig cells in the testes produce testosterone.
• e. Parturition → (iii) Relaxin: Relaxin is a hormone involved in the process of parturition (childbirth).

Thus, the correct matching is d (iv), b(i), c(ii), d(v), e(iii).

• The blastomeres in the blastocyst are arranged into an outer layer called trophoblast and an inner group of cells attached to trophoblast called the inner cell mass.
• The trophoblast layer then gets attached to the endometrium and the inner cell mass gets differentiated as the embryo.
• This is called implantation and it leads to pregnancy.
• After implantation, finger like projections appear on the trophoblast called chorionic villi which are surrounded by the uterine tissue and maternal blood.

In follicular phase:- FSH is responsible for ovarian growth and estrogen is responsible for thickening of endometrium.

During ovulation :-LH surge

In luteal phase:- LH surge  stimulates the formation of corpus luteum which in turn responsible for high progesterone  synthesis level and progesterone  maintain endometrium/uterine lining.

To identify the correct matching of hormones based on their roles during the menstrual cycle, let’s analyze each option:

1. FSH - Progesterone - LH - Oestrogen: Incorrect. FSH (Follicle-stimulating hormone) is involved in the early phase of the cycle, not directly linked to Progesterone.
2. LH - Progesterone - FSH - Oestrogen: Incorrect. LH (Luteinizing hormone) triggers ovulation, not directly linked to Progesterone.
3. FSH - Oestrogen - LH - Progesterone: Correct. FSH stimulates the growth of ovarian follicles, which produce Oestrogen. LH triggers ovulation, and the corpus luteum produces Progesterone.
4. LH - Oestrogen - FSH - Progesterone: Incorrect. LH and FSH roles are swapped here.

Therefore, the correct matching is Option 3: FSH - Oestrogen - LH - Progesterone.