NEET Biology Human Reproduction MCQs Set 12

Answer: (a) In seminal vesicle

Explanation:
1. Epididymis is a mass of coiled tubules attached to the posterior surface of the testes. It stores the sperms temporarily. Sperms achieve maturity and motility in epididymis by reabsorption of fluid secreted originally by the seminiferous tubules and by chemicals produced by the lining of epididymal tube.

Answer: (a) Androgens

Explanation:
1. Interstitial cell secrets androgen (testosterone). i.e., male sex hormones
2. Differences between Leydig’s cells and Sertoli cells

Answer: (a) Monozygotic

Explanation:
1. Identical or monozygotic twins are siblings that develop from one egg, contain identical genetical information and are usually of very similar appearance. Any physical and mental differences detected between identical twins must arise, therefore, from enviromental difference, both before or after birth.

Answer: (b) 14-16 days

Explanation:
1. Ovulation takes place in the menses between 14-16 days.
2. Menstrual cycle

Answer: (d) Ecroderm

Explanation:
1. Nervous system originated from ectodermal layer.

Answer: (c) A-Teratogens, B-thalidomide

Explanation:
1. Teratogens, which produces abnormality in the developing embryo.
2. Thalidomide is a drug which causes no or underdevelopment of the limbs (phoeomelia)

Answer: (c) Apoptosis

Explanation:
1. Apoptosis is an active process of programmed cell death, characterized by cleavage of chromosomal DNA, chromatin condensation and fragmentation of both the nucleus and the cell.

Answer: (b) Sperm lysins

Explanation:
1. There are many enzymes in the acrosome like fertilisin, hyaluronidase, pectin corona penetrating enzyme, acrosin etc., together they are called sperm lysins

Answer: (a) Sperm lysine

Explanation:
1. The enzyme present in sperm acrosome are collectively called sperm lysins and containing:
2. (i) Hyaluronidase: Acts on the ground substance of follicle cells.
3. (ii) Corona penetrating enzyme: Dissolve corona radiata.
4. (iii) Zona lysin or acrosin: It helps to digest the zona pellucida.

Answer: (c) Middle

Explanation:
1. Sperm has mitochondria at its middle part. This middle part gives energy for the motility to the sperm.
2. Structure of a sperm (spermatozoa) It consists of four parts i.e., Head, Neck, Middle piece and tail, enveloped by a plasma membrane.
3. Head It is the enlarged end of a sperm, containing the large haploid nucleus, i.e., condensed chromatin body and is capped by acrosome. The acrosome contains hydrolytic enzymes that help in dissolving membranes of the ovum for fertilization.
4. Neck It contains proximal centriole which is necessary for the first cleavage division of zygote and the distal centriole that is connected to the tail filament.
5. Middle piece It contains a number of mitochondria that provide energy for the movement of the tail that facilitate sperm motility essential or fertilization.
6. Tail It consists of axial filaments surrounded by the plasma membrane. It helps the sperms to swim in a fluid medium

Answer: (c) 12-15 days

Explanation:
1. A woman with typical 28 day of menstrual/cycle is most likely to pregnant during 12-15 day because it is the period in which ovulation takes place due to LH surge

Answer: (b) A- testis, B-glands, C-ducts, D- genitalia

Explanation:
1. A-Testis, B-Glands, C-Ducts, D- Genitalia

Answer: (b) A-200, B-300, C-7.35, D-7.50

Explanation:
1. Semen is collection of secretions from the seminal vesicles, prostate gland and Cowper’s glands and sperms from testis. A single ejaculation may contain 200-300 million spermatozoa (sperms) of which atleast 60% sperms must have normal shape and size and atleast 40% of them must show vigorous motility for normal fertility.
2. Semen has a pH of 7.35-7.50; its alkalinity helps to neutralize the acidity of the urethra protects the sperms from the acidity of the vagina

Answer: (c) Capacitation

Explanation:
1. Maturation of sperm before penetration of egg is called capacitation.
2. The development of spermatozoa from germinal cells is called spermatogenesis.
3. Spermiogenesis is the differentiation of spermatids into spermatozoa.

Answer: (c) LH and FSH

Explanation:
1. The corpus luteum secretes progesterone, which negatively feed back and inhibits the release of LH and FSH.
2. Generally, menstrual cycle have four phases
3. (i) Menstrual phase (a) The soft tissue of endometrial lining of the uterus disintegrates causing bleeding.
4. (b) The unfertilized egg and soft tissue are discharged.
5. (c) It lasts 3-5 days.
6. (ii) Follicular Phase/Proliferative Phase (a) The primary follicles in the ovary grow and become a fully mature Graafian follicle.
7. (b) The endometrium of the uterus is regenerated due to the secretion of LH and FSH from anterior pituitary and ovarian hormone, estrogen.
8. (c) It least for about 10-14 days.
9. (iii) Ovulatory Phase (a) Rapid secretion of LH (LH surge) induces rupture of Graafian follicle, thereby leading to ovulation (release of ovum).
10. (b) It lasts for only about 48 hr.
11. (iv) Luteal Phase/Secretor Phase (a) In this phase the ruptured follicle changes into corpus luteum in the ovary and it begins to secrete the hormone progesterone.
12. (b) The endometrium thickens further and their glands secrete a fluid into the uterus.
13. c) If ovum is not fertilized, the corpus luteum undergoes degeneration and this causes disintegration of the endometrium leading to menstruation.
14. (d) Oestrogen and progesterone levels rise during this phase. It lasts for only 1 day. (e) During pregnancy all events of the menstrual cycle stop and there is no menstruation. The menstrual cycle permanently stops in females at the age of around 50 years. This is called menopause

Answer: (a) Prenatal period

Explanation:
1. Development periodsIt includes embryonic or prenatal and post embryonic or postnatal (natal concerning birth)
2. (i) Embryonic period (prenatal period) In human beings is passed in mother’s womb (uterus). It includes the events from the formation of an embryo till the time of birth
3. (ii) Post embryonic period (postnatal period). This period is passed outside the mother’s womb. It includes events from birth to the death

Answer: (a) Golgi bodies

Explanation:
1. Acrosome is a cap-like structure surrounding the anterior end of the nucleus of a sperm. It is produced by the Golgi complex of spermatid. Acrosome of mammalian sperm produces sperm lysin called hyaluronidase.

Answer: (b) 14-16 days

Explanation:
1. Ovulation is the release of the secondary oocyte from the ovary. In humans, ovulation occurs about 14 days before the onset of the next menstruation.

Answer: (a) Proliferation of endometrium wall

Explanation:
1. Proliferation of endometrium.
2. In the ovulatory phase, both LH and FSH attain a peak level in middle of cycle (about 14 day). Rapid secretion of LH induces rupturing of Graafian follicle and thereby releasing the ovum in human beings (secondary oocyte is released). This is called ovulation. Infact increase level of LH causes ovulation

Answer: (a) Any types of cells

Explanation:
1. Stem cells are the cells, which can give rise to any type of cell. They are also called totipotent cells. They (stem cells) are found more abundantly in plants than animals

Answer: (a) Haploid ovum

Explanation:
1. Second meiotic division give rise to haploid ovum \((1n)\) and second polar body.
2. Oogenesis is the process of formation of mature ovum. It has three phases
3. (a) Multiplication Phase Oogenesis takes place in embryo stage. A couple of million of gamete mother cells (oogonia) are formed within each foetal ovary. No more oogonia are formed after birth. These cells (oogonia) get into prophase-I of meiotic division. They get temporarily arrested as this stage called primary oocyte
4. (b) Growth Phase Each primary oocyte then gets surrounded by a layer of granulosa cells. This structure is called the primary follicle. A large number of these follicles degenerate during the phase from birth to puberty. At puberty, only 60000 and 80000 primary follicles are left in each ovary. The primary follicles get surrounded by more layers of granulosa cells and a new theca to form secondary follicles
5. (c) Maturation Phase In the first maturation phase, the secondary follicle soon transforms into a tertiary follicle. The primary oocyte within the tertiary follicle grows in size and completes its first meiotic division to form a large haploid secondary oocyte and a tiny first polar body
6. The tertiary follicle changes into a mature follicle-the Graafian follicle which ruptures to release the secondary oocyte (ovum) from the ovary by a process called ovulation. The second maturation phase occurs after fertilization when the meiotic division of the secondary oocyte is complete. This second meiotic division results in the formation of a second polar body and a haploid ovum (ootid)

Answer: (b) Testes

Explanation:
1. Sertoli’s cells are found in human testes, also called nurse cells. These are supportive nutritive cells and secrete a polypeptide hormone called inhibin and a steroid oestradiol which interferes with spermatogenic activity and kinetics of sperm production.

Answer: (c) Fructose, prostaglandin, clotting protein

Explanation:
1. Fructose, prostaglandin, clotting factor
2. Seminal vesicles are present at the base of bladder and joins to the ejaculatory duct. They produces alkaline secretion, which forms 60% of the semen. Their secretion contains, fructose, prostaglandin and clotting factor

Answer: (c) Placenta

Explanation:
1. Chorionic villi and uterine tissue become inter-digitated with each other and jointly form placenta

Answer: (a) Trophoblast outer and somatopleuronic inside

Explanation:
1. Chorion is made up of trophoblast outer and somato pleutronic inside
2. Extraembryonic or Foetal Membranes
3. The growing embryo/foetus develops four membranes called the extraembryoic or foetal membranes. These include chorion, aminion, allantois and yolk sac
4. (i) Chorion It is made up of trophoblast outside and somatopleuric extraembryonic mesoderm inside. It completely surrounds the embryo and protects it. It also takes part in the formation of placenta
5. (ii) Amnion It is composed of trophoblast inside and somatopleuric extraembryonic mesoderm outside. The space between the embryo and the amnion is called the amniotic cavity, which is filled with a clear, watery fluid secreted by both the embryo and the membrane. The amniotic fluid prevents dessication of the embryo and acts as a protective cushion that absorbs shocks
6. (iii) Allantois The allantois is composed of endoderm inside and splanchnopleuric extraembryoic mesoderm outside. It is a sac like structure, which arises from the gut of the embryo near the yolk sac. In human the allantois is small and non-functional except for furnishing blood vessels to the placenta
7. (iv) Yolk Sac The primary yolk sac consists of endoderm inside and splanchnopleuric extraembryoic mesoderm outside. The yolk sac is non-functional in human beings except that it functions as the site of early blood cell formation