NEET Biology Human Reproduction MCQs Set 08

Answer: (a) Umbilical cord

Explanation:
1. Umbilical cordconnects the foetus to placenta of mother. It mainly consists of allantoic mesoderm and blood vessels (umbilical artery and veins).

Answer: (a) Stem cell

Explanation:
1. Stem cells are the specialized cell which can transform or differentiated into any kind of cells

Answer: (d) Human sperm

Explanation:
1. Acrosome is a part of human sperm.

Answer: (b) Athenospermia

Explanation:
1. Athenospermia is the condition where the motility of sperms is highly reduced.
2. The condition of presence of completely non-motil sperms in human semen is known as necrospermia.
3. The condition when less number of sperms is found in semen is termed as oligospermia. The penetration of many sperms into an ovum simultaneously is termed as polyspermy.

Answer: (d) Paedogenesis

Explanation:
1. Paedogenesis literally means ‘reproduction by the child’. Infact, it is reproduction by immature or larval animals caused by acceleration of mutation. Paedogenesis occurs in very small flies such as Miastor and in Oligarces.

Answer: (a) At birth

Explanation:
1. No more oogonia are formed and added after birth. Oogonia (egg mother cells) divide by mitosis forming primary oocyte. Each primary oocyte then gets surrounded by a layer of granulosa cell called primary follicle. A larger number of these follicles degenerate during the phase from birth to puberty. Therefore, at maturity only 60,000-80,000 primary follicles are left in each ovary

Answer: (a) 2-2.5 below body temperature

Explanation:
1. Scrotum maintains the temperature of testis, which is 2-2.5\(°C\) below the body temperature. In winter they reduces their surface area for preventing heat loss, so that temperature remains 34.5-35\(℃\). In summer it increase their surface area for cooling, so that the temperature remains 34.5-35\(℃\)

Answer: (d) The transfer of sperms by male in to the genital tract of female

Explanation:
1. Transfer of sperms by male in genital tract
2. Gametes. The major reproductive events in human beings are as follows
3. (i) Gametogenesis It is the formation of gametes. It includes spermatogenesis (formation of sperms) and oogenesis (formation of ova/eggs)
4. (ii) Insemination It is the transfer of sperms by the male into the genital tract of the female
5. (iii) Fertilization Fusion of male and female gametes to form zygote is called fertilization
6. (iv) Cleavage It is rapid mitotic divisions of the zygote which convert the single celled zygote into a multicellular structure called blastocyst (blastula)
7. (v) Implantation It is the attachment of blastocyst to the uterine wall
8. (vi) Placentation It involves the formation of placenta which is the intimate connection between the foetus and uterine wall of the mother to exchange the materials
9. (vii) Gastrulation It is the process by which blastocyst is changed into gastrula with three primary germ layers
10. (viii) Organogenesis It is the formation of specific tissue, organs and organ systems from three primary germ layers
11. (ix) Parturition (child birth) it involves expelling of the baby from the mother’s womb (uterus)

Answer: (b) Fallopian tube

Explanation:
1. In rabbit, man and other placental mammals, fertilization takes place in the upper part of the fallopian tube (ampulla).

Answer: (b) Endometrium regenerates - 5 -14 days

Explanation:
1. The growth of superficial and middle layer of endometrium occurs from the 5^th to 14^th day of the cycle under the influence of oestrogen.

Answer: (a) Oogonia

Explanation:
1. Female gamete mother cells are called oogonia.
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: (a) Parthenogenesis

Explanation:
1. Parthenogenesis is the development of an embryo from an unfertilized egg or if a spermatozoan does penetrate the egg, there is no union of male and female pronuclei.

Answer: (d) Some blastomeres and blastocoel degenerate

Explanation:
1. Gasrtulation is characterized by the presence of archenteron, three germinal layers (ectoderm, mesoderm, and endoderm) and morphogenetic movements.

Answer: (a) Fertilization\(→\) zygote \(→\) cleavage \(→\) morula \(→\) blastula \(→\) gastrula

Explanation:
1. Correct sequence in development is fertilisation (union of male
2. of male and female gamete)
3. \(↓\)
4. Zygote (syngany or amphioxis) leads to the zygote)
5. \(↓\)
6. Cleavage (series of rapid mitotic division of the zygote)
7. \(↓\)
8. Morula (8-16 blastomere structure called morula having similar types of cells)
9. \(↓\)
10. Blastula (more than 16 blastomere (approx.-64) it is hollow structure
11. With blastocoel cavity in center)
12. \(↓\)
13. Gastrula (Transformation of the blastocyst in the gastrula with primary germ layer by rearrangement a cell called gastrulation and structure is called gastrula)

Answer: (b) Homologous to penis

Explanation:
1. Clitoris is considered as rudimentary organ in female external genitalia and considered as homologous to penis

Answer: (a) Lubricate the penis

Explanation:
1. Bulbourethral gland secretes mucus, which lubricate penis during intercourse. This reduces the friction during the process. Bulbourethral gland is also called Cowper’s gland

Answer: (d) Both (a) and (b)

Explanation:
1. There are two types of polar bodies found in oogenesis in meiosis-I the first polar body is formed and in meiosis-II the 2nd type of polar body is formed. Meiosis-I takes place before birth and meiosis-II after birth of female

Answer: (a) Archenteron

Explanation:
1. Gastrulation is the process by which a blastula is converted into gastrula. By the end of gastrulation three layered embryo is formed, which is enclosing an archenteron.

Answer: (c) Secondary spermatocyte

Explanation:
1. Secondary spermatocytes. The first stage in spermatogenesis in which the chromosome number becomes half
2. Spermatogenesis Formation of spermatozoa from spermatogonia
3. Spermatogenesis has four phase
4. (i)Multiplication Phase Male germ cells (spermatogonia) present on the inside wall of seminiferous tubules multiply by mitotic division and increase their number.
5. (ii)Growth Phase One spermatogonia stop dividing and increase its size called primary spermatocytes, which is diploid.
6. (iii)Multiplicative Phase Primary spermatocytes divide by meiosis to give four haploid spermatids.
7. (iii)Differanation Phase Changing of spermatids to spermatozoa by the process called spermatogenesis. Releasing of sperm from seminiferous tubules called spermiation

Answer: (a) Fusion of male and female gametes

Explanation:
1. Fusion of male and female gametes is called fertilization. It can be external (outside the female genital tract) like frog, fishes or internal (inside the female genital tract) like mammals, birds, etc.

Answer: (a) 250

Explanation:
1. There are about 250 compartments in human testis called testicular lobules

Answer: (d) Both (b) and (c)

Explanation:
1. All fishes are oviparous, but whale is viviparous, i.e., it gives birth to young ones and it also feeds its young ones. Among flying creatures, bat is viviparous. Whale and bat both are mammals.

Answer: (b) Kidney of frog

Explanation:
1. Bidder’s canal is a part of urinogenital system of male frog. It is the longitudinal canal of kidney into which the collecting canals open and put the sperms received. Posteriorly, it continues into the ureter.

Answer: (b) 15-28 days

Explanation:
1. Luteal phase last for 15-28 days
2. Menstrual cycle

Answer: (c) Cleavage is repeated mitotic division of zygote

Explanation:
1. Fertilized zygote is divided by special type of mitotic divisions, known as cleavage. Cleavage increases the number of cells.