NEET Biology Human Reproduction MCQs Set 21

Answer: (b) Abdominal cavity

Explanation:
1. During early and middle foetal life the testis are located in the abdominal cavity. They come to the scrotal sac in the late foetal development Cryptorchidism is the condition in which testis do not descent into the scrotum

Answer: (d) ICSH

Explanation:
1. In the male, ICSH stimulates the interstitial cells or Leydig’s cells in testis to develop and secrete large amount of testosterone.

Answer: (c) Mesoderm – Skeleton

Explanation:
1. Notochord, circulatory system, organs of urogenital system (including ureter, kidney, gonads, reproductive ductes); skeletal muscle, bone, cartilage of skeleton (except skull), dermis, connective tissues, etc are the derivatives of mesoderm.

Answer: (c) Prolactin

Explanation:
1. Prolactin is a protein-gonadotrophic hormone secreted by the vertebrate anterior pituitary gland. In mammals, it promotes secretion of progesterone by the corpus luteum and is involved in milk secretion (lactation).

Answer: (b) Progesterone

Explanation:
1. During luteal phase of menstrual cycle, corpus luteum begins to secrete hormone called progesterone. The latter reaches its peak about 22^nd day after the beinning of cycle. In this phase uterus linning thickens further and becomes secretory. This stages is meant for receiving the fertilized ovum (implantation)

Answer: (c) No fusion

Explanation:
1. Amphimixis is the formation of new individuals through normal process of sexual reproduction (i.e., meiosis and syngamy). Syngamy is the fusion of sperm nucleus with egg nucleus.

Answer: (a) Corona radiate, zonapellucida and vitelline membrane

Explanation:
1. Layers of an ovum from outside to inside are corona radiate, zona pellucida and vitelline membrane.

Answer: (a) Human placental lactogen (\(\mathrm{hPL}\))

Explanation:
1. Endocrine Functions of Placenta Placenta secretes some hormones such as oestrogen, progesterone, human Chorionic Gonadotropin (\(\mathrm{hCG}\)), human Chorionic Somato-mammotropin (\(\mathrm{hCS}\)), Chorionic thyrotrophin, chorionic corticotropin and relaxin. \(\mathrm{hCS}\) was formarly known as human placental lactogen. The hCG stimulates and maintains the corpus luteum to secrete progesterone until the end of pregnancy.
2. The hCS stimulates the growth of the mammary gland during pregnancy. Relaxin facailitates parturition (act of child birth) by softening of the connective tissue of the pubic symphysis

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

Explanation:
1. According to some embryologists, the hypoblast is termed the embryonic endoderm, the first germ layer to be formed. Some workers called epiblast as ectoderm, the second germ layer.

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

Explanation:
1. The forehead of the penis is covered by the skin. Foreskin and prepuce both terms are used for that skin

Answer: (b) Zygote

Explanation:
1. Implantation
2. (i) Zygote divides rapidly by mitotic division. This is called cleavage. As a result 2, 4, 8, 16 daughter cells are produced which are termed as blastomeres
3. (ii) Embryo with 8-16 blastomeres is called a morula
4. (iii) The morula changes into a large mass of cells called blastocyst, which passes further into the uterus
5. (iv) Blastomeres in the blastocyst are arranged into an outer layer called trophoblast and an inner group of cells attached to trophoblast called inner cell mass
6. (v) The trophoblast layer gets attached to the cells of the endometrium and the inner cell mass gives rise to the embryo
7. (vi) The cells of endometrium divide rapidly and cover the blastocyst
8. (vii) So, the blastocyst gets embedded in the endometrium of the uterus. This is called implantation, which leads to pregnancy

Answer: (b) 44

Explanation:
1. Human cell contain 46 chromosomes including 44 autosomes. Primary spermatocyte contain 2\(n\) number of chromosome i.e., the number of autosomes, will be 44.

Answer: (b) \(\mathrm{I→III→V→IV→II}\)

Explanation:
1. In human female reproductive cycle or menstrual cycle during proliferative phase, the anterior lobe of pituitary gland secretes the Follicle Stimulating Hormone (FSH), which stimulates to ovarian follicles to secrete oestrogens. During the second week of reproduction cycle, most of the developing follicle die and usually one follicle continues to mature. Now the Luteinzing Hormone (LH) in blood level increase by pituitary gland. A small surge of FSH also occurs. Now ovulation takes place, which releases immature egg into abdominal cavity. During ovulation, the follicle breaks open and collapses under the continuous influence of Luteinizing Hormone(LH). It begins to enlarge and forms a yellowish strucyure, called corpus luteum or yellow body.

Answer: (a) Progesterone

Explanation:
1. Contraception pills for women contain female sex hormones oestrogen and progesterone.

Answer: (b) Ostrich

Explanation:
1. Largest egg is of ostrich.

Answer: (d) Colostrum

Explanation:
1. Human Placental Lactogen (HPL) causes production of milk in mammary glands, oxytocin initiates milk flow and prolactin regulates milk flow. The first milk produced after child birth is called colostrum and is very nutritious.

Answer: (d) Exponential phase

Explanation:
1. In growth curve, exponential phase or log phase is characterized rapid growth in population, which containues till enough food is available.

Answer: (d) Epididymis

Explanation:
1. The secretion of testosterone by the Leydig’s cells of the testis subseqently causes growth and development of the Wolffian ducts into male accessory sex organs, the epididymis, seminal vesicles and ejaculatory duct.

Answer: (a) Morphallaxis–regeneration of two transversely cut equal pieces of one Hydra into two small Hydras

Explanation:
1. Morphallaxis involves the reconstruction of whole body from small fragment by reorganizing the existing cells, e.g., Regeneration of Hydra from its piece

Answer: (b) 400

Explanation:
1. Starting of menstrual cycle \(=13\) th year of age.
2. Stopping of menstrual cycle = 48 years of age.
3. Duration of menstrual cycle are \(=48-13=35\) yr
4. Total no. of month is 35 years \(=35×12=400\) months
5. One ova is released during one menstrual cycle (one months).
6. So, about 400 ova (follicles) will be produced by a women in its life time

Answer: (b) Progesterone

Explanation:
1. The ruptured follicle of ovary after ovulation gives rise to corpus luteun which is the source for secretion of progesterone. This hormone is responsible for growth and maintenance of foetus. Oestrogen is produced by theca interna cells of Graafian follicles.
2. Male hormone called androgen is produced by interstitial calls of Leydig.

Answer: (d) Sympathetic nerve only

Explanation:
1. The movement of spermatozoa, from the epididymal duct and seminal fluid into the ejaculatory duct to the urethra is under the control of sympathetic nervous system.
2. Ejaculation is the sympathetic response while erection is a parasympathetic response.
3. Sympathetic and parasympathetic both are the part of autonomic nervous system.

Answer: (a) Temperature of testis

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: (b) Human placental lactogen

Explanation:
1. Human placental lactogen stimulates growth and development of breast in preparation for lactation. This hormone is needed before oestrogen and progesterone can have their effects on breasts.

Answer: (a) FSH

Explanation:
1. The end of menstrual cycle is known as menopause. It come at the age of 45 to 50 years. During menopause, the level of FSH (Follicle Stimulating Hormone) rises in urine.