NEET Biology Human Reproduction MCQs Set 20

Answer: (a) GH

Explanation:
1. Menstruation occurs in human, apes and old world monkeys. Menstruation is bleeding from uterus of adult female at intervals of one lunar month. A reduction in oestrogens and progesterone causes menstruation. Gonadotropin releasing hormone secreted by the hypothalamus stimulates the release of FSH and LH. FSH and LH stimulate the ovarian follicles to produce more oestrogens during proliferative phase of menstrual cycle. Growth hormone (GH) has no role in the process of menstrual cycle.

Answer: (a) Reduced

Explanation:
1. In menstrual phase, the production of LH and progesterone decreases.
2. Menstrual cycle

Answer: (c) One X-chromosome

Explanation:
1. The female individual contains two X chromosomes. The eggs are produced by the meiosis, i.e., reduction division. So, the egg contains one X-chromosome, when released from ovary. After fertilization, the diploid phase is restrored.

Answer: (b) Inner cell mass

Explanation:
1. All the three germ layer (ectoderm, endoderm, mesoderm) are originated form inner cell mass

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

Explanation:
1. Cone of reception. The secondary oocyte forms a projection termed as the cone of reception or fertilization cone, which receives the sperm

Answer: (b) Gil slits

Explanation:
1. All the chordates (including humans) at some stages of their life cycle, contain a series of paired lateral gills clefts or gill slits. These are finger like, hollow pouches that grow out from pharyngeal wall and meet with corresponding inpocketing of body wall. In lower chordates, gill clefts serve as respiratory organs but in higher chordates, these are present only during embryonic development.

Answer: (d) Yolk sac

Explanation:
1. Yolk sac.
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

Answer: (a) A-middle piece, B-tail, C-acrosome

Explanation:
1. Structure of a sperm (spermatozoa) It consists of four parts i.e., Head, Neck, Middle piece and tail, enveloped by a plasma membrane.
2. HeadIt 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.
3. 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.
4. Middle piece It contains a number of mitochondria that provide energy for the movement of the tail that facilitate sperm motility essential or fertilization.
5. Tail It consists of axial filaments surrounded by the plasma membrane. It helps the sperms to swim in a fluid medium

Answer: (b) Corpus luteum

Explanation:
1. Corpus luteum secretes the hormone progesterone, which prepares and maintains the uterus during pregnancy.

Answer: (c) mitochondria and 9+2 arrangement of microtubules

Explanation:
1. A cross section at the midpoint of the middle piece of a sperm will show mitochondria and 9+2 arrangement of microtubules.

Answer: (b) Bladder

Explanation:
1. 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) Ovulatory phase

Explanation:
1. LH and FSH both are present in follicular phase but LH’s high concentration is seen in ovulatory phase.
2. Menstrual cycle

Answer: (a) Primary oocyte in the Graafian follicle

Explanation:
1. During growth phase of oogenesis, an egg nest forms ovarian follicle (Graafin follicle), one central oogonium grows and functions as primary oocyte. The others from the covering follicular cells. The later provide nourishment to primary oocyte. Yolk is deposited in this state. This phenomenon is called vitellogenesis.

Answer: (b) Vasa deferentia

Explanation:
1. Vasa deferentia emerges from the cauda epididymis on each side and leaves the scrotal sac and enters the abdominal cavity through inguinal canal. It is lined by many stereocilia to transport the sperms from testis to the outside through urethra

Answer: (c) Seminiferous tubules and Leydig cells

Explanation:
1. Two major entities of testes are seminiferous tubules and Leydig cells (or interstitial cells). Sertoli cells and spermatozoa are contained in seminiferous tubules only. Rest of the portion of testis is covered by connective tissue

Answer: (a) LH

Explanation:
1. Ovulation is release of ovum LH secreted by anterior pituitary gland is responsible for ovulation.

Answer: (c) Trophoblast and mesoderm

Explanation:
1. Placenta is an organic connection between the foetus and uterine wall for physiological exchange between foetus and mothers blood. The placenta develops at the point of implantation. Extraembryonic membrane, i.e., amnion, allantois, chorion and yolk sac are formed from trophoblast (the ring of cells surrounding the inner cell mass in a developing pro-embryo). Chorion is formed of ectoderm externally and mesoderm inside. Along with allantois, it participates in formation of placenta.

Answer: (d) Chorion

Explanation:
1. The foetal part of the placenta in human is formed by the chorionic villi, which lie in the maternal blood pool, formed by the erosion of uterine endometrium and endothelial wall of uterine blood vessels to form the haemochorial placenta.

Answer: (b) Labia majora

Explanation:
1. Labia majora,these are two large fleshy folds of skin which form the boundary of vulva. They are partly covered by pubic hair and contain large number of sebaceous (oil) glands. The labia majora are considered homologous to the scrotum of the male

Answer: (b) Prolactin

Explanation:
1. Prolactin is secreted by anterior pituitary gland, which stimulates mammary gland development during pregnancy and lactation after child birth.

Answer: (a) Fructose and calcium

Explanation:
1. Seminal plasma is composed of the fluid and sperms from the vas deferens (about10% of the total), fluid from the seminal vesicles (almost 60%), fluid from the prostate gland (about 30%) and small amount of mucous gland secretions, especially the bulbourethral glands secretions. It contains calcium, citrate ion, phosphate ion a clotting enzyme, profibrinolysin, fructose, citrate, inositol, prostaglandins, several proteins, etc.

Answer: (a) Mesoderm

Explanation:
1. Fate of three germ layers
2. Mesoderm Dermis of skin, circulatory system, muscles, bones (except facial)
3. Endoderm Lining of \(\mathrm{Gl}\) tract, lining of lungs, kidney ducts and bladder, thymus, thyroid tonsils
4. Ectoderm Epidermis of skin, tooth enamel, lens and cornea of the eye outer ear Brain and spinal cord, facial bones skeletal muscles in the head

Answer: (c) A-epididymis; B-posterior

Explanation:
1. A-epididymis; B-Posterior

Answer: (a) Acrosomal reaction

Explanation:
1. Hyaluronidase enzyme assists in acrosomal reaction. This enzyme acts on the ground substances of follicle cells

Answer: (c) A-sympathetic, B-parasympathetic

Explanation:
1. Ejaculation is the sympathetic response while erection is a parasympathetic response.
2. Sympathetic and parasympathetic both are the part of autonomic nervous system.