Human Reproduction

NEET Biology · 134 questions · Page 9 of 14 · Click an option or "Show Solution" to reveal answer

Q81

Which one of the following is not the function of placenta? It :

A secretes estrogen

B facilitates removal of carbon dioxide and waste material from embryo.

C secretes oxytocin during parturition

D facilitates supply of oxygen and nutrients to embyo

Correct Answer

Option C

Solution

(c) Function of placenta - The placenta facilitate the supply of oxygen and nutrients to the embryo and also removal of carbon dioxide and excretory/waste materials produced by the embryo.

The placenta is connected to the embryo through an umbilical cord which helps in the transport of substances to and from the embryo.

Placenta also acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, progesterone etc.

The umbilical cord is mostly made up of connective tissue known as Wharton's Jelly and has relatively few cells.

The cord has one large umbilical vein and two umbilical arteries.

These vessels transport blood to and from the placenta, where exchange between the mother and fetus takes place.

Q82

Which of these is not an important component of initiation of parturition in humans?

A Synthesis of prostaglandins

B Release of oxytocin

C Release of prolactin

D Increase in estrogen and progesterone ratio

Correct Answer

Option C

Solution

Prolactin is responsible for milk synthesis in mammary glands.

When the levels of estrogen and progesterone become low at parturition, then anterior pituitary activates to release prolactin.

Prostaglandins are synthesized within the human fetal membranes such as amnion, chorion and deciduas.

It plays an important role in ripening of the cervix, change membrane structure and also facilitates the contraction of myometrium.

Q83

Hormones secreted by the placenta to maintain pregnancy are

A hCG, hPL, progestogens, prolactin

B hCG, hPL, estrogens, relaxin, oxytocin

C hCG, progestogens, estrogens, glucocorticoids

D hCG, hPL, progestogens, estrogens

Correct Answer

Option D

Solution

(d) The placenta is an endocrine gland that is only present during pregnancy.

It relases hCG, hPL, progestogens, estrogens, etc.

Human chorionic gonadotropic hormone (hCG) stimulates the corpus luteum during pregnancy to release estrogen and progesterone.

Human placental lactogen (hPL) is involved in growth of body of mother and breast.

Progesterone maintains pregnancy.

Q84

The amnion of mammalian embryo is derived from

A ectoderm and mesoderm

B endoderm and mesoderm

C ectoderm and endoderm

D mesoderm and trophoblast

Correct Answer

Option A

Solution

(a) The extraembryonic membranes are amnion, chorion, allantois and yolk sac.

Amnion is derived from mesoderm on the outer side and ectoderm on the inner side.

Chorion is formed from trophoectoderm and mesoderm, whereas allantois and yolk sac membrane have mesoderm on outerside and endoderm in inner side.

Q85

Which of the following hormones is responsible for both the milk ejection reflex and the foetal ejection reflex?

A Relaxin

B Oestrogen

C Prolactin

D Oxytocin

Correct Answer

Option D

Solution

(d) Foetal ejection reflex triggers release of oxytocin from the maternal anterior pituitary gland.

Oxytocin acts on the uterine muscles and causes stronger uterine contractions.

Milk ejection reflex is caused by combined neurogenic and hormonal reflexes that involve release of oxytocin from posterior pituitary gland.

Relaxin, secreted by the ovary and placenta, causes the cervix to dilate and prepares the uterus for the action of oxytocin during labour.

Oestrogen, secreted from ovary, is responsible for the development and regulation of the female reproductive system and secondary sex characteristics.

Prolactin, secreted from anterior pituitary, stimulates breast development and milk production in women.

Q86

Match the following columns and select the correct option.

$ \begin{array}{|c|c|c|c|} \hline & \text { Column-I } & & \text { Column-II } \\ \hline \text {

A } & \text { (i) } & \text { (iv) } & \text { (ii) } & \text { (iii) } \\ \text {

B } & \text { (iii) } & \text { (ii) } & \text { (iv) } & \text { (i) } \\ \text {

C } & \text { (ii) } & \text { (iii) } & \text { (iv) } & \text { (i) } \\ \text {

D } & \text { (iv) } & \text { (iii) } & \text { (i) } & \text { (ii) } \\ & & & & \end{array} $

Correct Answer

Option C

Solution

Zona pellucida is a primary egg membrane secreted by the secondary oocyte.

The secretions of bulbourethral glands help in lubrication of the penis Leydig cells synthesise and secrete testicular hormones called androgens.

Q87

Seminal plasma in human males is rich in :

A fructose and calcium

B glucose and calcium

C DNA and testosterone

D ribose and potassium

Correct Answer

Option A

Solution

(a) Seminal plasma in human males are rich in fructose, calcium and certain enzymes.

They provide a medium for transport of sperms, nourishes and activates sperms.

Q88

Sertoli cells are found in

A ovaries and secrete progesterone

B adrenal cortex and secrete adrenaline

C seminiferous tubules and provide nutrition to germ cells

D pancreas and secrete cholecystokinin

Correct Answer

Option C

Solution

They anchor and provide nutrition to the developing germ cells especially the spermatids.

Vasa efferentia helps in the transportation of sperms from rete testis to the epididymis (a tube that connects a testicle to a vas deferens) by contraction of smooth muscle.

It also plays an essential role in the reabsorption of luminal fluid, which leads to the increase of the concentration of sperm as they enter the epididymis.

Q89

Which one of the following statements about morula in humans is correct?

A It has almost equal quantity of cytoplasm as an uncleaved zygote but much more DNA

B It has far less cytoplasm as well as less DNA than in an uncleaved zygote

C It has more or less equal quantity of cytoplasm and DNA as in uncleaved zygote

D It has more cytoplasm and more DNA than an uncleaved zygote

Correct Answer

Option A

Solution

(a) Morula has equal cytoplasm but much more DNA than the uncleaved zygote.

Q90

Withdrawal of which of the following hormones is the immediate cause of menstruation?

A FSH

B FSH-RH

C Progesterone

D Estrogen

Correct Answer

Option C

Solution

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