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Questions:

Case Study Questions

15 x 4 = 60

Read the following and answer any four questions from (i) to (v) given below:
The first menstruation is called menarche, that usually occurs between 12 and 15 years. In human females, menstruation is repeated at an average interval of about 28129 days and is called menstrual cycle. It is regulated by certain hormones, as pituitary gland is stimulated by releasing factors produced in the hypothalamus. The hormones produced by pituitary gland influence the ovaries. The hormones secreted by the ovaries affect the walls of the uterus.
(i) The breakdown of endometrium is characteristic of

(a) proliferative phase

(b) luteal phase

(c) ovulatory phase

(d) menstrual phase

(ii) Which days of the menstrual cycle marks the proliferative phase?

(a) 1-5

(b) 15-28

(c) 6-13

(d) 10-14

(iii) Which of the following occurs during secretory phase?

(a) Empty Graafian follicle changes into corpus luteum.

(b) Primary follicle changes' into Graafian follicle.

(c) Endometrium rebuilds and estrogen secretion increases

(d) LH surge inducing release of an ovum.

(iv) Identify the hormones that attain peak level during ovulatory phase

(a) FSH

(b) Progesterone

(c) LH

(d) Both (a) and (c)

(v) Withdrawal of which hormone causes degeneration of corpus luteum?

(a) FSH

(b) LH

(c) Progesterone

(d) Estrogen

Read the following and answer any four questions from (i) to (v) given below:
Oogenesis is the process of formation of ovum in ovaries. It consists of three phases : multiplication, growth and maturation. Oogenesis is controlled by hormones GnRH, LH, FSH. GnRH secreted by the hypothalamus stimulates the anterior lobe of pituitary gland to secrete LH and FSH.
(i) What is the function of hormone FSH?

(a) It inhibits the formation of estrogen

(b) It induces the release of secondary oocyte

(c) It stimulates the growth of Graafian follicles

(d) It causes ovulation.

(ii) Which hormone induces the rupture of the mature Graafian follicle?

(a) Follicle stimulating hormone

(b) Gonadotropin releasing hormone

(c) Progesterone

(d) Luteinising hormone

(iii) Which cell division is involved in the formation of secondary oocyte?

(a) Mitosis

(b) Meiosis I

(c) Amitosis

(d) Meiosis II

(iv) Identify the function(s) of LH.
(A) Release of secondary oocyte from Graafian follicle.
(B) Stimulates corpus luteum to secrete progesterone.
(C) Stimulates estrogen formation.
(D) Promotes development of egg to form secondary oocyte.

(a) (A) and (B) only

(b) (B) and (C) only

(c) (A), (C) and (D) only

(d) (B) only

(v) Assertion: The increase in progesterone level exerts positive feedback on GnRH
Reason: The rising level of progesterone stimulate production of FSH and LH.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false.

Read the following and answer any four questions from (i) to (v) given below:
Human male reproductive system comprises of a pair of testes, primary sex organs associated with formation of gametes and production of sex hormone. Study the given figure of human male reproductive system and answer the following questions.

(i) Which of the following is correct for labelled part P?

(a) P is rete testis which transports sperms to outside.

(b) P is epididymis which secretes fluid that nourish the sperms

(c) P is epididymis that carry sperms and secretion of seminal vesicles

(d) P is rete testis which lies along inner side of each testis and stores the sperms

(ii) Identify the correctly matched pair.

(a) Q - Vasa efferentia

(b) R - Ejaculatory duct

(c) S - Seminal vesicle

(d) T - Cowper's gland

(iii) Which statement is incorrect for Q?

(a) It carries spermatozoa from epididymis to ejaculatory duct

(b) Q are only 2 in number.

(c) It arises from rete testis.

(d) It constitutes male sex accessory duct

(iv) Which structure passes through the prostate gland and carries sperms and secretion of seminal vesicle?

(a) P

(b) T

(c) S

(d) R

(v) Assertion: Mucus present in secretion of bulbourethral gland decreases the number of sperms damaged during ejaculation
Reason: Mucus lubricates the end of penis and lining of the urethra.
(a) Both assertion and reason are true and reason is the correct explanation of assertion.
(b) Both assertion and reason are true but reason is not the correct explanation of assertion.
(c) Assertion is true but reason is false.
(d) Both assertion and reason are false .

Three of the steps in the neuro-endocrine mechanism of parturition are mentioned below. Write the other missing steps.
(a) Signals for parturition originate from the fullydeveloped foetus and placenta.
(b) _________________.
(c) _________________.
(d) Oxytocin causes stronger uterine contractions, which stimulate further secretion of oxytocin.
(e) __________________.
(f) ________________.

(a) Name the human embryonic stage shown above.
(b) Identify 'a' and 'b' in it.
(c) Where are stem cells located in it?
(d) Mention the role of 'b'.

(a) Identify the human embryonic stages, A and B given.
(b) Write two differences between A and B.

Study the flow chart given below and answer the questions that follow:

(a) Name the hormone(s) (in full form) involved in each of the stages,
(b) Specify the structure in the ovary that is the source of the hormone at stage

(a) Identify the pituitary hormones 'X' and 'Y' shown in the graph.
(b) Mention two functions each of X and Y in human females.

Read the graph given above and answer the following questions:
(a) Identify the ovarian hormones X and Y and name their respective sources in the ovary.
(b) Why does the hormone X peak before the hormone Y?

10.

The events in a menstrual cycle are represented above. Answer the following questions based on that.
(a) Why is the phase between 5^th and 15^th day of menstrual cycle, called
(i) proliferative phase?
(ii) follicular phase?
(b) Mention the ovarian events during the luteal phase.

11.

(A) In the diagrammatic sectional view of a human ovary, identify the following:
(i) Corpus luteum
(ii) Antrum
(iii) Secondary oocyte
(iv) Primary follicle
(B) Name the hormone that
(i) influences the formation of corpus luteum.
(ii) is secreted by corpus luteum.

12.

With reference to the above schematic diagram of (a) Spermatogenesis and (b) Oogenesis, answer the following questions.
(a) About 300 million spermatozoa may be present in a human male ejaculate at one time. Calculate how many primary spermatocytes will be involved to produce this number of spermatozoa .
(b) How many spermatids will be formed?
(c) How many chromatids are found during Oogenesis in
(i) Primary oocyte and
(ii) First polar body in a human female?

13.

Study the following flow chart and answer the questions that follow:

14.

A Human Spermatozoan
A diagrammatic sketch of a human sperm is given. Identify the parts labelled A, Band C and mention their respective functions.

15.

A diagrammatic sketch of the human male reproductive system is given above.
(a) Identify and name the three glands associated with the human male reproductive system. What is the term given to their secretions?
(b) Name the primary sex organ and the pouch in which it is located in human beings.

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Answers Key:

Case Study Questions

15 x 4 = 60

(i) (d): During menstrual phase, the endometrium breaks down and menstruation begins.
(ii) (c) : Proliferative phase extends for about 10-12 days usually from day 6th to 13th in a 28 day cycle
(iii) (a)
(iv) (d) : During ovulatory phase, both LH and FSH attain a peak level
(v) (b)

(i) (c) : FSH stimulates the growth of Graafian follicles, development of egg oocyte within the follicles to complete the meiosis I to form secondary oocyte. It also stimulates the formation of estrogen.
(ii) (d) : LH induces rupture of mature Graafian follicle and thereby the release of secondary oocyte.
(iii) (c) : FSH stimulates the growth of Graafian follicles, development of egg oocyte within the follicles to complete the meiosis I to form secondary oocyte. It also stimulates the formation of estrogen.
(iv) (a)
(v) (d) : The rising level of progesterone inhibits the release of GnRH, which in turn inhibits production of FSH, LH and progesterone.

(i) (b) : P is an epididymis that stores the sperms and secretes a fluid which is considered to nourish the sperms
(ii) (b) : Q - Vas deferens, R - Ejaculatory duct S - Bulbourethral gland, T - Seminal vesicle
(iii) (c) :Q (vas deferens) arises from cauda epididymis
(iv) (d)
(v) (a)

(b) They induce mild uterine contractions, called foetal ejection reflex.
(c) This triggers the release of oxytocin from the maternal pituitary.
(e) The stimulatory reflex between the uterine contractions and oxytocin secretion continues and results in stronger and stronger uterine contractions.
(f) This leads to expulsion of the foetus through the birth canal, i.e., parturition.

(a) It is a blastocyst.
(b) 'a' is inner cell mass.
'b' is trophoblast.
(c) Stem cells are present in the inner cell mass.
(d) Role of Trophoblast.
(i) It becomes attached to the endometrium for implantation.
(ii) The chorionic villi appearing on it form the foetal part of placenta.

(a) A is a morula
B is a blastocyst.

Morula	Blastocyst
It is a solid sphere of8-16 blastomeres formed by cleavage of zygote	It is a hollow sphere of cells, formed by the rearrangement of blastomeres.
Zona pellucida is intact	Zona pellucida disintegrates with the enlargement of blastocoel.

(i) 1. Gonadotropin-releasing hormone (GnRH)
2. Follicle-stimulating hormone (FSH) and Luteinising hormone (LH)
3. Progesterone.
(b) Corpus luteum secretes progesterone.

(a) X is luteinizing hormone (LH).
Y is follicle-stimulating hormone (FSH).
(b) Functions of X
(i) The LH-surge causes rupture of Graafian follicle and release of ovum, in the process, called ovulation.
(ii) It influences the formation of corpus luteum from the remaining parts of the Graafian follicle and secretion of progesterone from it.
Functions of Y
(i) It stimulates the growth of a primary follicleinto a Graafian follicle and thus, influences oogenesis.
(ii) It stimulates the cells of the developing follicle to secrete estrogens.

(a) X is hormone estrogen.
(i) It is secreted by the cells of the developing follicle.
Y is hormone progesterone.
(ii) It is secreted by corpus luteum.
(b) (i) X is secreted by the cells of the follicle during follicular phase before ovulation; after the rupture of Graafian follicle, there is no secretion of estrogen.
(ii) Y is secreted by corpus luteum that is formed after ovulation in the luteal phase; hence X peaks before Y.

10.

(a) (i) It is called proliferative phase because the endometrium of the uterus is regenerated through prol iferation of its cells.
(ii) It is called follicular phase as the primary follicle in the ovary grows to become a fully mature Graafian follicle under the influence of follicle-stimulating hormone.
(b) (i) Corpus luteum is formed from the remaining parts of the ruptured Graafian follicle.
(ii) Corpus luteum secretes large amounts of progesterone.

11.

(A) (i) - (d), (ii) - (b), (iii) - (c), (iv) - (e)
(b) (i) - Luteinising hormone
(ii) - Progesterone

12.

(i) 75 million
(b) 300 million
c) (i) 92 chromatids
(ii) 46 chromatids

13.

(a) 1. Gonadotropin-releasing hormone (GnRH)
2. Follicle-stimulating hormone (FSH) Luteinising hormone (LH)
3. Testosterone
(b) (i) Leydig cells secrete testosterone.
(ii) Sertoli cells secrete some factors necessary for spermiogenesis.

14.

A. Acrosome
(i) The secretions.enzymes of acrosome dissolve the egg envelopes and help the sperm enter the cytoplasm of the ovum.
B. Mitochondria
(i) The mitochondria in the middle piece provide energy for the sperm motility in the female reproductive tract towards ovum.
C. Tail
(i) It facilitates the movement of sperm towards the ovum for fertilisation.

15.

(a) A. Seminal vesicle
B. Prostate gland
C. Bulbourethral gland
(i) Their secretions constitute seminal plasma.
(b) Testis is the primary sex organ and it is located in the scrotum.