CBSE Class 12 Biology Human Reproduction Worksheet Set G

              Very Short Answer

Q1)       What are androgens?

Q2)       What is scrotum?

Q3)       Define urethral meatus?

Q4)       How can we maintain the low temperature of the testes?

Q5)       What are testicular lobules?

              Short Answer

Q6)       Define parturition and lactation?

Q7)       What do you mean by the term implantation in human reproduction?

Q8)       What do you understand by the male gems cells and sertoli cells?

Q9)       Define spermiogenesis?

Q10)     What do you meant by fallopian tubes?

              Long Answer

Q11)     Write short note on gametogenesis?

Q12)     Write short note on fertilization in human reproduction?

Q13)     State the difference between male reproductive system and female reproductive system?

Q14)     Write short note on embryonic development?

Q15)     Explain about menstrual cycle?

 Long Answer Questions

Questions. When and where do chorionic villi appear in humans? State their function.
Answer. Chorionic villi appear after implantation on the trophoblast.
It becomes interdigitated with uterine tissue to form the placenta and increases the surface area for exchange of materials between the mother and the embryo.

Questions. (i) How is placenta formed in the human female?
(ii) Name any two hormones which are secreted by it and are also present in a non-pregnant woman.
Answer. (i) The chorionic villi and uterine tissue become interdigitated with each other and jointly form a structural and functional unit called placenta.
(ii) Estrogen and progestogens.

Questions. 

Read the graph given above showing the levels of ovarian hormones during menstruation and correlate the uterine events that take place according to the hormonal levels on:
(i) 6–15 days
(ii) 16–25 days
(iii) 26–28 days (if the ovum is not fertilised) 
Ans. (i) Regeneration of endometrium.
(ii) Uterus gets highly vascularised, ready for embryo implantation.
(iii) Disintegration of the endometrium leading to menstruation.

Questions. Study the graph given below and answer the questions that follow:
(a) Name the hormones ‘X’ and ‘Y’.
(b) Explain the ovarian events (i), (ii) and (iii) under the influence of hormones ‘X’ and ‘Y’.

Answer. (a) Hormone ‘X’: Luteinising hormone.
Hormone ‘Y’: Follicle stimulating hormone.
(b) (i) FSH is secreted by the anterior pituitary which stimulates the ovarian follicle to secrete estrogen, which in turn stimulates the proliferation of the endometrium of the uterine wall.
(ii) Both LH and FSH attain a peak level in the middle of cycle (about 14th day). Rapid secretion of LH leading to its maximum level during the mid-cycle called LH surge induces rupture of Graafian follicle and thereby the release of ovum (ovulation).
(iii) The remaining cells of ovarian follicles are stimulated by the LH to transform into corpus luteum. The corpus luteum secretes large amount of progesterone which is essential for maintenance of the endometrium.

Questions. Explain the hormonal control of spermatogenesis in humans.
Answer. Refer to Basic concept 3 (i) Hormonal control of spermatogenesis.

Questions. (i) Draw a sectional view of human ovary and label 
Answer: (a) Primary follicle (b) Graafian follicle (c) Corpus luteum

(ii) Mention the effect of pituitary hormones on the parts labelled.
Answer. (i)

(ii) The pituitary hormones FSH and LH effect the growth and development of primary follicle, Graafian follicle and corpus luteum.

Questions. (a) Write the specific location and the functions of the following cells in human males:
(i) Leydig cells (ii) Sertoli cells
(iii) Primary spermatocyte.
(ii) Explain the role of any two accessory glands in human male reproductive system.
Answer. (a) (Table 106)

Questions. (a) Where does spermatogenesis occur in human testes? Describe the process of spermatogenesis upto the formation of spermatozoa.
(b) Trace the path of spermatozoa from the testes upto the ejaculatory duct only.
OR
Schematically represent and explain the events of spermatogenesis in humans.
Answer. (a) Spermatogenesis occur in seminiferous tubules.

(b) The path of spermatozoa is as follows:
Seminiferous tubules Rete testis Vasa efferentia Epididymis
Vas deferens Ejaculatory duct
OR

Questions. What role does pituitary gonadotropins play during follicular and ovulatory phases of menstrual cycle and also explain the shift in steroidal secretions. 
Answer. Menstrual cycle is regulated by hypothalamus through the pituitary gland. At the end of menstrual phase, the pituitary FSH gradually increases resulting in follicular development within the ovaries. As the follicles mature, estrogen secretion increases resulting in a surge in FSH and  LH. The surge of LH is responsible for ovulation and formation of corpus luteum that secretes progesterone which helps in maintaining the endometrium for implantation.

Questions. Give the term/reason: 
(a) Mechanism responsible for parturition.
(b) Role of oxytocin during expulsion of the baby out of uterus
(c) Why does zona pellucida layer block the entry of additional sperms?
(d) Sperm cannot reach ovum without seminal plasma.
(e) All copulations do not lead to fertilisation and pregnancy.
Answer. (a) The complete neuro-endocrine mechanism.
(b) Oxytocin acts on uterine muscle for stronger contraction.
(c) To ensure the fusion of only one sperm with the ovum nucleus.
(d) Seminal plasma is a liquid medium which helps the sperm to move and nourishes it.
(e) All copulations do not lead to fertilization and pregnancy because fertilisation can only occur of the ovum and sperms are transported simultaneously to the ampullary-isthmic junction.

Questions. (a) When and where does spermatogenesis occur in a human male?
(b) Draw a diagram of a mature human male gamete. Label the following parts: Acrosome, nucleus, middle piece and tail. 
(c) Mention the functions of acrosome and middle piece.
Answer. (a) Spermatogenesis occurs at puberty in testes.
(c) Acrosome: Acrosome contains hydrolytic enzymes that help in dissolving membranes of the ovum for sperm entry, ensuring fertilisation.
Middle piece: It contains a number of mitochondria that provide energy for the movement of the tail and thus provides motility to sperm.

Questions. (i) Draw a diagrammatic sectional view of the female reproductive system of human and label the parts
(a) where the secondary oocytes develop
(b) which helps in collection of ovum after ovulation
(c) where fertilisation occurs
(d) where implantation of embryo occurs.
(ii) Explain the role of pituitary and the ovarian hormones in menstrual cycle in human females. 
Answer. (i) Fig
(ii) Pituitary hormone:
(a) FSH stimulates maturation of follicle.
(b) Rapid secretion of LH (LH surge) induces rupture of Graafian follicle, thereby leading to ovulation (release of ovum).

Ovarian hormone:
(a) Estrogen stimulates follicular development.
(b) Progesterone produced by corpus luteum helps to maintain endometrium.
In the absence of fertilisation corpus luteum degenerates and the endometrium disintegrates leading to menstruation.

Please click on below link to download CBSE Class 12 Biology Human Reproduction Worksheet Set G