NIOS Biology Chapter 21 Reproduction and Population Control Terminal Exercises
The Reproduction and Population Control Class 12 NIOS chapter explains human reproduction, birth control methods, and population management. It discusses the importance of reproductive health, family planning, and social awareness.
Students learn scientific and social perspectives on population control. With solved terminal exercises, learners can practice exam-oriented questions effectively. This chapter is important for connecting biology with society, helping students prepare well for the NIOS Class 12 Biology examinations.
Reproduction and Population Control Class 12 NIOS
1. Define the following terms.
(i) Demography (ii) Vasectomy (iii) IUD
Demography: The scientific and statistical study of the human population. It deals with population growth, its composition (age, sex ratio), and its distribution in space.
Vasectomy: It is the ligation of the vas deferens through which sperm travel out of the epididymis, to prevent sperm from going out of the body.
IUD: IUD stands for Intra Uterine Devices, such as Copper T, which is inserted in the female body to prevent implantation.
2. Mention if the following statements are True (T) or False (F) and rewrite the wrong statements in the correct form.
(i) Fertilization occurs in the vagina.
(ii) Oxygen and nutrients diffuse from the mother’s blood into the foetus’s blood through the amniotic fluid.
(iii) Testes produce the testosterone hormone.
(iv) Pregnancy in women can be prevented by the method of vasectomy.
(v) Tubectomy involves the cutting and tying of the vas deferens in males.
(i) False
(ii) False
(iii) True
(iv) False
(v) True
3. Choose the odd one in each of the following.
(i) ovary; Fallopian tube; ureter; uterus
(ii) epididymis; urethra; vas deferens; uterus
(iii) Graafian follicle; corpus luteum; Leydig cell
(iv) amnion; corpus luteum; amniotic fluid; umbilical cord
(i) Ureter
(ii) Uterus
(iii) Leydig cell
(iv) Corpus luteum
4. Match the terms of Column I with those of Column II and write down the matching pairs.
Column I
Column II
1. Acrosome
(a) Testis
2. Ovulation
(b) Luteinizing hormone
3. Villi
(c) Spermatozoa
4. Fertilization
(d) Progesterone
(e) Placenta
(f) Vagina
4. Fertilisation
Ans: 1-(c), 2-(b), 3- (f), 4- (g)
5. What is reproduction? List the organs of the human male reproductive system.
Reproduction is the ability of living organisms by which they produce offspring of their own kind. The reproductive system in males consists of the following organs: a pair of testes, a pair of epididymis, a pair of vasa deferentia (singular: vas deferens), urethra, penis, and accessory glands.
6. What is a placenta? How is the placenta beneficial to the mother and the foetus?
The placenta serves as a tissue through which oxygen and food are supplied from the maternal blood to the foetus. It also transports carbon dioxide and excretory waste from the foetal blood to the maternal blood.
7. What is the significance of the testes being located in the scrotal sac outside the abdomen of human males?
The scrotum acts as a thermoregulator. It helps in maintaining the temperature of the testes at about 2-3°C lower than the body temperature. This temperature is suitable for the development of sperm.
8. Write in a sequence the region through which sperm travels from the seminiferous tubules up to the urethral opening in human males.
Seminiferous tubules in the testes produce sperm.
↓
Sperms pass to the vasa efferents through a network of tubules
↓
Sperms are stored in the epididymis in a viable but immotile stage.
↓
Vas deferens (sperm ducts)
↓
The urethra in the penis
9. How can the knowledge of the process of reproduction help in reducing population growth? Give reasons.
The most effective method for control of population is to impart education to the masses about the consequences of population explosion and make them aware of various ways of fertility control. Education helps to make people aware of the advantages of a small family and the disadvantages of a large family.
10. How does an increasing population affect the environment?
In order to meet the food requirements of the ever-increasing population of the country, new agricultural techniques have been adopted. Some of these have proved to be detrimental to the environment.
Due to deforestation, excessive irrigation, and natural hazards, such as floods, are frequent, land is being degraded, and wasteland is increasing.
The increased use of fertilisers and pesticides to boost agricultural productivity has immense adverse effects on the land and water resources of our country.
Agricultural land has been extensively polluted due to pollution from fertilizers and pesticides.
11. Name the following.
(i) The organ in which the foetus develops in a human female.
(ii) The male gamete in humans.
(iii) The fluid surrounding the developing embryo.
(iv) Stage when menstruation and ovulation stop in females.
(v) The surgical method of contraception in the human female.
(i) Uterus
(ii) Sperms
(iii) Amniotic fluid.
(iv) Menopause
(v) Tubectomy
12. Differentiate between the following.
(i) Implantation and pregnancy
(ii) Graffian follicle and corpus luteum
(iii) Identical twins and fraternal twins
(iv) Birth rate and death rate
(v) Vasectomy and tubectomy
(i) Implantation and pregnancy: This fixing of the embryo in the wall of the uterus is called implantation. Pregnancy is the state after implantation.
(ii) Graffian follicle and corpus luteum: The Graffian follicle is the mature egg, which is covered by follicular cells inside the antrum cavity. The empty follicle after the egg is released during ovulation is called the corpus luteum.
(iii) Identical twins and fraternal twins: When the zygote divides into two and they separate to develop into separate individuals, they are called identical twins. When two separate eggs are fertilised by different sperm cells and each grows into an individual, they are called fraternal twins.
(iv) Birth rate and death rate: Birth rate (natality) is the number of live births per 1000 individuals of the population per year. Death rate (mortality) is the number of deaths per 1000 individuals of the population per year.
(v) Vasectomy and tubectomy: Vasectomy is the ligation of the vas deferens through which sperm travel out of the epididymis, to prevent sperm from going out of the body.
Tubectomy is the sterilisation of a woman by cutting the fallopian tubes and ligating them so that an ovulated egg cannot pass down for fertilisation.
13. Draw the outline of the cross-section of the male reproductive system.
(i) Label the following parts.
(a) testis
(b) epididymis
(c) seminal vesicles
(d) vas deferens
(ii) Name the hormone produced by the testis.
(iii) Why are sperms produced in large numbers?
(iv) State the function of the seminal vesicles.
(i)
(ii) Testosterone
(iii) Sperms need to reach the ovum for fertilisation to happen, and as most of them fail to do so, the number of sperms produced is large.
(iv) Seminal vesicles store the sperm.
14. Write a note on:
(i) Lactation in humans
(ii) Gemmule
(iii) Cockroach ovaries
(i) Lactation in humans:
The secretion of milk from the mammary glands is called lactation.
The period during which the mammary gland secretes milk is called the lactation period.
The first secretion that comes out from the mammary glands of the mother, just after childbirth, is called colostrum.
Colostrum is rich in nutrients, fats, and proteins and also contains antibodies (Immunoglobulin A-IgA) that provide passive immunity to the newborn infant.
The synthesis of milk from the mammary glands is stimulated by the hormone prolactin, which is secreted by the anterior lobe of the pituitary gland.
Another hormone called oxytocin, secreted by the posterior lobe of the pituitary gland, stimulates the release of milk from the mammary glands.
(ii) Gemmule
Gemmule is a reproductive body for asexual reproduction found in freshwater sponges and some marine sponges.
A full-grown gemmule looks like a tiny hard ball containing an inner mass of undifferentiated cells called archaeocytes.
The archaeocytes are surrounded by a resistant covering that protects the inner cells.
The covering is made up of chitin and may be strengthened by spicules.
There is a small outlet called mMicropyle.
Gemules tide over the unfavourable conditions. For example, when the pond dries up or freezes during winter, when adult sponges die, it is the gemmules that remain viable. When the favourable conditions return, archaeocytes come out of the micropyle and develop and differentiate into a sponge.
(iii) Cockroach ovaries
The female reproductive system in cockroaches consists of a pair of ovaries, one on either side of the hind gut, embedded in the fat bodies.
Each ovary consists of blind tubes called ovarioles.
All the ovarioles unite posteriorly and open into a short lateral oviduct.
The two lateral oviducts unite to form a short median oviduct.