NIOS Biology Intext Solutions Chapter 21
INTEXT QUESTIONS 21.1
1. At what age do human males and females attain puberty?
Ans: Male 13-14 years; Female 11-13 years
2. Name the tubules present in the human testis.
Ans: Epididymis
3. Name the various parts of the following,
(i) Human male reproductive system
(ii) Human female reproductive system
Ans:
- (i) Testes, epididymis, vas deferens, urethra, penis
- (ii) Ovaries, fallopian tubes, uterus, vagina
4. Name the three types of accessory glands found in the human male reproductive system.
Ans: Seminal vesicles, prostate glands, Cowper’s glands
5. State the functions of the following.
(a) Seminal vesicles
(b) Prostate glands
(c) Uterus
(d) Cervix
Ans:
- (a) Stock sperms and provide them with nourishment
- (b) Secretes an alkaline fluid, a thin fluid that keeps the sperm alive and helps them to swim vigorously.
- (c) Inner lining receives, protects, and nourishes the embryo; contraction of the muscular wall expels the baby during birth.
- (d) Secretes a white, viscous, alkaline secretion that acts as a lubricant.
6. What is a gemmule? Explain its importance in the life of sponges.
Ans: Gemmule is a reproductive body for asexual reproduction in sponges. Gemmules help sponges overcome periods of drought and form new sponges when favourable conditions arise
7. State the functions of the following in insects:
(a) seminal vesicles in males
(b) spermatheca in female
(c) testes in males
(d) ovaries in females
Ans:
- (a) Seminal vesicles store sperm
- (b) receives sperm during copulation
- (c) generate sperms
- (d) produce eggs.
INTEXT QUESTIONS 21.2
1. State the main function of placenta.
Ans: It supplies oxygen and food from maternal blood to fthe oetus and transports carbon dioxide and excretory waste from foetal blood to maternal blood.
2. Define the following terms.
(i) Implantation.
(ii) Placenta.
(iii) Morula.
(iv) Amnion.
Ans:
- (i) The fixation of the morula in the wall of the uterus is called implantation
- (ii) Association between maternal and foetal tissue for physiological exchange: the developing embryo is attached to the uterus by a tissue called the placenta.
- (iii) Morula: The zygote begins to divide and form a mass of cells called the morula.
- (iv) Amnion: From the first few stages of development, the embryo is enclosed in a sac called the amnion.
3. Name the fluid surrounding the foetus in the uterus.
Ans: Amniotic fluid
4. Write the function of:
(a) Prolactin
(b) Oxytocin
Ans:
- Prolactin stimulates the synthesis of milk in the mammary glands in women soon after delivering a body.
- Oxytocin stimulates uterine contraction for childbirth and the squeezing of milk in mothers for the newborn infant
5. The first milk that comes out of the mammary gland of the mother is called ____. Why is this first milk important for the child?
Ans: Colostrum.
- It is rich in nutrients, fats, and proteins.
- Provides passive immunity
INTEXT QUESTIONS 21.3
1. List any four reasons for population explosion in India.
Ans:
- (i) Advancement in agriculture
- (ii) Religious and social customs
- (iii) Illiteracy
- (iv) Desire for a male child
2. What is the inter-relationship between population, environment, and development?
Ans: Overpopulation affects the environment and leads to its degradation, which in turn will affect development.Â
3. What is the effect of uncontrolled population growth on us and our nation?
Ans: A high population growth has severe environmental implications like over-crowding, decrease in per capita income, depletion of food, land, fuel and consumer resources.
Some such problems are listed below:
- Urbanization and environmental degradation.
- An increasing population leads to the depletion of mineral reserves.
- Increasing population cause depleting energy sources.
4. How does population growth influence urbanization and environmental degradation?
Ans: Due to an increasing population, farmlands in the rural areas can no longer support additional people. Thus, a large number of people migrate to urban areas with the hope of finding jobs and a better life. The subsequent increase in the urban population stresses the urban environment by increasing the number of squatter settlements and slums with no proper sanitation facilities, thus causing air, water, and soil pollution beyond permissible limits.
5. Relate the indiscriminate increase in population with the standard of living in our country.
Ans: A high population growth has severe environmental implications like over-crowding, decrease in per capita income, depletion of food, land, fuel and consumer resources.
