NIOS Class 12 Biology Chapter 21 Solution – Reproduction and Population Control
NIOS Class 12 Biology Solution Chapter 21 Reproduction and Population Control . NIOS Class 12 Biology Chapter 21 Question Answers Download PDF. NIOS Class 12 Biology Notes.
Board |
NIOS |
Class |
12th (Higher Secondary) |
Subject |
Biology |
Topic |
Question Answer, Solution, Notes |
INTEXT 21.1
1.) At what age do human males and females attain puberty?
Ans: Puberty ultimately leads to a stage when the child becomes an adolescent. sexual maturity is attained at the age of 13–14 years and in females, at the age of 11–13 years
2.) Name the tubules present in the human testis.
Ans: Epididymis is the tubules present in the human testis.
3.) Name the various parts of the following, (i) Human male reproductive system.. – Testes, epididymis, vas deferens, urethra, penis
(ii) Human female reproductive system – Ovaries, fallopian tubes, uterus, vagina
4.) Name the three types of accessory glands found in the human male reproductive system.
Ans: The accessory glands include seminal vesicles, prostate glands and Cowper’s glands
5.) State the functions of the following.
(a) Seminal vesicles – Stock sperms and provide them nourishment
(b) Prostate glands.- Secretes an alkaline fluid, thin fluid keeps the sperms alive and helps them to swim vigorously
(c) Uterus.- Inner lining receives, protects and nourishes embryo and helps in contractions of muscular wall expel baby during birth
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 overome periods of drought and form new sponges when favourable conditions arise
7.) State the functions of the following in insects:
(a) seminal vesicles in male – Secrete fluid which activates and nourishes sperms
(b) spermatheca in female- It receives sperms during copulation
(c) testes in males – It generate sperms
(d) ovaries in females- Produce ova and also secrete female sex hormones, oestrogen and progesterone
INTEXT 21.2
1.) State the main function of placenta.
Ans: The placenta is a connection of maternal and foetal tissue designed for some really crucial physiological exchange. Placenta transfers carbon dioxide and excretory waste from the foetal blood to the maternal blood as well as oxygen and nutrients from the mother’s blood to the foetus.
2.) Define the following terms.
(i) Implantation – The fixing of the embryo in the wall of the uterus is called implantation
(ii) Placenta – Placenta is an association between maternal and foetal tissue meant for some extermely important physiological exchange
(iii) Morula – The zygote begins to divide and form a mass of cells called morula
(iv) Amnion .- From the first few stages of development, the embryo is enclosed in a sac called amnion
3.) Name the fluid surrounding the foetus in the uterus.
Ans: The fluid surrounding the foetus in the uterus Amniotic fluid
4.) Write the function of:
(a) Prolactin – The hormone prolactin stimulates the production of milk by the mammary glands.
(b) Oxytocin- Oxytocin induces uterine contractions during childbirth and the mother’s production of milk for the newborn child.
5.) The first milk that comes out of the mammary gland of the mother is called . Colostrum . Why is this first milk important for the child?
Ans: . Because it is rich in nutrients, fats and proteins. Colostrum also contains antibodies (Immunoglobulin A-IgA) that provide passive immunity to the new born infant.
INTEXT 21.3
1.) List any four reasons for population explosion in India.
Ans(i) The agricultural sector’s advancements have boosted food availability, reducing starvation and malnutrition.
(ii) Advancement in industrialization helps in better storage and distribution of food
(iii) The development of medicine has made it possible to treat many different disorders.
(iv) Religous and social customs
TERMINAL EXERCISE
1.) Define the following terms.
(i) Demography : The statistical and scientific study of the human population is known as demography. It deals with population increase, its makeup (age, sex ratio), and its spatial distribution.
(ii) Vasectomy : A vasectomy is a surgical procedure. In order to stop sperm from leaving the body, a surgeon must ligate (knot) the vas deferens in men, which is where they exit the epididymis.
(iii) IUD: Intrauterine contraseptive devices such as copper T are inserted in the female body so that implantation is not possible
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 vagina. (F)
Ans: Fertilization occurs in fallopian tube.
(ii) Oxygen and nutrients diffuse from mother’s blood into foetus’s blood through amnion.(F)
Ans: Oxygen and nutrients diffuse from mother’s blood into foetus’s blood through placenta.
(iii) Testes produce testosterone hormone.(T)
(iv) Pregnancy in women can be prevented by the method of vasectomy.(F)
Ans: Pregnancy in women can be prevented by the method of Intrauterine devices such as copper T
(v) Tubectomy involves the cutting and tying of the vas deferens in male.(T)
3.) Choose the odd one in each of the following.
(i) ovary; Fallopian tube; ureter; uterus
Ans:Ureter
(ii) epididymis; urethra; vas deferens; uterus
Ans: uterus
(iii) Graafian follicle; corpus luteum; Leydig cell
Ans: Leydig cell
(iv) amnion; corpus luteum; amniotic fluid; umbilical cord
Ans: corpus luteum
4.) Match the terms of Column I with those of Column II and write down the
matching pairs.
Column i | Column ii |
Acrosome | Spermatozoa |
Ovulation | Progesterone |
Villi | Placenta |
Fertilization | Fallopian tube |
5.) What is reproduction? List tile organs of the human male reproductive system.
Ans: Reproduction is the process through which living things produce offspring of the same species.
organs of the human male reproductive system are as follow:
Testis
vas deferens
ejaculatory duct
Seminal vesicles etc
6.) What is placenta? How is the placenta beneficial to the mother and the foetus?
Ans: The placenta is a tissue connection between the mother’s and the fetus’s intended for a very significant physiological exchange. A placental tissue called the placenta connects the uterus to the developing embryo. The placenta acts as a tissue through which the foetus receives oxygen and nutrients from the mother’s blood. Additionally, it moves waste products and carbon dioxide from foetal blood to maternal blood.
7.) What is the significance of testes being located in scrotal sac outside the abdomen of human males?
Ans: The scrotum controls body temperature. It aids in keeping testicular temperature two to three degrees Celsius below body temperature. Sperm development is favourable at this temperature.
8.) Write in a sequence the region through which sperm travels from seminiferous tubules up to the urethral opening in human males.
Ans: (i) Sperm is produced by seminiferous tubules in the testes.
(ii) Sperms travel through a network of tubules to reach the vasa efferents.
(iii) They are kept in a viable but immature stage in the epididymis.
(iv)sperms travels through Vas deferens
(v) They get release through Urethra in penis.
9.) How can the knowledge of process of reproduction help in reducing population growth? Give reasons.
Ans: The most effective technique to manage the population is to educate people about the negative effects of population growth and the many methods of fertility control. Education aids in increasing public awareness of the . Benefits of a small family and Drawbacks of a Big Family
10.) How does increasing population affect environment?
Ans: Many people move to cities in search of employment and a better quality of life. As a result, the urban population rises. As the number of squatter communities and slums without sufficient sanitary services rises, the urban environment is put under stress because of the excessive pollution of the air, water, and soil that results.
11.) Name the following.
(i) The organ in which the foetus develops in a human female.
Ans:Uterus
(ii) The male gamete in humans.
Ans:Sperm
(iii) The fluid surrounding the developing embryo.
Ans: Amniotic fluid
(iv) Stage when menstruation and ovulation stops in females.
Ans: Menopause
(v) The surgical method of contraception in human female.
Ans: Tubectomy
12.) Differentiate between the following.
(i) Implantation and pregnancy
Ans: the fixation of morula in the wall of uterus is called implantation while, he two combine to produce a zygote if the ovum and sperm come into contact. Pregnancy is most likely to occur 13–14 days after the start of menstruation.
(ii) Graffian follicle and corpus luteum
Ans: The egg is covered in follicular cells, and an antrum-shaped cavity develops. This is the Graffian follicle, which is the mature egg while, the ovary releases the egg (ovulation), leaving the empty follicle known as the corpus luteum.
(iii) Identical twins and fraternal twins
Ans: If one egg is released and gets fertilized , after this, it divides into two, and the two cells then separate and start developing independently into two separate individuals. They are identical in all respects and called identical twins and When two sperms are used to fertilise two eggs, this can happen occasionally. These siblings are referred to as fraternal twins.
(iv) Birth rate and death rate
(v) Vasectomy and tubectomy
Ans: In order to stop sperm from leaving the body, a surgeon must ligate (knot) the vas deferens in men, which is where they exit the epididymis this is the method called vasectomy and Tubectomy is sterilization of the woman by cutting fallopian tubes and ligaturing them so that 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.
Ans: Testosterone
(iii) Why are sperms produced in large numbers?
Ans:Sperms are produce in large number to ensure the fertilization.
(iv) State the function of the seminal vesicles.
Ans: Seminal vesicles Secrete fluid which activates and nourishes sperms
14.) Write a note on:
(i) Lactation in humans
Ans: The process through which the mammary glands secrete milk is known as lactation, and the time frame in which this process occurs is known as the lactation period. The hormone prolactin, which is released by the anterior lobe of the pituitary gland, stimulates the production of milk from the mammary glands. The posterior lobe of the pituitary gland secretes oxytocin, a different hormone that induces the release of milk from the mammary glands.
(ii) Gemmule : Gemmule is a reproductive body for asexual reproduction in sponges. Gemmules help sponges overome periods of drought and form new sponges when favourable conditions arise
(iii) Cockroach ovaries : In cockroach ,the two sizable ovaries that make up the female reproductive system are located laterally in the second through sixth abdominal segments. Eight ovarian tubules, also known as ovarioles, make up each ovary, making a total of 16 ovarioles in each ovary.
Also See: Next Chapter No. 22 Question answer