Class 10 Science
Chapter 8 How Do Organisms Reproduce
Previous Years Appeared Questions
MULTIPLE CHOICE QUESTIONS
1. Part of the flower that develops into fruit and part of the seed that develops into root respectively are (April 2019)
(A) ovary and plumule
(B) ovary and radicle
(C) plumule and radicle
(D) ovary and ovule
Ans: (B) ovary and radicle
2. In the given figure of Cotyledon the parts labelled as A and B respectively are (April 2020)
(A) fruit, shoot
(B) primary shoot, primary root
(C) secondary root, primary shoot
(D) bud, leaf.
Ans: (B) primary shoot, primary root
3. . The correct sequence found in the process of sexual reproduction in a flower is (July 2021)
(A) pollination, fertilization, seed, embryo
(B) seed, embryo, fertilization, pollination
(C) embryo, seed, pollination, fertilization
(D) pollination, fertilization, embryo, seed
Ans: (D) pollination, fertilization, embryo, seed
4. The embryo gets nutrition from the mother‘s blood with the help of a special part called (July 2021)
(A) Fallopian tube (C) Uterus
(B) Ovary (D) Placenta
Ans: (D) Placenta
5. The common passage for both sperms and urine in human male reproductive system is (July 2021)
(A) Urethra (C) Vas deferens
(B) Ureter (D) Urinary bladder
Ans: (A) Urethra
6. The parts that develop into fruit and seed in a flower respectively are (Sep 2021)
(A) stamen and ovary
(B) ovary and ovule
(C) ovule and ovary
(D) stamen and ovule
Ans: (B) ovary and ovule
7. In the human female reproductive system, the egg is carried from ovary to the uterus through this part (Sep 2021)
(A) cervix (B) fallopian tube
(C) placenta (D) vagina
Ans: (B) fallopian tube
8. A common bacterial infection that spreads through sexual contact in human beings is (Sep 2021)
(A) Gonorrhea (B) AIDS
(C) Hepatitis-B (D) Warts
Ans: (A) Gonorrhea
9. In humans, sexually transmitted viral infection is (April 2022)
(A) AIDS (B) Syphilis
(C) Tuberculosis (D) Gonorrhea
Ans: (A) AIDS
10. Part of a flower in the plant that develops into fruit is (June 2022)
(A) petal (B) stigma
(C) ovary (D) style.
Ans: (C) ovary
11. AIDS : Virus : : Warts : ______(KSEEB MQP 2023)
(A) Bacteria (B) Fungus
(C) Protozoan (D) Virus
Ans: (D) Virus
12. In humans, the testes are located outside the lower
abdomen in the scrotum because (April 2023)
(A) to protect testes from mechanical shocks
(B) to increase the production of sperms
(C) to maintain the secretion of testosterone hormone
(D) to maintain the temperature required for sperm
production.
Ans. :
(D) to maintain the temperature required for sperm
production.
13. Biological process that has been shown in the diagram is (June 2023)
(A) production of progenies by fragmentation method
(B) production of progenies by multiple fission method
(C) regeneration of tissues by development in specialised
cells
(D) asexual reproduction by vegetative propagation.
Ans. :
(C) regeneration of tissues by development in specialised
cells
ONE MARK QUESTIONS
1. In males, testes are located outside the abdominal cavity in scrotum. Why? (April 2022)
Ans. : Because to maintain lower temperature required for the formation of sperms than the normal body temperature.
2. Daughter cells generated by the division of bacterium cell are more similar to each other. How? (State Level Preparatory 2023)
Ans: The process of nuclear division in cells that produces daughter cells that are genetically identical to each other and to the parent cell
3. Write two examples for the organisms that reproduce by
binary fission. (April 2023)
Ans. :
Amoeba and Leishmania
TWO MARKS QUESTIONS
1. Draw the diagram showing the longitudinal section of a flower. Label the following parts : (April 2019)
(i) Style (ii) Anther.
Ans:
2. In sustaining reproductive fertility of a person,
(a) position of the testis in the body
(b) secretion of the testosterone
(c) secretion of the prostrate gland
are supplementary to each other. Explain scientifically. (June 2019)
Ans:
(a) Sperm formation requires a lower temperature than body temperature.
(b) Testosterone regulates / stimulates the formation of sperm.
(c) Secretion of Prostrate gland makes the transportation of sperm easier.
Thus reproductive fertility is sustained by the formation, stimulation to the formation and proper transportation of sperms.
3. Draw the diagram showing the germination of pollen on stigma and label the part on which pollination takes place. (June 2019)
Ans:
Ans. :
i) Testis : They produce sperms and testosterone hormone which is responsible for male characters.
ii) Scrotum : They regulate temperature necessary for production of sperms.
iii) Urethra and vas deferens : Transport sperm from testis.
iv) Prostate gland and seminal vesicle : They add their secretion to make the sperm transport easier and provide nutrition.
v) Penis : Delivers the sperms to the site of fertilization.
5. Explain the structure and important role of placenta during gestation period of woman. (April 2020)
Ans :
★ During pregnancy period the embryo gets nutrition from the mother‘s blood with help of disc shaped special tissue embedded in the uterine wall is called placenta.
★ It contains villi on the developing side of the tissue.
★ Villi provide glucose and oxygen to pass from mother to embryo.
★ Removes the wastes generated from the embryo.
6. How does menstruation occur ? (Sep 2020)
Ans. :
★ The uterus prepares itself every month to receive a fertilized egg and thus its lining becomes thick and spongy.
★ If the egg is not fertilized, the lining slowly breaks and comes out through the vagina as blood and mucous.
7. How does uterus prepare to receive the fertilized egg in woman ? What happens if egg does not fertilise ? Explain. (June 2022)
Ans:
★ Uterus prepares itself every month to receive fertilized egg. It makes its inner layer thick and spongy.
★ If the egg is not fertilized, it lives for about one day.
★ If fertilization doesn‘t occur the lining slowly breaks and comes out through the vagina as blood and mucous. ( Menstruation occurs )
8.
Ans : The reproduction methods expressed in both of the above figures are different from each other.
Spirogyra:
★Spirogyra reproduces by fragmentation
★ breaks up into smaller pieces upon maturation and these pieces grow into new individuals.
Planaria:
★ Planaria reproduces by regeneration.
★can be cut into any number of pieces and each piece grows into a complete organism.
THREE MARKS QUESTIONS
1. a) How is the vegetative propagation in plants useful to the field of agriculture?
b) Consistency of the DNA copying is important during reproduction. Why? (KSEEB MQP 2023)
Ans : a)
(i) Good qualities of a variety can be maintained indefinitely.
(ii) Vegetative propagation gives a genetically uniform population.
(iii) Plants raised by vegetative propagation can bear flowers and fruits earlier.
b) The consistency of DNA copying during reproduction is important for maintenance of body design features that allow the organism to use that particular niche [area where organisms live]. Reproduction is linked to the stability of population of species
2. a) How do germ cells receive half the amount of DNA? What is the need of this process?
b) How does menstruation in women occur?
(KSEEB MQP 2023)
Ans : a) Germ cells receive half the amount of DNA. This is achieved by a process of cell division called meiosis. When these germ-cells from two individuals combine during sexual reproduction to form a new individual, it results in reestablishment of the number of chromosomes and the DNA content in the new generation.
b) The uterus prepares itself every month to receive a fertilised egg. Its lining becomes thick and spongy. But if fertilisation does not occur then this lining of the uterus breaks down along with blood vessels. The degenerated part of uterus along with the blood moves out of the vagina in the form of bleeding, called menstruation.
3. “Reaching to sexual maturation is an essential event with respect to mammals like humans.” Substantiate this statement. (June 2023)
Ans. :
Reaching sexual maturation.
In males
★ Development of testes helps to produce sperm / testosterone
★ For reproduction requires development of testes
★ To have secondary sexual characters.
★ During intercourse erection of penis helps to transfer germ cells into the female body.
In females:
★ To cause menstrual cycle
★ For the production and release of ovum
★ For the secretion of women related hormones like estrogen
★ For the growth of breasts to feed the baby after a child birth.
FOUR MARKS QUESTIONS
1. a) Explain the development of fertilized egg into a foetus in a woman.
b)In humans, how the surgical contraceptive methods can be used to prevent pregnancy ? (Sep 2020)
Ans :
a)
★ The fertilized egg starts dividing and forms a ball of cells or embryo.
★ The embryo is implanted in the lining of the uterus where they continue to grow and develop organs to become foetus.
b)
★ If the vas deferens in the man is blocked, sperm transfer will be prevented. Fertilisation will not take place.
★ If the fallopian tube in the woman is blocked, the egg will not be able to reach the uterus. Fertilisation will not take place.
2. What is pollination ? What are the changes that occur in the
flower after pollination? (April 2023)
Ans. :
The transfer of pollen from the stamen to the stigma.
★ Germination of the pollen : Pollen tube develops.
★ Fertilization : Pollen grain enters the ovary through
pollen tube and fuses with the ovum / egg. Zygote is
formed.
★ Ovum develops into seed. Ovary grows rapidly and
ripens into fruit.
★ Petals, sepals, stamen, style and stigma may shrivel
and fall off.
FIVE MARKS QUESTIONS
1. a) What are the differences between the fragmentation and regeneration methods of reproduction? What is the reason for increased accumulation of variation in sexual reproduction?
b) Explain mensuration that occurs in women. (State Level Preparatory 2023)
Ans:
a)
★Fragmentation: The organism breaks-up into smaller pieces upon maturation, each piece develops into new individual. Ex: Spirogyra
★ Regeneration: If organism is somehow cut or broken into many pieces, each piece grows into a complete organism. Ex: Planaria
★ Because of recombination and mutation in DNA
b)
★ The uterus prepares itself every month to receive a fertilized egg and thus its lining becomes thick and spongy.
★ If the egg is not fertilized, the lining slowly breaks and comes out through the vagina as blood and mucous.
IMPORTANT QUESTIONS
1. What is puberty ?
Ans : The adolescence period in which reproductive tissues begin to mature is called Puberty.
2. What are the changes seen in girls at the time of puberty?
Ans : The various changes occur in girls at puberty are :
★ Hair grow under armpits and pubic region.
★ Mammary glands (or breasts) develop and enlarge.
★ The hips broaden.
★ Extra fat is deposited in various parts of the body like hips and thighs.
★ Fallopian tube, uterus and vagina enlarge.
★ Ovaries start to release eggs. g. Menstruation (monthly periods) starts.
★ Feelings and sexual drives associated with adulthood begin to develop.
3. DNA copying an essential part of the process of reproduction . Justify the statement
Ans :
★ To transmit the characteristics of parent organism to its offsprings (progenies)
★ While copying occasional variations are produced in offsprings ,
★ The changes in the copy of DNA provide an organism the capability to survive in changing conditions.
4. What is self-pollination and cross-pollination? Name the agents involved in this process.
Ans :
Self-pollination : If transfer of the pollen from stamen to the stigma occurs in the same flower, it is called as self-pollination.
Cross-pollination : If transfer of the pollen from stamen to the stigma occurs one flower to another flower, it is called as cross-pollination.
Pollination achieved by agents like wind, water or animals.
5. If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?
Ans : No , it won‘t help in protecting her from sexually transmitted diseases Copper-T is a contraceptive device which prevents union of sperm with egg.
6. What are the different methods of contraception?
Ans :
(i) Barrier method : In this method, condom, diaphragm and cervical caps are used. These prevent the entry of sperms in the female genital tract during sexual intercourse.
(ii) Chemical method : In this method a woman uses two kinds of pills (oral and vaginal pills). The oral pills are hormonal preparations which suppress the release of ovum in fallopian tube. These are called oral contraceptives. The vaginal pills/ creams are spermicidal. The chemicals kill the sperms during their journey in the vaginal tract.
(iii) Intrauterine contraceptive devices : Intrauterine contraceptive devices such as copper-T are placed safely in the uterus by a skilled doctor. It prevents the sperms to reach the uterus.
(iv) Surgical method : In this method, a small part of vas deferens of male and fallopian tube of female is cut or tied by surgery. It is called vasectomy in males and tubectomy in females.
7. What could be the reasons for adopting contraceptive methods?
Ans :
a) To control the birth rate and prevent the increase in population.
b) To reduce the adverse effects on mother‘s body due to frequent pregnancy.
c) To provide safety from sexually transmitted diseases.
8. In female reproductive system,
(i) How does an egg from the ovary reach uterus and develops into foetus?
(ii) What are the changes that occur in the uterus for the development of the foetus?
Ans :
(i) After sexual intercourse, sperm move from the vagina through the cervix and uterus to the fallopian tubes, where one sperm fertilizes the egg. The fertilized egg (zygote) divides repeatedly as it moves down the fallopian tube to the uterus. Then zygote divides repeatedly and becomes a solid ball of cells.
(ii) The inner lining of uterus thickens and its blood vessels enlarge to provide nourishment to the foetus. As pregnancy progresses, uterus expands to make room for the foetus.
9. In sexual reproduction,
(i) how does the re-establishment of DNA amount occur in the new generation?
(ii) how is the amount of variations increase among the individuals of each of the population?
Ans :
(i) When the gametes fuse during fertilization, the resulting new generation organism gets one pair of chromosome (Haploid) from each parent and thus the chromosome becomes diploid. Thus, the full number of chromosomes is re-established and the specific chromosome number of a species is maintained.
(ii) During fertilisation, gamete from each parent combines to form a zygote. Each gamete contains a different set of DNA. Because of recombination and mutation in DNA variations occur in an individual This variation of an individual transmitted to its population
10. Differentiate between bisexual and unisexual flowers.
Ans: Unisexual flowers contain male and female reproductive organs in separate flowers whereas bisexual flowers contain both male and female reproductive organs in the same flower.
11. Explain the process of budding in Hydra.
Ans:
★ In hydra, a bud develops as an outgrowth due to repeated cell division at one specific site.
★ These buds develop into tiny individuals
★ When fully mature, detach from the parent body and become new independent individuals.
12. Can you think of reasons why more complex organism cannot give rise to new individuals through regeneration?
Ans. The reason is that complex organisms are not merely random collection of cells.
★ The cells are specialized and are organized in them as tissues , organs and organ system.
★ These organs have to be placed at definite positions in the body.
★ So, regeneration is not possible in multi cellular organism.
13. Differentiate between asexual and sexual reproduction.
Ans:
14. Why is it said that sexual reproduction promotes diversity of characters in the off springs?
Ans.
★ It is because sexual reproduction results from the fusion of two gametes coming from two different and sexually distinct individuals.
★ This leads to variation and promotes diversity of characters in the off springs.
15. Protozoan reproduce by binary fission as well as by multiple fission. In your opinion which process is better and why?
Ans. Multiple fission is better than binary fission because:
★ More number of individuals is produced.
★ It helps to tide over unfavourable conditions.
16. What are the male and female gonads in human beings? Mention their functions
Ans : Testes are the male gonads Functions :
★ It secretes male hormone called testosterone
★ It produces male gametes (sperms)
Ovaries are the female gonads Functions :
★ It secretes female hormone called estrogen and progesterone
★ It produces female gametes (Ovum)
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