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Karnataka State Syllabus Class 10 Science Chapter 8 How do Organisms Reproduce
KSEEB Class 10 Science How do Organisms Reproduce Intext Questions and Answers
Question 1.
What is the importance of DNA copying in reproduction?
Answer:
DNA in the cell nucleus is the information source for making proteins. These proteins lead to body design of an organism. If the organisms are to make offsprings that look very much like themselves, the DNA should replicate to make an exact copy of itself.
Question 2.
Why is variation beneficial to the species but not necessarily for the individual? ,
Answer:
Variations are sometimes useful for the survival of species in the ever-changing environmental conditions. Populations of organisms get well adapted to a particular niche. If these niches drastically change due to climatic changes or natural catastrophes, the populations of organisms could be wiped out too.
However, if some favourable variations were to be present in a few individuals in these populations. There would be some chance for their survival. Ex: When the water temperature in temperate regions increases due to global warming, the population of aquatic bacteria would die except a few variants resistant to heat.
Question 3.
How does binary fission differ from multiple fission?
Answer:
| Binary fission | Multiple fission |
| It is a type of asexual reproduction where a single cell divides into two daughter cells of equal size and each rapidly grows into an adult. Ex: Amoeba | In this type of asexual reproduction, cell divides several times by mitosis producing several nuclei and then multiple daughter cells |
Question 4.
How will an organism be benefited if it reproduces through spores?
Answer:
In some organisms like bread mould (fungi), thick-walled spores are formed which help them to survive unfavorable conditions these germinate on the availability of a suitable environment.
Question 5.
Can you think of reasons why more complex organisms cannot give rise to new individuals through regeneration?
Answer:
Regeneration is not the same as reproduction, since most organisms would not normally depend on being cut upto be able to reproduce. Hence more complex organisms cannot give rise to new individuals through regeneration.
Question 6.
Why is vegetative propagation practiced for growing some types of plants?
Answer:
Vegetative propagation is practised in some plants because
- Plants raised by vegetative propagation can bear flowers and fruits earlier than those produced from seeds.
- Plants such as banana, rose and jasmine that have lost the capacity to produce seeds can be propagated by vegetative propagation
- All the plantlets developed by vegetative propagation are genetically identical to their parent plant.
Question 7.
Why is DNA copying an essential part of the process of reproduction?
Answer:
DNA is the hereditary substance that makes proteins Proteins give rise to characteristic features of an organism. Copying of DNA results in transfer of information to form a complete organism.
Question 8.
How is the process of pollination different from fertilisation?
Answer:
Pollination takes place by agents like wind, water etc. But fertilisation do not require agents. In this way pollination is different from fertilisation.
Question 9.
What is the role of the seminal vesicles and the prostate gland?
Answer:
Secretions of the seminal vesicles and the prostate gland make the transportation of sperms easier and this fluid also provides nutrition.
Question 10.
What are the changes seen in girls at the time of puberty?
Answer:
In girls, breast size begins to increase, with darkening of the skin of the nipples at the tips of the breasts also girls begin to menstruate at around this time.
Question 11.
How does the embryo get nourishment inside the mother’s body?
Answer:
The embryo gets nourishment from the mother’s blood with the help of a special tissue called placenta. Placenta contains villi on the embryo’s side of the tissue. On the mother’s side are blood spaces, which surround the villi, This provides a large surface area for glucose and oxygen to pass from the mother to the embryo.
Question 12.
If a woman is using a copper-T, will it help in protecting her from sexually transmitted diseases?
Answer:
No, copper – T cannot help a woman in protecting her from sexually transmitted diseases.
KSEEB Class 10 Science How do Organisms Reproduce Textbook Exercise Questions and Answers
Question 1.
Asexual reproduction takes place through budding in
(a) amoeba.
(b) yeast.
(c) plasmodium.
(d) leishmania.
Answer:
(b) yeast.
Question 2.
Which of the follow ing is not a part of the female reproductive system in human beings?
(a) Ovary
(b) Uterus
(c) Vas deferens
(d) Fallopian tube
Answer:
(c) Vas deferens
Question 3.
The anther contains
(a) sepals.
(b) ovules.
(c) carpel.
(d) pollen grains.
Answer:
(d) pollen grains.
Question 4.
What are the advantages of sexual reproduction over asexual reproduction?
Answer:
Sexual reproduction results in addition of variations to the population which ultimately contribute to evolution. Since no genetic variations occur among the offsprings asexual reproduction has a lesser significance for evolution of species.
Question 5.
What are the functions performed by the testis in human beings?
Answer:
Germ cells are produced in 1 testes and these testes secrete a hormone called testosterone.
Question 6.
Why does menstruation occur?
Answer:
The menstrual cycle occurs due to the rise and fall of hormones such as luteinising hormone and follicle stimulating hormone, this cycle results in the thickening of the lining of the uterus, and the growth of an ovum. Ovum is released in the middle of the cycle. If it is not fertilised by a sperm, the uterine lining is broken down and comes out through vagina as blood and other fluids. This is known as menstruation.
Question 7.
Draw a labelled diagram of the longitudinal section of a flower.
Answer:
Question 8.
What are the different methods of contraception?
Answer:
Methods of contraception.
- In mechanical barrier method, ovum and sperms are Prevented from physically meeting.
Ex: Use of condoms. - Certain drugs are taken orally as pills, change the hormonal balance of the body so that ova are not released, thus preventing conception.
- Insertion of intra uterine devices such, as copper – Tin uterus can – prevent pregnancy.
- In surgical method, the vas deferens in the male is removed or tied up, whereas the fallopian tube in females is removed or tied up respectively, to prevent the transfer of gametes to the site of fertilisation.
Question 9.
How are the modes for reproduction different in unicellular and multi r cellular organisms?
Answer:
Unicellular organisms mostly reproduce asexually. Fission and budding are the common modes of asexual reproduction. Most of the multicellular organisms reproduce sexually. This involves the formation and fusion of gametes. Some primitive multicellular organisms can reproduce asexually also.
Ex: [Hydra by budding and Regeneration in planaria]
Question 10.
How does reproduction help in providing stability to populations of species?
Answer:
Reproduction is the process of producing new individuals of the same species by existing individuals of a species. So, it helps in providing stability to populations of species by bringing a balance between rate of birth and death in a given population. The rate of birth should be approximately equal to the rate of death.
Question 11.
What could be the reasons for adopting contraceptive methods?
Answer:
Advantages of adopting contraceptive method
- Contraceptive methods prevent unwanted pregnancy.
- They are adopted to delay or space pregnancy.
- Certain contraceptives like condoms protect the user from contracting sexually transmitted.
Diseases like AIDS. Contraceptive methods have a significant role in checking uncontrolled growth of population.
Question 12.
What is Germination?
Answer:
The embryo present in the seed develops into a seedling under appropriate conditions. This process is known as germination.
Match the following:
Question 1.
| A | B |
| 1. Budding | a) Rhizopus |
| 2. Regeneration | b) Leish mania |
| 3. Spore formation | c) Planaria |
| 4. Sexual Reproduction | d) Amoeba |
| e) Hydra | |
| f) Hibiscus | |
| g)plasmodium |
Answer:
- e) Hydra
- c) planaria
- a) Rhizopus
- f) Hibiscus
Multiple choice questions:
Question 1.
Fission is a
a) Type of reaction
b) Type of Asexual reproduction
c) Type of plant
d) Type of Animal
Answer:
b) Type of Asexual reproduction
Question 2.
Which of the following can regenerate its lost body part.
a) Hydra
b) Spirogyra
c) Rhizopus
d) Planaria
Answer:
d) Planaria
Question 3.
Reproduction part of the plant
a) Stem
b) Root
c) Leaf
d) Flower
Answer:
d) Flower
Question 4.
Male reproduction part of flower
a) Stigne
b) Staman
c) Style
d) None of these
Answer:
b) Staman
Question 5.
Malaria causing parasitic reproduces 7. in human by
a) Fragmentation
b) Multiple fission
c) Fission
d) Binary fission
Answer:
b) Multiple fission
Question 6.
Female reproduction part of flower
a) Stigma
b) Style
c) Stamen
d) All the above
Answer:
a) Stigma
Question 7.
Spirogyra reproduces by
a) Fragmentation
b) Budding
c) Spore
d) Fission
Answer:
a) Fragmentation
Question 8.
Only one parent is needed for
a) Sexual reproduction
b) Pollination
c) A sexual reproduction
d) None of these
Answer:
c) A sexual reproduction
KSEEB Class 10 Science How do Organisms Reproduce Additional Questions and Answers
Question 1.
What is asexual reproduction?
Answer:
It is a mode of reproduction in which a single parent is capable of producing offspring.
Question 2.
What is fragmentation? Give an example.
Answer:
In some organisms, if the body breaks into distinct pieces each fragment grows into an adult. This mode of asexual reproduction is called fragmentation. Ex: Spirogyra
Question 3.
How does leishmania reproduce asexually?
Answer:
In Leishmania, binary fission occurs in a definite orientation in relation to the position of structures like flagellum, to produce daughter cells.
Question 4.
Explain the process of regeneration in planaria.
Answer:
If an individual planaria is somehow cut into many pieces, each piece grows into a complete organism. Specialised cells in the body of planaria proliferate and make large numbers of cells. These cells undergo differentiation to become various tissues, finally leading to the formation of entire body.
Question 5.
Explain the mode of asexual reproduction in hydra.
Answer:
In hydra, a bud develops as an outgrowth due to repeated cell division at one specific site. These buds develop into tiny individuals and when fully mature, detach from the parent body and become new independent individuals.
Question 6.
Name the plant that reproduces through leaves. Is there any advantage from this way of reproduction?
Answer:
Bryophyllum reproduces asexually by producing buds in the notches along the leaf magin. A large number of young plants are produced by a single leaf, when the leaf falls on the soil the plantlets develop into new plants that help the survival of species.
Question 7.
What is tissue culture?
Answer:
Tissue culture is a technology to grow new plants which involves separating cells or tissues from a plant and grow them in a test tube, aseptically in a nutrient media.
Question 8.
The structure that does not belong to group is
a) Sporangium
b) Testes
c) Hyphae
d) Seed.
Answer:
c) Hyphae
Question 9.
Why are testes located outside the abdominal cavity?
Answer:
Testes are located outside the abdominal cavity in scrotum because sperm formation requires a lower temperature than the normal body temperature
Question 10.
In which part of the female reproductive system does implantation of zygote takes place?
Answer:
The zygote gets implanted in the lining of uterus or womb.
Question 11.
Draw neat labelled diagrams of human – male and female reproductive systems respectively
Answer:
Question 12.
Give two examples for STDS caused by bacteria.
Answer:
Sexually transmitted diseases caused by bacteria are gonorrhea and syphilis.
Question 13.
Functions of the following
a) petals of a flower
b) pollen grains
c) Micropyle
Answer:
a) Attract the insect for pollination
b) Fertilize the egg cell present in the embryo sac.
c) Entry of the pollen tube in the ovule
Question 14.
Name of part of Bryphylum where the buds are produced.
Answer:
Leaf notches
Question 15.
Write two advantages of vegetative propagations.
Answer:
- Only one parent is required.
- Plants that can not produce seeds
Question 16.
What happens to the ovule and the ovary after fertillization.
Answer:
After fertillization ovule changes to seed and ovary to fruit.
Question 17.
Functions of the following:
1) Redicle
2) Plumule
3) Cotyledon
Answer:
- Future root
- Future stem
- Food store
Question 18.
Differentiate pollen grain and ovules.
Answer:
- Pollen grain produce male germ cells
- Ovule produce female germ cell.
Question 19.
Name
1. Thread like non-reproductive structures present in Rhizopus
2. Blob that develops at tips of the non- reproductive threads in Rhizopus.
Answer:
- FIyphae
- Sporangia
Question 20.
Draw labelled diagram of Germination of pollen on stigma.
Answer:
