CBSE Class 10 Science How do humans reproduce Sure Shot Questions B

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HOW DO ORGANISMS REPRODUCE?

Very Short Answer type Short Questions

Question. Write the full expansion of HIV.
Answer : Human immuno-deficiency virus.

Question. What is vegetative propagation?
Answer : It is the formation of new plants from vegetative parts (e.g., stem, leaf, root, bud) of a parent plant.

Question. Name the life process of an organism that helps in the growth of its population.
Answer : Reproduction.

Question. What happens when a Planaria gets cut into two pieces?
Answer : Each piece grows (regenerates the missing parts) to form a complete animal.

Question. Name the hormone, secretion of which is, responsible for dramatic changes in appearance in girls when they approach 10-12 years of age.
Answer : Estrogen (= oestrogen) produced by growing follicles inside the ovary.

Question. In human female reproductive system where does fertilization occur?
Answer : In fallopian tube at ampulla—isthmus junction.

Question. Mention the common mode of reproduction found in
1. Amoeba
2. Planaria.
Amoeba Binary fission in any plane.
Answer : Planaria: Transverse binary fission.

Question. When a cell reproduces, what happens to its DNA?
Answer : DNA replicates and forms its copy at the time of cell reproduction.

Question. List two functions performed by ovaries in a human female.
Answer : 1. Formation of ova
2. Secretion of hormones, estrogen and progesterone.

Question. State the method used for growing rose plants.
Answer : Artificial method of vegetative propagation by stem cuttings and bud grafting.

Question. Name the part of Bryophyllum where buds are produced for propagation.
Answer : Leaf notches.

Question. No two individuals are absolutely alike in a population. Why?
Answer : Due to presence of variations.

Question. Why is variation important for a species?
Answer : Variation provides adaptability to changing environment and increased fitness in the struggle for existence.

Question. Flow does Planaria reproduce? Is this method sexual or asexual?
Answer : 1. Transverse binary fission and regeneration
2. Asexual method.

Question. “Cell division is a type of reproduction in unicellular organisms”. Justify.
Answer : In unicellular organisms cell division is a mode of reproduction as it produces two individuals or daughters by division of the parent cell.

Question. Why is fertilization not possible without pollination?
Answer : Fertilization requires bringing of male gametes to the female gamete which is possible only when pollen grain is brought from the anther to the stigma in the process of pollination.

Short Answer type Short Questions

Question. (a) Define pollination. Why is it necessary for reproduction in flower bearing plants?
(b) Write one reason to explain why cross pollination is preferred over self pollination?
Answer : (a) Pollination is the transfer of pollen grains from anther to the stigma. It is essential because the male gametes of flower bearing plants are nonmotile. On stigma a pollen grain germinates and sends male gametes to embryo sac by means of a pollen tube.
(b) Cross pollination produces variations and maintains vigour of the plants.

Question. What are the advantages of sexual reproduction over asexual reproduction?
Answer : “significance of Sexual Reproduction”
a. Due to reshuffling of chromosomes and crossing over, sexual reproduction brings about variations in almost all characters so that no two individuals are similar. Variations are essential for recognition, individuality and competitiveness. They may not protect individuals under adverse conditions but survival of species depends upon pre-adaptive variations.
b. Better Adaptability. Increased variability due to sexual reproduction is helpful to organisms in better adaptability to changes in environment.
c. Vigour and Vitality. It maintains the vigour and vitality of the individuals.
d. Harmful Traits. Harmful traits are often kept suppressed because of reshuffling of gene pairs that occurs during gamete formation and fusion.
e. Near Uniformity of Population. Due to the flow of genes amongst individuals during sexual reproduction, the uniformity of population is maintained where there is a broad resemblance of all the individuals with one another.
f. Genetic changes brought about by sexual reproduction play an important part in evolution of new forms.

Question. What is the effect of DNA copying which is not perfectly accurate on the reproductive process? How does the amount of DNA remain constant though each new generation is a combination of DNA copies of two individuals?
Answer : (a) Inaccuracy in DNA Copying . Even small errors of DNA copying produce variations or mutations. Some of these mutations may be drastic as to kill the cells and stop the reproductive process. Others are minor and form the basis of varied traits.
(b) DNA Amount: The parents are diploid (2n) as each of them has two sets of chromosomes (DNAs). They form haploid (n) male and female gametes through the process of meiosis. The haploid gametes have one set of chromosomes (DNAs). During fertilization, one male gamete fuses with one female gamete. It restores the diploid (2n) chromosome/DNA number in the offspring that is formed from fusion product or zygote (2n).

Question. Draw diagrams to explain the regeneration that takes place in each of the body parts of Planaria when its body is cut into three pieces. Name any other organism in which a similar process can be observed.
Answer : (a) 

(b) Hydra.

Question. On cutting the body of an organism into many pieces, it was observed that many of these pieces developed as new individuals. Name the process and list two organisms in which this process may be observed. Draw a schematic diagram to illustrate the changes that are likely to be observed during the development of new individuals in any one of the organisms named.
Answer : (i) Regeneration,
(ii) Planaria, Hydra.

Question. Write one difference between asexual and sexual modes of reproduction. Which species is likely to have better chances of survival, the one reproducing asexually or the one reproducing sexually? Justify your answer.
Answer : ( a) Difference: Asexual reproduction is mono parental, with no gametes, no meiosis and very little variations. Sexual reproduction is generally biparental involving fusion of gametes, meiosis and lot of variations.
(b) Better Chances of Survival. Sexually reproducing.
Reason:
1. Due to reshuffling of chromosomes and crossing over, sexual reproduction produces variations in almost all characters,
2. Sexual reproduction maintains as well as improves vigour and vitality of the individuals,
3. Variability and vitality are helpful to organisms in better adaptability to environment.

Question. (a) How would you relate the following methods to asexual reproduction?
1. Binary fission
2. Spore formation?
(b) State any advantage of using sexual reproduction over asexual reproduction.
Answer : (a) Asexual reproduction is the formation of new individuals from a part of a single parent without formation and fusion of gametes.
1. In binary fission a fully grown unicellular individual divides into two similar individuals or daughters directly.
2. In spore formation a single cell or sac of the parent produces a number of reproductive bodies which get dispersed and form new individuals on germination. There is no meiosis or gamete formation in both the cases.
(b) Advantage of Sexual Reproduction. Sexual reproduction introduces variations and maintains the vigour and vitality of the individuals.

Question. List four points of significance of reproductive health in a society. Name any two areas related to reproductive health which have improved over past 50 years in our country.
Answer : 1. People can lead a safe, responsible and satisfying reproductive life.
2. Provides protection from catching STDs.
3. Advantage of small family, care of the children as well as their proper upbringing
4. Less mortality among the new borns.
5. Maintenance of proper health of the mother and lesser chances of maternal mortality.
Improvement:
1. Reduction in the rate of population growth.
2. Decrease in the spread of STDs.
3. Adoption of small family norm.

Question. Name the type of asexual reproduction demonstrated by the following organisms:
(a) Amoeba
(b) Rhizopus
(c) Planaria
(d) Plasmodium
(e) Spirogyra
(f) Bryophyllum.
Answer : (a) Amoeba. Binary fission.
(b) Rhizopus. Spore formation or sporulation
(c) Planaria. Regeneration
(d) Plasmodium. Multiple fission,
(e) Spirogyra. Fragmentation
(f) Bryophyllum. Vegetative reproduction by foliar buds.

Question. Prevention. Sexually transmitted diseases can be prevented by use of mechanical barriers, especially condoms.
(a) Name the following:
1. Thread like non-reproductive structures present in Rhizopus.
2. Blobs, that develop at the tip of the non-reproductive threads in Rhizopus.
(b) Explain the structure and function of structures released from the blobs in Rhizopus.
Answer : (a) 1. Hyphae (singular hypha).
2. Sporangia (singular sporangium).
(b) The structures released by blobs or sporangia are spores. Spores of Rhizopus are thick walled dark coloured and multinucleate. They are dispersed by air. After falling on a suitable substratum, each spore gives rise to a new mycelium.

Question. List six specific characteristics of sexual reproduction.
Answer : a. Biparental
b. Meiosis
c. Haploid gametes
d. Fertilization
e. Diploid zygote
f. Variations.

Question. (a) Define germination.

(b) From the given diagram identify the incorrectly labelled parts.
Answer : (a) Germination. Beginning of growth or sprouting of a propagule like spore, seed or bud is called germination. It requires a particular set of external and internal conditions.
(b) Incorrectly Labelled Parts:
1. Male germ cell
2. Pollen grain
3. Pollen tube
4. Ovule.

Question. What are chromosomes? Explain how in sexually reproducing organisms the number of chromosomes in the progeny is maintained.
Chromosomes are linear strands of DNA and associated proteins that occur in nucleus of eukaryotic cells, carry genes and function in transmission of hereditary information.
Answer : The parents are diploid (2n) as each of them has two sets of chromosomes (DNAs).
They form haploid (n) male and female gametes through the process of meiosis. The haploid gametes have one set of chromosomes (DNAs). During fertilization, one male gamete fuses with one female gamete. It restores the diploid (2n) chromosome/DNA number in the offspring that is formed from fusion product or zygote (2n).

Question. Explain how surgical methods used for men and women respectively help in contraception.
Answer : Reversible Sterilisation: It is surgical technique that prevents passage of sperms in males and ova in females. The technique is called reversible because by another surgical procedure the passage-way can be restored. Reversible sterilisation is otherwise permanent method of contraception. It is of two types, vasectomy in males and tubectomy in females.
1. Vasectomy: The two vasa deferentia of the male are blocked by cutting a small piece and tying the rest. This prevents passage of sperms from testes into semen.
2. Tubectomy: A portion of both the fallopian tubes is excised or ligated to block the passage of ovum.

Question. What is the importance of DNA copying during reproduction? Why are offspring formed by asexual reproduction genetically similar to their parents?
Answer : Importance of DNA Copying: DNA carries hereditary information not only for controlling cellular functions but also all the structural and functional traits of organism. It is because of the latter that single celled zygote is able to form the whole multicellular organism. During reproduction there is formation of new cells which must carry the same amount and type of hereditary information as present in the parent cell. This is accomplished by DNA copying, which occurs prior to each cell division. DNA copying is not error proof. Errors give rise to variations.
Offspring formed by Asexual Reproduction. Asexual reproduction is uniparental. The genetic material present in the offspring is unaltered copy of DNA present in the parent. Therefore, they are genetically similar to the parents.

Question. Give reason as to why the following processes are different from each other,
(a) Fission in Amoeba and Plasmodium.
(b) Regeneration and fragmentation.
(c) Binary fission and fragmentation.
Answer : (a) Under favourable conditions Amoeba multiplies by binary fission while Plasmodium multiplies by multiple fission.
(b)

Question. Budding is type of asexual reproduction used by Hydra.
(a) What is meant by asexual reproduction? How is it different from sexual reproduction?
(b) Name any other type of asexual reproduction used by Hydra. Define it.
Answer : Budding is a mode of asexual reproduction in Hydra as the propagules is a bud or outgrowth of somatic body of the animal.
(a) Asexual reproduction is the formation of new individuals from specialized or unspecialized somatic parts of a single parent.
Difference: Asexual reproduction is monoparental, with no gametes, no meiosis and very little variations. Sexual reproduction is generally biparental involving fusion of gametes, meiosis and lot of variations.
(b) Regeneration: It is the ability of an individual to form lost or broken part, sometimes the entire individual from a piece of the parent body through dedifferentiation of mature cells and activity of reserve cells. The ability to form a new individual from a part of the body is well developed in simple animals like Hydra and Planaria. It is restricted to the formation of only broken parts in complex organisms.

Question. How does the uterus prepare itself and nurture the growing embryo? What happens when the egg is not fertilized?
Answer : Preparation: Under the influence of hormones from pituitary and growing Graafian follicle, the endometrium of uterus thickens, develops blood vessels and glands for nourishing the future embryo.
Nutrition for Growing Embryo. The contact region between embryo and endometrium grows into placenta. Placenta helps the embryo in obtaining nourishment (and oxygen) from blood sinuses of the uterus.
When Egg is not Fertilized: Glands present in the mucosa of uterine endometrium begin to degenerate. This sloughs off the endometrial lining, releasing a lot of mucus and blood. It is called menstruation. Menstruation lasts for 3-5 days.

Question. (a) A women had undergone surgical method for preventing unwanted pregnancies. Does this protect her from getting sexually transmitted diseases?
(b) How can AIDS be prevented?
Answer : (a) No, it does not prevent the coming together of body fluids during sex.
(b) Prevention of AIDS,
i. Use of barrier method of contraception like condom,
ii. Protection from getting infected, by blood contact like infected needles, syringes or transfusion,
iii. Proper sterilisation of dental equipment,
iv. Prevention of sexual contact with AIDS positive persons,
v. Prevention of pregnancy by AIDS positive patients.

Question. Rhizopus is an organism which reproduces by spore formation.
(a) What is meant by spore formation?
(b) What does the reproductive part or blob of Rhizopus contain?
(c) Why are these structures protected by thick walls?
Answer : ( a) Spore Formation. It is the formation of minute unicellular asexual reproductive disseminules which on germination give rise to new individuals.
(b) Blob or reproductive part of Rhizopus is sporangium. It contains spores.
(c) Thick Walls of Spores. Spores are dispersed by air currents. They have to face dry, hot, cold and other hostile conditions. Thick wall protects the spores from unfavourable environment.

Long Answer type Short Questions

Question. (a) Identify A, B and C in given diagram and write their functions,

(b) Mention the role of gametes and zygote in sexually reproducing organisms.
Answer : ( a) A-stigma: Reception of pollen grains and providing nutrients to pollen grains for their germination
B-pollen tube: Carrying of male gametes to inside the ovule for fertilization.
C-egg: Forms zygote and then embryo after fertilization.
(b) Gamete: It is haploid sex cell that brings traits in pure form from its parent for incorporation in the offspring. Zygote. Forms embryo.

Question. (a) Name the respective part of human female reproductive system
1. that produces eggs
2. where fusion of egg and sperm takes place and
3. where zygote gets implanted.
(b) Describe in brief what happens to the zygote after it gets implanted.
Answer : ( a)
1. Ovary
2. Fallopian tube (isthmus)
3. Uterus.
(b) Zygote/blastocyst after implantation grows to form embryo/foetus. The region of implantation forms placenta. The foetus remains attached to placenta by means of umbilical cord.
Through placenta, embryo is in contact with blood sinuses of the uterus for obtaining nutrients and elimination of wastes. The fully formed foetus undergoes parturition.

Question. (a) Draw a sectional view of human female reproductive system and label the following parts:
(b) 1. Where development of egg occurs
2. Where fertilization takes place.
Answer : (a)

Label
1. Ovary
2. Fallopian tube.
(b) 1. Endometrium thickens, becomes glandular and highly vascular. The contact region between embryo and uterine wall grows into placenta. Placenta helps the embryo in obtaining nourishment and oxygen from blood sinuses of the uterus. It also helps in transfer of wastes from embryo to the blood of the mother.
2. Glands present in the mucosa of uterine endometrium begin to degenerate. This sloughs off the endometrial lining, releasing a lot of mucus and blood. It is called menstruation. Menstruation lasts for 3-5 days.

Question. (a) Write the name of the human male reproductive organ that produces sperms and secretes a hormone.
Describe the changes the uterus undergoes
1. to receive the zygote
2. If zygote is not formed.
3. Name the hormone secreted and state its function.
(b) Write the site of fertilization and the part where the zygote gets implanted in the human female.
(c) State, in brief, how an embryo gets its nourishment inside the mother’s body.
Answer : (a) Testis. Hormone. Testosterone.
Function of Testosterone
1. Regulates sperm formation
2. Brings about puberty changes in males.
3. Maintains male secondary organs and traits.
(b) Site of Fertilization. Isthmus part of fallopian tube. Site of Implantation. Uterus.
(c) Nourishment of Embryo: Embryo gets nourishment from mother’s body with the help of placenta through a cord called umbilical cord. Placenta contains many finger-like villi from the chorion covering of the embryo. They occur in contact with blood sinuses of the mother present in the endometrial lining of uterus. All nutrients (glucose, amino acids, vitamins, etc.) diffuse from mother’s blood into villi and from there to embryo through the umbilical cord.

Question. (a) Write the function of placenta in human females,
(b) List four ways of preventing pregnancy. State two advantages of using such preventive methods.
Answer : (a) Placenta: It is a special double layered, spongy tissue connection between the foetus and uterine wall found in pregnant females. It has finger-like outgrowths or villi which are in contact with blood sinuses present in the uterine wall.
Role:
1. Attachment: Placenta attaches the foetus to uterine wall.
2. Villi: Placenta has finger-like outgrowths or villi which develop a large surface area for fixation and absorption.
3. Nutrients: Placenta picks up nutrients from mother’s blood and passes it to the blood of the foetus.
4. Waste Products: Waste products produced by the foetus passes out through the placenta into mother’s blood.
5. Gases: Foetus obtains oxygen supply from mother’s blood and eliminates carbon dioxide through placenta.
(b) Methods of Contraception:
1. Mechanical Barriers like condoms, cervical cap, diaphragm.
2. Oral Contraceptives or oral pills like Mala D, Saheli
3. Intrauterine Contraceptive Devices (IUCD) like loop, bow, Cu-T.
4. Surgical Methods like vasectomy in males and tubectomy in females.

Question. (a) Give an example each of a unisexual and a bisexual flower.
(b) Mention the changes a flower undergoes after fertilization.
How does the amount of DNA remain constant though each new generation is a combination of DNA copies of two individuals?
Answer : (a) Unisexual Flowers: Papaya.
Bisexual Flower: Mustard.
(b) DNA Amount: The parents are diploid (2n) as each of them has two sets of chromosomes
(DNAs). They form haploid (n) male and female gametes through the process of meiosis. The haploid gametes have one set of chromosomes (DNAs). During fertilization, one male gamete fuses with one female gamete. It restores the diploid (2n) chromosome/DNA number in the offspring that is formed from fusion product or zygote (2n).

Question. (a) Define fragmentation and regeneration,
(b) Can these two methods equated to be the same ? Answer with reason
(c) Give an example each of the organisms using the above methods.
Answer : (a) Fragmentation. It is breaking of an individual into two or more pieces with each piece growing to form the mature individual.
Regeneration. It is the ability of an individual to form lost or broken part, sometimes the whole individual.
(b) The two are not similar. Regeneration involves dedifferentiation, proliferation and differentiation to form lost parts. Fragmentation produces pieces where cells continue to divide resulting in growth of new individual. A repair is not involved.
(c) Regeneration. Hydra, Planaria. Fragmentation. Spirogyra, Marchantia.

Question. (a) Identify the leaf shown.

(b) Name the method used by the above leaf for reproduction.
(c) Give three advantages for the method used.
(d) Give two examples of plants which can be grown by this method.
Answer : (a) Bryophyllum
(b) Vegetative propagation
(c) 1. It is quicker method of propagation.
2. It gives rise to a genetically uniform propagation.
3. Good qualities of a variety can be maintained indefinitely.
(d) Sugarcane, Bougainvillea.

Question. Define the following processes:
(a) Fertilization
(b) Vegetative propagation
(c) Menstruation
(d) Regeneration
(e) Binary fission.
Answer : (a) Fertilization: The union of male gamete (sperm) with the female gamete (ovum) to form a diploid zygote is called fertilization.
(b) Vegetative Propagation: It is the formation of new plants from vegetative parts (e.g., stem, leaf, root, bud) of a parent plant.
(c) Menstruation: It is discharge of blood, mucus and broken pieces of endometrial lining in reproductively active females which occurs for 3-5 days at regular intervals of 28 days (lunar month). It occurs in response to non-fertilization of ovum and non-availability of progesterone hormone.
(d) Regeneration: It is ability of an individual to form lost or broken parts, sometimes the entire individual I from a piece of the parent body. The ability to form the whole individual from a piece of parent body is found only in simple animals like Hydra and Planaria. It does not occur in complex organisms like humans, birds, lizards etc. Here regeneration is limited to repair or regeneration of minor parts. It is because the tissues and organs are highly differentiated in complex animals.

Question. (a) Name the parts labelled A, B, C and D in the diagram.

(b) What is pollination? State its significance.
(c) How does fertilization occur in flowers? Name the parts of the flower that develop into
1. seed and
2. Fruit after fertilization.
Answer : (a) A—Pollen grain.
B—Pollen tube.
C—ovary.
D—Egg/oosphere.
(b) Pollination. The transfer of pollen grains from anther to the stigma of a flower is called pollination.
Significance- It carries the immobile pollen grains to the stigma for formation of male gametophyte and fertilization.
(c) After falling on a suitable stigma the pollen absorbs water and nutrients. It produces a pollen tube that grows through the style and reaches the ovary. Its tip contains a tube nucleus and two male gametes. The pollen tube enters an ovule, strikes against one synergid of the embryo sac and bursts open to release its contents. One male gamete fuses with the egg to form zygote while the other fuses with secondary nucleus to produce primary endosperm nucleus.
1. Seed—ovule,
2. Fruit—ovary.

Question. Justify the following statements :
(a) Variation is beneficial for the species over a period of time.
(b) New offspring produced are similar to their parents, but not identical
(c) Binary fission is different in Amoeba and Leishmania.
Answer : a) Many of the variations are pre-adaptations which have no immediate benefit to the individuals. However, they remain in the population. Whenever, environment undergoes a drastic change, the pre-adaptations present in some members of the population allow the latter to survive, grow and regain its former size. Therefore, it is not necessary that variations are beneficial to individuals developing them but can prove useful to the species.
(b) New offspring are similar to their parents because they have obtained the genetic traits from the same. They are, however, not identical because of chance separation, chance combination of chromosomes and recombination of genes due to crossing over.
(c) In Amoeba, binary fission can occur in any plane. In Leishmania the plane of division is vertical.

Question. (a) State in brief the function of the following organs in the human female reproductive system: Ovary, Fallopian tube, Uterus.
(i) What is menstruation? Why does it occur?
Answer : (a) 
i. Ovary: Formation of ova and secretion of hormones, estrogen and progesterone.
ii. Fallopian Tube: Passage of ovum, site for fertilization.
iii. Uterus: Implantation and nourishment of embryo.
(b) Menstruation:
It is discharge of blood, mucus and broken pieces of endometrial lining in reproductively active females which occurs for 3-5 days at regular intervals of 28 days (lunar month). It occurs in response to non-fertilization of ovum and non-availability of progesterone hormone.

Question. Explain what happens when :
(a) Testosterone is released in males
(b) Pollen grain falls on the stigma of the flower,
(e) Egg fuses with sperm cell,
(d) Planaria is cut into many pieces,
(e) Buds are formed at the notches of Bryophyllum leaf.
Answer : (a) Testosterone,
1. Regulates formation of sperms,
2. Puberty changes in boys.
3. Maintenance of secondary sexual characters in males.
(b) Pollen Grain. If pollen grain and stigma are compatible, the pollen grain absorbs water and nutrients from the stigma. It germinates and forms a pollen tube. Pollen tube passes into stigma and then style for reaching the ovary.
(c) Egg Fuses with Sperm Cell. The act is called fertilization. It produces a diploid zygote which later on grows into embryo.
(d) Cutting of Planaria. Each piece begins to regenerate, anterior end forms the anterior body parts, while posterior end gives rise to posterior body parts. Regeneration occurs with the help of stem cells and dedifferentiated cells (from differentiated ones).
(e) Bryophyllum Leaf. Buds present in the marginal notches of Bryophyllum leaf sprout and produce plantlets under suitable conditions. They help in vegetative multiplication.

Question. Differentiate between the following:
(a) Pollen tube and style,
(b) Fission in Amoeba and Plasmodium,
(c) Fragmentation and Regeneration,
(d) Bud of Hydra and Bryophyllum.
(e) Vegetative propagation and spore formation
Answer : (a) Pollen Tube and Style: Pollen tube is an outgrowth of pollen grain meant for carrying the male gametes to ovule. Style is a stalk-like structure of carpel (= pistil) that is meant for lifting the stigma above the level of ovary.
(b) Fission in Amoeba and Plasmodium: Under favourable conditions Amoeba multiplies by binary fission while Plasmodium multiplies by multiple fission.
(c) Fragmentation and Regeneration:
Fragmentation: It is breaking of an individual into two or more pieces with each piece growing to form the mature individual.
Regeneration: It is the ability of an individual to form lost or broken part, sometimes the whole individual.
(d) Bud of Hydra and Bud of Bryophyllum. In Hydra, bud is an outgrowth of the body which gets transformed into new animal that separates to lead an independent life. In Bryophyllum buds develop from the notches of the leaf. After falling on ground, the buds sprout and from plantlets.
(e) Vegetative Propagation and Spore Formation: In vegetative propagation new plants develop from specialised or unspecialised multicellular parts of the parent plant that function as propagules, e.g., Bryophyllum. Sugarcane. In spore formation, the individual parent produces unicellular reproductive bodies that get dispersed and form new individuals on germination, e.g., Rhizopus.

Question. (a) Write the functions of the following parts in human female reproductive system:
1. Ovary
2. Oviduct
3. Uterus.
(b) Describe the structure and function of placenta.
Answer : (a) 1. Ovary. Formation of ova and secretion of hormones, estrogen and progesterone.
2. Fallopian Tube. Passage of ovum, site for fertilization.
3. Uterus. Implantation and nourishment of embryo.
(b) Placenta: It is a special double layered, spongy tissue connection between the foetus and uternine wall found in pregnant females. It has finger-like outgrowths or villi which are in contact with blood sinuses present in the uterine wall.
Role:
1. Attachment: Placenta attaches the foetus to uterine wall.
2. Villi: Placenta has finger-like outgrowths or villi which develop a large surface area for fixation and absorption.
3. Nutrients: Placenta picks up nutrients from mother’s blood and passes it to the blood of the foetus.
4. Waste Products: Waste products produced by the foetus passes out through the placenta into mother’s blood.
5. Gases: Foetus obtains oxygen supply from mother’s blood and eliminates carbon dioxide through placenta.

Question. (a) What is vegetative propagation ? List with brief explanation three advantages of practising this process for growing some types of plants.
(b) Select two plants from the following which are grown by this process: Banana, Wheat, Mustard, Jasmine, Gram.
Answer : (a) Vegetative propagation is the formation of new plants by using vegetative parts of a parent plant as propagules e.g., stem (Sugarcane, Bougainvillea, Potato), root (Sweet
Potato, Dahlia), leaf (Bryophyllum), bud (Agave).
Advantages:
1. It is the only known method of multiplication of seedless plants like Banana and Sugarcane.
2. It is a quicker method as vegetatively reproduced plants bear flowers and fruits earlier than plants raised through seeds.
3. All the individual plants are clones of one another and their parent so that the crop is genetically uniform.
4. Good quality of a variety can be maintained indefinitely.
(b) Banana, Jasmine.

1. Mention the common mode of reproduction found in (i) Amoeba (ii) Planaria.

2. Name any two types of asexual reproduction.

3. Define reproduction.

4. Name two organisms that show asexual reproduction.

5. How does Hydra reproduce? Name another organism that reproduces by a similar method.

6. What is a spore?

7. Name two plants which reproduce through spores.

8. Why is regeneration considered a method of reproduction?

9. Which vegetative part is used in the propagation of Bryophyllum and mint?

10. Name two types of layering.

11. Name some plants where layering is used.

12. Which technique would you use for propagating improved varieties of mango and rose?

13. Name various types of asexual reproduction.

14. Mention the reproductive parts of a flower.

15. Define fertilisation.

16. What is self-pollination?

17. What is cross pollination?

18. What are the agents of pollination?

19. Which process results in formation of zygote?

20. What grows to form a fruit?

21. What is carpel?

22. Which parts of the flower transform into the seed and fruit?

23. What are gonads?

24. What is puberty?

25. When is ovum released in human female?

26. What is endometrium?

27. What is implantation?

28. What is parturition?

29. What is ovulation?

30. Where are the ova produced in woman?

31. Name two sex hormones.

32. What is the normal reproductive life in human female?

33. What are oral contraceptives?

Please click the link below to download CBSE Class 10 Science How do humans reproduce Sure Shot Questions B.