Chapter 7: How do Organisms Reproduce?

Important questions — the ones the board asked most (20)

1. Q1Long answer5 marksAsked: 2023

   (a) Name the parts of a bisexual flower that are not directly involved in reproduction. (b) Differentiate between self pollination and cross pollination. List any two significance of pollination. (c) What is the fate of ovules and ovary after fertilization in a flower ?

   

   Medha Ma’am

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   Watch it on the board · 80 s

   Model answer

   1. 1.(a) The sepals (calyx) and petals (corolla) are not directly involved in reproduction.1 mark
   2. 2.(b) In self-pollination, pollen is transferred from the anther to the stigma of the same flower (or another flower of the same plant).0.5 marks
   3. 3.In cross-pollination, pollen is carried from the anther of a flower of one plant to the stigma of a flower on another plant of the same species, by agents such as insects, wind, water or birds.0.5 marks
   4. 4.Pollination brings the pollen grains, which carry the male germ cells, to the stigma, making fertilisation possible.0.5 marks
   5. 5.It leads to the formation of seeds and fruits, and cross-pollination brings variation into the offspring.0.5 marks
   6. 6.(c) After fertilisation, the ovule develops a tough coat and becomes a seed containing the future plant (embryo).1 mark
   7. 7.The ovary grows rapidly and ripens to form a fruit.1 mark

   Marks split from a structure derived from past papers (checked twice); not CBSE’s official scheme

2. Q2Long answer5 marksAsked: 2026

   16. (a) Given below are some specific situations. Analyse and describe what will happen when : (i) Spores are released from the tiny bud-like (round) structures of bread mould ? (ii) Leaves of Bryophyllum fall on wet (moist) soil ? (iii) Pollen grains of a different species land on the stigma of a plant ? (iv) Copper-T is placed in the uterus of a woman ? (v) Spirogyra grows and breaks into smaller fragments ? Or (b) Given below are some specific situations. Analyse each and describe its possible effect (impact) : (i) A population of bacteria lives in temperate water whose temperature is rising due to global warming. (ii) When a sperm reaches the oviduct of a woman (female human), it encounters (meets) an egg. (iii) Flowers which have only the gynoecium (pistil) do not undergo self-pollination. (iv) Fertilisation of the egg does not take place in a woman. (v) When a seed is sown (put) in soil having adequate amount of water and air.

   

   Medha Ma’am

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   Hear it from Medha Ma’am · 175 s

   Model answer · Reproduction situations, analysis

   1. 1.(b)(i) Rising water temperature from global warming will kill most of these bacteria, because the place they are suited to has changed drastically. A few variants are resistant to heat. They have the variation to tolerate the higher temperature, so they will survive and reproduce while the others die. So variation is useful for the survival of species over time.1 mark
   2. 2.(b)(ii) The sperm fuses with the egg in the fallopian tube (oviduct). This is fertilisation, and it forms a zygote. The zygote divides again and again to form an embryo. The embryo moves down to the uterus and gets implanted in the uterine wall, where it is nourished and grows.1 mark
   3. 3.(b)(iii) These flowers are unisexual because they contain only the pistil and no stamens. They cannot get pollen from the same flower, so they undergo cross-pollination: pollen is brought from another flower by agents like wind, water or animals such as insects. Since two individuals take part, the offspring show greater variation.1 mark
   4. 4.(b)(iv) Every month the uterus prepares a thick and spongy lining to receive and nourish a fertilised egg. If the egg is not fertilised, this lining is not needed. It slowly breaks down and comes out through the vagina as blood and mucus. This is called menstruation.1 mark
   5. 5.(b)(v) With an adequate amount of water and air, the seed germinates. The radicle grows into the root and the plumule grows into the shoot, while the cotyledons supply stored food to the growing seedling until it can make its own food.1 mark

   • In (i), write that "the few variants resistant to heat" survive and reproduce, and end with "variation is useful for the survival of species".
   • In (ii), write the full sequence: fertilisation, then zygote, then embryo, then "implanted in the uterine wall".
   • In (iv) and (v), name the result: "menstruation" for the unfertilised egg, and radicle → root, plumule → shoot, cotyledons → food for the germinating seed.

   Marks split from a structure derived from past papers (checked twice); not CBSE’s official scheme

3. Q3Case-based5 marksAsked: 2026

   Attempt either (a) or (b) : (a) Observe the given diagram and answer the questions that follow : (i) Give the name of the structure and type of reproduction shown in the above diagram. (ii) State one advantage and one disadvantage of the above mentioned method of reproduction. (iii) Give reason : Asexual reproduction lacks genetic variation. (iv) Why have higher organisms resorted to sexual reproduction in spite of its complexity ? OR (b) Observe the given diagram and answer the questions that follow : (i) Give the name and type of reproduction shown in the above diagram. (ii) Comment on the processes taking place in stage P. (iii) Name an organism which reproduces by the above mentioned method. (iv) Name the method that can be used to raise plants that have lost their capacity to produce seeds. List any two advantages of growing plants by such a method.

   

   Medha Ma’am

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   Hear it from Medha Ma’am · 145 s

   Model answer · Vegetative propagation, Bryophyllum leaf

   1. 1.(a) (i) The structure shown is a leaf of Bryophyllum with buds in the notches along the leaf margin. These buds fall on the soil and develop into new plants.0.5 marks
   2. 2.The type of reproduction shown is vegetative propagation, which is a form of asexual reproduction.0.5 marks
   3. 3.(ii) Advantage: All plants produced are genetically similar enough to the parent plant to have all its characteristics, so the desirable traits of the parent are kept.1 mark
   4. 4.Disadvantage: There is no genetic variation among the new plants. If their surroundings change badly, all of them may be wiped out together.1 mark
   5. 5.(iii) Asexual reproduction lacks genetic variation because the new generation is created from a single individual. Only the DNA of a single parent is involved and there is no fusion of gametes, so the offspring have the same genetic makeup as the parent.1 mark
   6. 6.(iv) Higher organisms have taken up sexual reproduction, even though it is complex, because it involves two individuals and creates genetic variation. If the niche changes, for example if temperature or water levels change, some variants have a chance to survive. So variation is useful for the survival of species over time and drives evolution.1 mark

   • In (i), give both answers: the structure is a "leaf of Bryophyllum" and the type is "vegetative propagation", which is asexual.
   • In (iii), write that the DNA of "a single parent" is involved and there is "no fusion of gametes".
   • In (iv), give all three ideas: genetic variation, "survival of species" when the niche changes, and evolution.

   Marks split as in the board’s published marking scheme

4. Q4Long answer5 marksAsked: 2025

   35. (A) (i) What is regeneration? Give one example of an organism that shows this process and one organism that does not. Why does regeneration not occur in the latter? (ii) Water in a pond appears dark green and contains filamentous structures. Name these structures and the method by which they reproduce. Explain the process. OR (B) (i) Name the part performing following functions in human male reproductive system : (a) Carries sperm (b) Production of male gametes (c) Whose secretion makes the transport of sperms easier (d) Provide suitable temperature for sperm formation (ii) Write any two characteristics of sperms. (iii) What are surgical contraceptive methods? Give the side effect caused by this procedure.

5. Q5Long answer5 marksAsked: 2025

   (A) Name the parts marked as 'A' and 'B' in the given diagram. Write in detail the changes that take place in a flower when the product of 'B' reaches 'A' till a fruit is formed. OR (B) In human female reproductive system state the changes that take place once fertilisation has taken place. Write the role of placenta in this process. What happens when the egg is not fertilised ?

   How the model answer begins

   1. (A) A is the stigma and B is the anther. OR (B) After fertilisation the zygote is implanted in the thick lining of the uterus and begins to divide.

   The full answer from Medha Ma’am →
6. Q6Long answer5 marksAsked: 2025

   (a) Define Puberty. List any two changes seen in boys at the time of puberty. (b) Why are testes in human males located outside the abdominal cavity in scrotum ? (c) List any three techniques of contraception used by humans. Which one of these is not meant for males ? OR (a) Name the part performing following functions in human female reproductive system : (i) production of eggs (ii) site of fertilization (iii) site of implantation (iv) entry of the sperms (b) What changes are observed in the uterus : (i) subsequent to implantation of zygote and (ii) if an egg does not get fertilized ?

   How the model answer begins

   1. (a) Puberty is the period during adolescence when the rate of general body growth begins to slow down and reproductive tissues begin to mature.

   The full answer from Medha Ma’am →
7. Q7Long answer5 marksAsked: 2025

   35. (a) Name the method by which Amoeba and Leishmania reproduce. Write a major difference in the way they divide to produce new individuals. (b) What is asexual reproduction ? Explain the process of budding in Hydra. (c) Give two methods used to grow rose and jasmine plants by vegetative propagation. OR (a) Write one function each of the parts - (i) petals (ii) anther (iii) style and (iv) ovary of a bisexual flower. (b) Give one example each of a unisexual flower and a bisexual flower. Mention the changes which a flower undergoes after fertilization.

   How the model answer begins

   1. (a) Amoeba and Leishmania reproduce by binary fission. Amoeba can divide in any plane, whereas Leishmania, which has a whip-like flagellum at one end, divides in a definite (lengthwise) plane in relation to it. OR…

   The full answer from Medha Ma’am →
8. Q8Long answer5 marksAsked: 2024

   35. (A) (i) Name three techniques/devices used by human females to avoid pregnancy. Mention the side effects caused by each. (ii) What will happen if in a human female (a) fertilisation takes place, (b) an egg is not fertilised ? OR (B) (i) Draw a diagram showing spore formation in Rhizopus and label the (a) reproductive and (b) non-reproductive parts. Why does Rhizopus not multiply on a dry slice of bread ? (ii) Name and explain the process by which reproduction takes place in Hydra.

   How the model answer begins

   1. (A)(i) Barrier methods such as the condom or diaphragm; side effect: occasional irritation or allergy, and failure if torn. OR (B)(i) Diagram: thread-like hyphae on the bread, with erect stalks ending in round sporangia…

   The full answer from Medha Ma’am →
9. Q9Long answer5 marksAsked: 2023

   (i) Name the two modes of asexual reproduction observed in Hydra and explain them. (ii) What is vegetative propagation ? List two advantages of using this technique.

10. Q10Long answer5 marksAsked: 2026

    (a) Given below are certain situations. Analyse each and describe its possible impact : (i) A population of bacteria living in temperate waters whose temperature increased by global warming. (ii) The sperm encounters the egg when it reaches the oviduct in human females. (iii) Self pollination does not occur in a flower that contains only pistil. (iv) Egg does not get fertilised in a human female. (v) When the seed is placed under appropriate condition of water and air in the soil ? OR (b) Given below are certain situations. Analyse and describe what would happen when : (i) Spores are liberated from blob-like structures of the bread mould? (ii) Leaves of bryophyllum fall on wet soil ? (iii) A pollen from different species land on the stigma of totally unrelated species ? (iv) Copper-T is placed in the uterus of a human female ? (v) Spirogyra breaks into smaller fragments upon maturation ?

    How the model answer begins

    1. (a) (i) When global warming raises the temperature of the temperate waters, most of these bacteria would die, but the few variants resistant to heat would survive and grow further.

    The full answer from Medha Ma’am →
11. Q11Short answer5 marksAsked: 2026

    Attempt either (a) or (b) : (a) (i) Name an organ that helps in the formation of male germ cells in humans and also mention the condition that favours the formation of male germ cells. (ii) In male reproductive system, write the pathway followed to deliver male germ cells to the site of fertilisation. (iii) Mention the main physical feature of the male germ cell that helps it move towards the female germ cell. OR (b) Radha has three children. She does not want to have more children. Radha visits a nearby hospital, to know the methods to prevent pregnancy. (i) Mention the name of any two ways other than the surgical methods, following which Radha can avoid unwanted pregnancies. (ii) Name the surgical methods to prevent pregnancy. (iii) Give one example each of sexually transmitted diseases caused by bacteria and virus.

    How the model answer begins

    1. (a) (i) In humans, the testes are the organ that helps in the formation of male germ-cells, or sperms.

    The full answer from Medha Ma’am →
12. Q12Long answer5 marksAsked: 2026

    (a) Answer any one from (a) or (b) : (a) (i) Name the accessory organ in the human body that helps in the formation of male germ cells and also mention the condition that helps in the formation of male germ cells. (ii) Name the path in the male reproductive system that helps in transporting male germ cells to the site of fertilization. (iii) Mention the main physical (structural) feature of the male germ cell that helps it to move towards the female germ cell. OR (b) Radha has three children. She does not want more children. Radha goes to a nearby hospital to know about the methods of contraception. (i) Suggest any two methods other than surgical methods that Radha can adopt to avoid unwanted pregnancy. (ii) Name the surgical techniques of contraception. (iii) Give one example each of bacterial and viral sexually transmitted diseases.

    How the model answer begins

    1. (a)(i) Male germ cells (sperms) are formed in the testes. OR (b)(i) A barrier method such as a condom or diaphragm.

    The full answer from Medha Ma’am →
13. Q13Long answer5 marksAsked: 2026

    16. (A) (i) In an angiospermic flower, fertilization is said to take place when male gametes carried in the pollen tube fuse with the female gamete, present in the embryo sac. This results in lot of changes in different parts of the flower. State the changes taking place in the following structures of flower post fertilization : (a) Zygote (b) Ovule (c) Ovary (d) Sepals (ii) Define germination. OR (B) (i) Sugarcane does not produce seeds so name the process through which it will be able to reproduce. (ii) List any two advantages of this method. (iii) Besides sugarcane, give two more examples of plants that reproduce by this method. (iv) Why regeneration is not possible in all the types of animals ?

    How the model answer begins

    1. (i) (a) Zygote: After fertilisation, the zygote divides several times to form an embryo within the ovule. This embryo is the future plant.

    The full answer from Medha Ma’am →
14. Q14Long answer5 marksAsked: 2025

    (a) (i) Write the functions of the following parts of human female reproductive system : (I) Ovary (II) Fallopian tube (III) Uterus (ii) State briefly two contraceptive methods used by human males. OR (b) (i) Differentiate between self-pollination and cross-pollination. (ii) Identify A, B and C in the diagram given below and write one function of each.

15. Q15Very short answer5 marksAsked: 2025

    (b) (i) Differentiate between self-pollination and cross-pollination. (ii) Identify A, B and C in the diagram given below and write one function of each.

    How the model answer begins

    1. Self-pollination is the transfer of pollen grains to the stigma of the same flower. This transfer of pollen occurs in the same flower, so self-pollination involves only one parent plant and no genetic variation is…

    The full answer from Medha Ma’am →
16. Q16Long answer5 marksAsked: 2025

    35. (a) (i) Identify the parts 'X' and 'Y' in the figure given below : (ii) Name the yellowish coloured structures produced by the part labelled as 'Y'. (iii) Write the name of the process by which these are transferred to the part labelled as 'X'. (iv) Explain the process of seed formation in a flowering plant. OR (b) (i) Name the type of asexual mode of reproduction shown in the given figure. (ii) Identify the unicellular organism in the diagram. (iii) List any two advantages of asexual reproduction over sexual reproduction. (iv) Name and explain any one mode of asexual reproduction observed in Hydra.

    How the model answer begins

    1. (a)(i) 'X' is the stigma. OR (b)(i) The mode shown is binary fission.

    The full answer from Medha Ma’am →
17. Q17Long answer5 marksAsked: 2025

    (a) (i) Identify the parts 'X' and 'Y' in the figure given below : [figure: flower diagram with labels X, Y, Petal, Sepal] (ii) Name the yellowish coloured structures produced by the part labelled as 'Y'. (iii) Write the name of the process by which these are transferred to the part labelled as 'X'. (iv) Explain the process of seed formation in a flowering plant. OR (b) (i) Name the method of reproduction shown in the diagram given below : [figure: diagrams (a) to (f) showing a unicellular organism] (ii) Identify the unicellular organism in the diagram. (iii) List any two advantages of asexual reproduction over sexual reproduction. (iv) Name any one method of asexual reproduction observed in Hydra and explain it.

    How the model answer begins

    1. (a)(i) X is the stigma and Y is the anther. OR (b)(i), (ii) The diagram shows binary fission, and the unicellular organism is Amoeba.

    The full answer from Medha Ma’am →
18. Q18Long answer5 marksAsked: 2025

    (a) (i) Identify the parts 'X' and 'Y' in the figure given below : [figure of flower showing X, Y, Petal, Sepal] (ii) Write the names of the yellow coloured structures produced by the labelled part 'Y'. (iii) Write the name of the process by which these structures are transferred to the labelled part 'X'. (iv) Explain the process of seed formation in a flowering plant. OR (b) (i) Write the name of the mode of asexual reproduction shown in the figure given below : [figure showing (a) (b) (c) (d) (e) (f)] (ii) Identify the unicellular organism in the figure. (iii) List any two advantages of asexual reproduction over sexual reproduction. (iv) Write the name of one mode of asexual reproduction observed in Hydra and explain it.

    How the model answer begins

    1. (a)(i) X is the stigma and Y is the anther. OR (b)(i) The figure shows binary fission.

    The full answer from Medha Ma’am →
19. Q19Long answer5 marksAsked: 2024

    (a) (i) What are spores ? On which structures are they formed ? How do they overcome unfavourable conditions ? Name the organism which multiplies with the help of these structures. (ii) Give two reasons why some plants are grown by the method of vegetative propagation. List two methods used to grow plants vegetatively. OR (b) (i) Study the diagram given below and name the parts marked as A, B and C. What happens when B reaches C in the ovary ? Mention its significance. (ii) Write the post fertilisation changes that occur in a flower.

    How the model answer begins

    1. (a)(i) Spores are tiny reproductive cells that can develop into new individuals. OR (b)(i) A is the stigma.

    The full answer from Medha Ma’am →
20. Q20Long answer5 marksAsked: 2023

    (a) (i) Where are testes located in the human males and why ? State two function of the testes. (ii) In the human female, one of the ovaries releases an egg every month. State the changes that take place if (1) the egg is fertilized, and (2) the egg is not fertilized. (iii) What is done during the surgical method in males and females to prevent pregnancy ? OR (b) (i) What happens when : (1) Leaves of Bryophyllum fall on the soil ? (2) Planaria is cut into many pieces ? (3) Sporangia of Rhizopus on maturation liberate spores ? Mention the modes of reproduction in each of the above three cases. (ii) Write the changes that occur in a flower once the fertilisation has taken place.

    How the model answer begins

    1. (a) (i) The testes are located outside the abdominal cavity in scrotum. This is because sperm formation requires a lower temperature than the normal body temperature.

    The full answer from Medha Ma’am →

18 more questions of this chapter, each with its model answer, in the AskMedha app.

Objective questions with the board’s key (10)

1. 1. CBSE 2026

   A farmer wants to grow plants with the same genetics as the banana plants already growing in his fields (orchard). Which method would you suggest to achieve this objective :

   • (A) Regeneration
   • (B) Budding
   • (C) Vegetative propagation ✓
   • (D) Sexual reproduction

   Answer: (C)

2. 2. CBSE 2026

   Choose the best statement with reference to Spirogyra, Leishmania and Hydra :

   • (A) They all reproduce sexually.
   • (B) They are unicellular.
   • (C) They are multicellular organisms.
   • (D) They reproduce asexually. ✓

   Answer: (D)

3. 3. CBSE 2026

   The number of chromosomes in parents and offspring of a particular species undergoing sexual reproduction remains constant due to :

   • (A) doubling of chromosomes after zygote formation.
   • (B) halving of chromosomes after zygote formation.
   • (C) doubling of chromosomes before gamete formation.
   • (D) halving of chromosomes at the time of gamete formation. ✓

   Answer: (D)

4. 4. CBSE 2026

   If the part 'P' of the flower is removed, which of the following processes will not take place ?

   • (A) Formation of pollens
   • (B) Formation of flower
   • (C) Formation of fruit ✓
   • (D) Formation of seed

   Answer: (C)

5. 5. CBSE 2026

   Identify the type of reproduction shown in the diagram given below :

   • (A) Budding
   • (B) Fragmentation
   • (C) Spore Formation
   • (D) Binary Fission ✓

   Answer: (D)

6. 6. CBSE 2026

   Spirogyra, despite being a multi-cellular organism, still shows a simple reproductive method. Select the correct option with regard to reproduction in Spirogyra :

   • (A) Asexual reproduction by division of cells into two cells
   • (B) Sexual reproduction by division of cells into many cells
   • (C) Asexual reproduction by breaking up of Spirogyra filaments into smaller parts ✓
   • (D) Sexual reproduction by the formation of gametes after meiosis of cells of filaments followed by fusion of male and female gametes

   Answer: (C)

7. 7. CBSE 2026

   In human beings, the implantation of fertilised egg takes place in which part of female reproductive system ?

   • (A) Oviduct
   • (B) Cervix
   • (C) Uterus ✓
   • (D) Vagina

   Answer: (C)

8. 8. CBSE 2025

   Plants like rose and banana have lost the capacity to produce :

   • (A) flowers
   • (B) buds
   • (C) seeds ✓
   • (D) fruits

   Answer: (C)

9. 9. CBSE 2025

   In a bisexual flower the male gametes are present in the :

   • (A) anther ✓
   • (B) ovary
   • (C) stigma
   • (D) filament

   Answer: (A)

10. 10. CBSE 2025

    Which one of the following has half the number of chromosomes and half the amount of DNA as compared to the non-reproductive body cells?

    • (A) Male germ cell
    • (B) Female germ cell
    • (C) Zygote
    • (D) Both, male and female germ cells ✓

    Answer: (D)

Questions parents and students ask

How many marks does "How do Organisms Reproduce?" carry in CBSE Class 10 Science?

In the CBSE papers of 2023–2026, this chapter carried about 7 marks and about 3 questions a year; by marks it ranks 4 in Science.

Which are the most important (VVI) questions of "How do Organisms Reproduce?"?

The 20 questions above are from the board’s real papers, each with the years it was asked; the most-asked come first with their full model answers. All 38 written questions of this chapter, with answers, are in the AskMedha app.

Do the answers follow the board’s marking scheme?

Yes. CBSE publishes its marking schemes; every model answer here is written point by point to the marks the board’s own scheme gives, and checked by a second, independent model.