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Case study on reproduction

This type of question, asked 4 times: 2022, 2023, 2024, 2025. All 5 questions below, oldest first.

Try each one first, then open its answer.

  1. Question 1 (case study, 4 parts)

    2022

    The modes by which various organisms reproduce depend on the body design of the organisms. In asexual reproduction, a single individual parent produces offsprings without the involvement of gametes. This method is a common means of increasing the offsprings rapidly under favourable conditions. Asexual reproduction occurs mostly in unicellular organisms, some plants and certain simple multicellular animals.
    15 (a)
    State the name of the organism in which binary fission takes place in a definite orientation. Also name the disease caused by this organism.
    15 (b)
    List any two advantages of producing plants through vegetative propagation.
    15 (c) (i)
    Explain the process of budding in Hydra.
    15 (c) (ii)
    What happens when (I) a spirogyra filament matures and attains a considerable length, and (II) a sporangia in Rhizopus bursts on maturation ?

  2. Question 2 (case study, 4 parts)

    2023

    All the reproductive methods of living organisms are broadly categorized into two types : 1. Asexual reproduction, and 2. Sexual reproduction. Asexual reproduction involves the participation of a single parent without the formation of gametes, fertilisation and transfer of genetic material. This method is a common means of rapidly increasing offsprings under favourable conditions.
    38 (a)
    Name the type of fission that occurs in Leishmania and Plasmodium.
    38 (b)
    Write one advantage of sexual mode of reproduction over asexual reproduction.
    38 (c)
    Give reasons why : (i) Colonies of yeast fail to multiply in water but multiply in sugar solution. (ii) Rhizopus individuals do not grow on a dry slice of bread.
    38 (c) OR
    Name the filamentous structures a student could identify when he collected water from a pond that appeared dark green. How do these organisms multiply ? Explain.

  3. Question 3 (case study, 4 parts)

    2024

    Asexual reproduction involves a single parent to produce offsprings without the formation of gametes. It occurs by the following ways : Fission, Budding, Fragmentation, Spore formation and Regeneration. In one of the methods like regeneration, Planaria A is cut horizontally into three pieces – L, M and N and Planaria B is cut vertically into two equal halves – O and P.
    38 (a)
    Which of the cut pieces of the two Planaria could regenerate to form a complete organism ?
    38 (b)
    Give an example of another organism which follows the same mode of reproduction as Planaria.
    38 (c)
    What is the meaning of ‘development’ in regeneration ?
    38 (c) OR
    Differentiate between regeneration and fragmentation.

  4. Question 4 (case study, 4 parts)

    2024

    Pollination is an important process in sexual reproduction of plants. It is an essential process that facilitates fertilisation in plants. Pollinating agents can be wind, water, insects and birds. Several changes take place in the flower after the fertilization has taken place.
    38 (a)
    Write the main difference between self-pollination and cross-pollination.
    38 (b)
    Name the part of the flower which attracts insects for pollination. What happens to this part after fertilisation ?
    38 (c) (i)
    Define fertilisation. What is the fate of ovules and the ovary in a flower after fertilisation ?
    38 (c) (ii)
    In a germinating seed, which parts are known as future shoot and future root ? Mention the function of cotyledon.

  5. Question 5 (case study, 4 parts)

    2025

    When a girl is born, the ovaries already contain thousands of immature eggs. On reaching puberty, some of these start maturing. One matured egg is released every month by one of the ovaries. The two oviducts unite into an elastic bag-like structure known as uterus.
    38 (a)
    Write the site of fertilization in human female.
    38 (b)
    How does the uterus prepare itself to receive and nurture the growing embryo ? Explain.
    38 (c) (i)
    What happens when the egg is not fertilized ?
    38 (c) (ii)
    How does the developing embryo get nutrition from the mother’s blood ? Explain.