ROUTERA


Chapter 1 Reproduction in organisms

Class 12th Biology Chapter Case Study


Case Study 1: Asexual Reproduction in Hydra

Hydra is a small, freshwater organism that exhibits asexual reproduction through budding. In this process, a small outgrowth or bud forms on the body of the parent hydra. The bud grows and eventually detaches from the parent organism, becoming an independent individual. The budding process involves no fertilization, and the offspring is genetically identical to the parent.

Questions:

  1. What type of reproduction is observed in Hydra?

    • A) Sexual reproduction
    • B) Asexual reproduction
    • C) Parthenogenesis
    • D) Regeneration

    Answer: B) Asexual reproduction

  2. What is the result of the budding process in Hydra?

    • A) Formation of gametes
    • B) Formation of new individuals genetically identical to the parent
    • C) Formation of gametes followed by fertilization
    • D) Production of spores

    Answer: B) Formation of new individuals genetically identical to the parent

  3. Which of the following is a characteristic feature of asexual reproduction in Hydra?

    • A) Offspring show genetic variation
    • B) New individuals are formed through a process called budding
    • C) The offspring requires fertilization to develop
    • D) Gametes are involved in the process

    Answer: B) New individuals are formed through a process called budding

  4. Which of the following best describes the offspring produced by asexual reproduction in Hydra?

    • A) Genetically different from the parent
    • B) Genetically identical to the parent
    • C) Requires fertilization to survive
    • D) Only formed during adverse environmental conditions

    Answer: B) Genetically identical to the parent


Case Study 2: Sexual Reproduction in Humans

In humans, sexual reproduction involves the fusion of male and female gametes (sperm and egg) during fertilization. The male gamete (sperm) is produced in the testes, while the female gamete (egg) is produced in the ovaries. Upon fertilization, a zygote is formed, which develops into an embryo. This process occurs in the female reproductive system.

Questions:

  1. What is the name of the process by which the male and female gametes fuse?

    • A) Meiosis
    • B) Fertilization
    • C) Mitosis
    • D) Budding

    Answer: B) Fertilization

  2. Where are the male and female gametes produced in humans?

    • A) Sperm in the ovaries, egg in the testes
    • B) Both sperm and egg in the testes
    • C) Sperm in the testes, egg in the ovaries
    • D) Both sperm and egg in the uterus

    Answer: C) Sperm in the testes, egg in the ovaries

  3. What is formed when the sperm and egg fuse during fertilization?

    • A) A zygote
    • B) A gamete
    • C) An embryo
    • D) A fetus

    Answer: A) A zygote

  4. Which of the following is true about human sexual reproduction?

    • A) Only the female gamete is required for fertilization
    • B) Sexual reproduction involves the fusion of haploid gametes
    • C) The offspring produced is genetically identical to the parent
    • D) Male gametes are produced by mitosis

    Answer: B) Sexual reproduction involves the fusion of haploid gametes


Case Study 3: Vegetative Propagation in Plants

Vegetative propagation is a form of asexual reproduction in plants, where new plants are produced from vegetative parts like roots, stems, or leaves. For example, in potatoes, new plants are formed from eyes (buds) present on the tuber. Similarly, in strawberries, new plants grow from the runners (stems that grow along the ground).

Questions:

  1. What is vegetative propagation in plants?

    • A) A type of sexual reproduction
    • B) A type of asexual reproduction
    • C) A process of seed formation
    • D) A method of pollination

    Answer: B) A type of asexual reproduction

  2. Which part of the potato is responsible for vegetative propagation?

    • A) Flower
    • B) Leaf
    • C) Tuber (eyes)
    • D) Root

    Answer: C) Tuber (eyes)

  3. Which of the following is an example of vegetative propagation in strawberries?

    • A) Seeds
    • B) Runners
    • C) Flowers
    • D) Tubers

    Answer: B) Runners

  4. What is the main characteristic of offspring produced by vegetative propagation in plants?

    • A) They are genetically different from the parent plant
    • B) They are genetically identical to the parent plant
    • C) They require fertilization to grow
    • D) They grow only during certain seasons

    Answer: B) They are genetically identical to the parent plant


Case Study 4: External Fertilization in Fish

In many aquatic animals like fish, external fertilization occurs. During the breeding season, the female releases her eggs into the water, and the male releases sperm over the eggs. Fertilization occurs outside the female’s body in the water, and the fertilized eggs develop into larvae.

Questions:

  1. Where does fertilization occur in fish?

    • A) Inside the female’s body
    • B) Inside the male’s body
    • C) Outside the female’s body, in water
    • D) In the uterus

    Answer: C) Outside the female’s body, in water

  2. What is the main advantage of external fertilization in aquatic organisms like fish?

    • A) High protection for the fertilized eggs
    • B) Large number of offspring produced
    • C) Fertilization occurs inside the female’s body
    • D) Involves no gametes

    Answer: B) Large number of offspring produced

  3. Which of the following is a characteristic of external fertilization?

    • A) Offspring are protected in the mother’s body
    • B) A smaller number of offspring are produced
    • C) Both eggs and sperm are released into the environment
    • D) Fertilization takes place inside the female reproductive tract

    Answer: C) Both eggs and sperm are released into the environment

  4. What type of environment is essential for external fertilization to occur?

    • A) Dry land
    • B) Warm water
    • C) Moist conditions
    • D) Aquatic environment

    Answer: D) Aquatic environment


Case Study 5: Parthenogenesis in Honeybees

In honeybees, parthenogenesis is a form of asexual reproduction in which unfertilized eggs develop into male bees (drones). Fertilized eggs develop into female bees (workers and queens). Parthenogenesis occurs naturally in bees, where males are produced from unfertilized eggs, and females arise from fertilized eggs.

Questions:

  1. What is parthenogenesis?

    • A) Reproduction involving fertilization
    • B) Development of an offspring from an unfertilized egg
    • C) Reproduction through budding
    • D) Fusion of two gametes from different individuals

    Answer: B) Development of an offspring from an unfertilized egg

  2. In honeybees, what do unfertilized eggs develop into?

    • A) Worker bees
    • B) Queen bees
    • C) Male bees (drones)
    • D) Female bees

    Answer: C) Male bees (drones)

  3. What type of fertilization occurs in honeybees to produce female offspring?

    • A) Internal fertilization
    • B) External fertilization
    • C) No fertilization
    • D) Both fertilized and unfertilized eggs

    Answer: D) Both fertilized and unfertilized eggs

  4. Which of the following statements is true about parthenogenesis in honeybees?

    • A) Only males are produced through parthenogenesis
    • B) Both males and females are produced through parthenogenesis
    • C) Fertilization is required to produce both males and females
    • D) Parthenogenesis does not occur in honeybees

    Answer: A) Only males are produced through parthenogenesis