Class 12, Zoology PPT - 1. Reproduction in Organisms

Class 12, Zoology PPT | Chapter 1. Reproduction in Organisms

Chapter Outline

1.1. Modes of reproduction

1.2. Asexual reproduction

1.3. Sexual reproduction

Learning Objectives

➢ Learns the modes of asexual reproduction in organisms.

➢ Understands the significance of asexual

reproduction.

➢ Comprehends the different modes of

sexual reproduction.

➢ Realizes the significance and advantage of sexual reproduction and its role in evolution.

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Reproduction in Animals – Quik Hints

1. Asexual Reproduction

- one parent is needed.

- Gametes are not part of this process.

- Fertilization does not happen.

- Offspring are usually very similar to the parent.

- Common methods are: Binary fission, budding, fragmentation and regeneration.

- Examples include Amoeba, which uses binary fission and Hydra, which uses budding.

Asexual Reproduction fascinating because it shows how life can duplicate itself without a partner.

2. Sexual Reproduction

- Usually two parents are involved.

- Male and female gametes are produced.

- Fertilization creates a zygote.

- Offspring show variation.

- Examples are humans, frogs and mammals.

Sexual Reproduction amazing as it creates diversity and keeps species evolving.

3. Parthenogenesis

- A new individual develops from an egg that has not been fertilized.

- Fertilization does not occur in this case.

- This process is seen in some animals such as honeybees, aphids and certain reptiles.

- In honeybees male drones come from eggs while female bees come from fertilized eggs.

Parthenogenesis is a shortcut that some species use to reproduce when mates are scarce.