Question 3
Sexual Reproduction and Vegetative Propagation
| Sl. No. | Sexual Reproduction | Vegetative Propagation |
|---|---|---|
| 1. | Reproduction in flowering plants which involves fusion of male and female gametes and seed formation. | Reproduction in some flowering plants, in which new plants arise from a vegetative part such as root, stem or leaf etc. |
| 2. | The offspring shows variation. | Offspring is identical to the parent. |
| 3. | Seed is formed and gives rise to a new plant | Plant parts like tuber, rhizome, corm, stem, root, leaves etc. are used to grow new plants. |
Reproduction in Animals – Interactive Study Guide
Reproduction ensures the continuation of species. Animals reproduce sexually (fusion of gametes) or asexually (single parent, no gametes). This chapter also covers embryo development and cloning.
Sexual vs Asexual Reproduction
| Feature | Sexual | Asexual |
|---|---|---|
| Parents | Two (male + female) | One |
| Gametes | Required (sperm + egg) | Not required |
| Offspring | Genetically different (variation) | Genetically identical (clones) |
| Examples | Humans, frogs, birds | Amoeba, Hydra, yeast |
Fertilisation Types
Inside female body. Fewer eggs, better protection. Examples: humans, birds, dogs.
Outside body (in water). Many eggs, lower survival. Examples: frogs, fish, starfish.
Development Sequence
Zygote (1 cell) divides → Embryo (ball of cells, implants in uterus) → Foetus (recognisable body parts) → Birth (~9 months in humans)
Nutrition via placenta through umbilical cord.
Asexual Reproduction Types
- Budding: Bud grows from parent → detaches (Hydra, yeast)
- Binary fission: Parent splits into 2 equal parts (Amoeba, bacteria)
- Fragmentation: Body breaks into fragments, each grows (Planaria, starfish)
Cloning: Dolly the Sheep
First cloned mammal (1996). Ian Wilmut, Roslin Institute, Scotland. Nucleus from donor cell → enucleated egg → embryo → surrogate mother → Dolly (genetic copy of donor).
Self-Test Questions
- What is the difference between internal and external fertilisation?
- Differentiate between viviparous and oviparous animals with examples.
- Describe binary fission in Amoeba.
- What is IVF? Why is it called "test-tube baby"?
- How was Dolly the sheep cloned?