Draw neat and labelled diagrams of a sperm and ovum. Answer the following questions:
(a) Is a sperm and an ovum unicellular or multicellular ?
(b) Name the organ of the human body where these gametes are produced.
(c) Name the process of the fusion of these gametes.
(d) Name the organ where the fusion of these gametes take place.
(e) What is formed by the fusion of the sperm and ovum ?
Labelled diagrams of a sperm and ovum are shown below:
Sperm
Ovum
(a) A sperm and an ovum are unicellular.
(b) In males, the testes produce male gametes (sperms), and in females, the ovaries produce female gametes (eggs).
(c) Fertilisation.
(d) The fusion of male and female gametes in humans takes place in the fallopian tube.
(e) Zygote is formed by the fusion of the sperm and ovum.
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?