Basis Of Classification
Chapter Name : Animal Kingdom |
Sub Topic Code : 103_11_04_01_02 |
Topic Name : Basis Of Classification |
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Sub Topic Name : Symmetry |
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Introduction
Symmetry is defined on the basis of the ability to divide the body of an organism into equal halves.
Pre-Requisites:
The levels of organization of animals.
Activity:
Observe some organisms under the microscope or by naked eye. Try to spot the central axis and divide the organism into two equal halves.
Real Life Question:
Can our body be divided into 2 equal halves?
Key Words / FlashCards
| Key Words | Definitions (pref. in our own words) |
|---|---|
| Asymmetrical Bilateral symmetry Radial symmetry | any plane that passes through the centre does not divide the body of the organism into equal halves body can be divided into identical left and right halves in only one plane any plane passing through the central axis of the body divides the organism into two identical halves |
Learning aids / Gadgets
| Gadgets | How it can be used |
|---|---|
| See some examples of each type of symmetry in your book, then try to relate the type of symmetry with other organisms | Understanding that every organism cannot be divided into equal halves. |
Places to visit :
Biology Laboratory
Practical examples around us
| Examples | Explainations |
|---|---|
| Body of human beings can be divided into two equal halves only in one plane, hence humans have bilateral symmetry. |
What you learn in Theory:
The different types of symmetries and the organisms that display those.
What you learn in Practice:
Humans display bilateral whereas hydra displays radial symmetry. But there can be organisms that show no symmetry at all, like sponges.