Diversity In Living Organisms Class 9 CBSE Notes - Chapter 7

There are a variety of factors such as geographic, biotic, abiotic that affect the diversity in living organisms. For instance, the earliest known ancestors of whales (not direct) were similar to today’s dogs. But over the course of many aeons, limbs transformed to flippers and fins, size increased drastically, resulting in the evolution of whales as we know them today.

What is the Basis of Classification?

Humans have been trying to classify living organism based on mutual or related characteristics since the days of Aristotle. For instance, everything that resembled plants, like lichen, were thought to belong to the plant kingdom. Today, however, there are more factors at play when classifying organisms. These range from the type of cell, whether it has a nucleus or not, single cellular, unicellular, ability to perform photosynthesis etc.

Classification and Evolution

The body plans that various organisms that we see today are essentially the result of aeons of evolution. For instance, Tetrapodophis was an extinct snake that lived over 120 million years ago. It is also one of the oldest snakes to have ever been discovered. However, the reason that this specimen is significant is that it has four limbs. Therefore, this was a kind of “transitionary” animal between limbed and limbless snakes like the one we see today.

Diversity In Living Organisms Class 9 Notes – Questions

  1. State the reasons why we classify life.
  2. State one example of the range of variations in lifeforms.
  3. State the criteria for classification under Kingdom Monera.
  4. What are angiosperms? How are they different from gymnosperms?
  5. On what basis are organisms grouped into the 5 kingdoms?

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Air can be regarded as: