Question

Grade 9, Diversity in Living Organisms.

1) Why is it difficult to classify Bacteria? [2 points]

2) Why was the method of classification of animals given by Aristotle not accepted?

3) What is a notochord? Explain its functions.

30 pts.

Answer 1

1) Bacteria are one of the largest groups of species so it is very difficult to classify them.

$They \: mainly \: belong \: to \: five \: classes$

•Monera

•Protista

•Plantae

•Fungi

•Animalia

Kingdom Monera is divided into Eubacteria and Archaebacteria.

2) Aristotle had made an attempt to classify organisms according to whether they lived on land, water and air.

This classification was not accepted because it was based on very few criterias, even though this was very simple , but misleading.

One of the major drawback of this classification was that this could not reflect natural relationships of organisms.

As a result, different types of organisms were grouped together.

For example- Animals that live in the sea include corals, whales, octopuses, starfish and sharks.

We can immediately see that these are very different from each other in numerous ways.

In fact, their habitat is the only point they share in common.

This is not an appropriate way of making groups of organisms to study and think about.

3) Notochord is a rod like structure running at the back of the body separating the nervous system from the alimentary canal.

$Functions$

•It mainly supports the body.

•It provides a place for the muscles to get attached to help in movement.

Answer 2

YOUR ANSWER :

________

ans 1)

all bacteria looks almost the same and also they are huge in number..so

its very difficult to classify them and to know about each one of them separately.

____________

ans 2)

Aristotle  thought that he should classify animals on the basis of

the habitat  live in.but the problem they arose was that these animals were now different in many respect so it was not proved much helpful so..it was not accepted

____________

ans 3)

notochord is a long , flexible and  as well as rod like structure present in all

chordates.

• usually present in embryo  of the chordates.

main fuctions is to support the embryo growth which develops and usually become part of vertebral column.

__________