Natural Resources — Science STD 9 — Question

Define the terms and given one example:

Bilateral symmetry.

What happens to the passengers travelling in a bus when the bus takes a sharp turn? Give reasons for your answer.

There are two types of forces X and Y. The forces belonging to type X can produce motion in a stationary object but cannot change the shape of the object. On the other hand, forces belonging to type Y cannot produce motion in a stationary object but can change the shape of the object. What is the general name of the forces such as (a) X, and (b) Y?

What is relation between division of labour and various types of tissues?

Name two most popular marine fishes.

Name two gases of air which dissolve in water by diffusion. What is the importance of this process in nature?

Why will a sheet of paper fall slower than one that is crumpled into a ball?

What is cyton?

Explain the following giving examples.
Pure substance.

A force of 20N acts upon a body whose weight is 9.8N. What is the mass of the body and how much is its acceleration? (g = 9.8ms^-2).