Q12 of 36 Page 1

Explain how ozone being a deadly poison can still perform an essential function for our environment.

OR


Give reason why a food chain cannot have more than four trophic levels.


The ozone layer is harmful because it is a mixture of 3 oxygen atoms that make it highly reactive, which is not good for our body system, and it is necessary because it protects the earth's surface from the sun 's entry of UV rays that can damage us by causing skin burning and skin cancer.


OR


The loss of energy at each step is so great that very little usable energy remains after four trophic levels.


More from this chapter

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10

Veins are thin walled and have valves. Justify

 11

How is the wall of the small intestine adapted for performing the function of absorption of food?

OR


Out of a goat and a tiger, which one will have a longer small intestine? Justify your answer.


 13

State the role of pancreas in digestion of food.

 14

For question numbers 14, 15 and 16, two statements are given- one labeled Assertion (A) and the other labeled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:

Assertion: After white washing the walls, a shiny white finish on walls is obtained after two to three days.


Reason: Calcium Oxide reacts with Carbon dioxide to form Calcium Hydrogen Carbonate which gives shiny white finish.


a) Both A and R are true, and R is correct explanation of the assertion.


b) Both A and R are true, but R is not the correct explanation of the assertion.


c) A is true, but R is false.


d) A is false, but R is true.