Q21 of 33 Page 1

(a) What do you understand by “Watershed Management”? List any two advantages of watershed management.

(b) “Human beings occupy the top level in any food chain.” What are the consequences of this on our body?

(a) Scientific conservation of soil and water to increase biomass production is called watershed management.


Advantages of watershed management are: [ any 2]


i. It enhances the life of downstream dam and reservoirs.


ii. It minimizes the risk of droughts, landslides and floods.


iii. It increases ground water level


iv. It increases crop production


v. Various developmental activities like hydroelectric power generation, supply water for irrigation and other domestic uses.


(b) The concentration of chemicals goes on increasing at different trophic levels. It is maximum at higher trophic levels since human beings occupy the top level in a food chain so there is maximum concentration of toxic substances in our body i.e. biomagnification level is maximum. And according to 10% law very less amount of energy is available to humans.


More from this chapter

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20

a) What is reactivity series? How does the reactivity series of metals help in predicting the relative activities of various metals?

b) Suggest different chemical processes used for obtaining a metal from its oxides of metals in the middle of the reactivity series and metals towards the top of the reactivity series. Support your answer with one example each.

 21

(a) “Improvements in our lifestyle have resulted in greater amounts of waste generation.” Give two examples to support the given statement. Suggest one change that we can incorporate in our lifestyle in order to reduce nonbiodegradable waste.

(b) The following organisms form a food chain. Insect, Hawk, Grass, Snake, Frog Which of these will have highest concentration of non-biodegradable chemicals? Name the phenomenon.

 22

What do you observe when you drop a few drops of acetic acid to a test tube containing:

a) Phenolphthalein


b) Universal indicator


c) distilled water


d) sodium hydrogen carbonate.

 23

Riya performs two set of experiments to study the length of the foam formed which are as follows:

Set I: she takes 10 ml of distilled water in a test tube “A” and adds 5-6 drops of liquid soap in it and shakes the test tube vigorously.


Set II: she takes 10 ml of distilled water in a test tube “A” and adds 5-6 drops of liquid soap with half spoonful of CaSO4 in it and shakes the test tube. Write your observation and reason.