Effect of Sewage on Water Bodies

Q.

What is Biological Oxygen Demand (BOD)?

Q. The high value of BOD (Biochemical Oxygen Demand) indicates that:

1. Consumption of organic matter in the water is higher by the microbes
2. Water is pure
3. Water is highly polluted
4. Water is less polluted

Q.

Explain some harmful effects of agricultural practices on the environment?

Q. Which of the following represent the sedimentary type of nutrient cycle?

1. Nitrogen
2. Carbon
3. Phosphorus
4. Oxygen

Q.

Question 16

Polluted water bodies have usually very high abundance of plants like Nostoc and Oscillitoria. Give reasons.

Q.

What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.

Q.

Give reasons for the following:
Farmers prefer to grow beans and peas in nitrogen deficient soils.

Q.

What are the various constituents of domestic sewage? Discuss the effects of sewage discharge on a river.

Q. Which of the following facilitates increased oxygen transfer in a sparged stirred-tank bioreactor?

1. Bubbles
2. Turbidity
3. Cells
4. Proteins

Q.

All the following are waterborne diseases except

1. Typhoid

2. Amoebiasis

3. Dysentery

4. cancer

Q. Which of the following statements regarding eutrophication are correct ?
(i) Eutrophication is the natural ageing of a lake by nutrient enrichment of its water.
(ii) Pollutants from human activities like effluents from the industries and homes can radically accelerate the aging process of a lake. This phenomenon is called as cultural or accelerated eutrophication.
(iii) The plant nutrients responsible for eutrophication are nitrates and phosphates.
(iv) These phosphates and nitrates accelerate the growth of algae, which utilise oxygen and may deoxygenate the water to kill the fish and other aquatic animals.

1. (i) and (ii)
2. (iii) and (iv)
3. (i), (ii) and (iii)
4. (i), (ii), (iii) and (iv)

Q.

What is the use of carbon dioxide for marine animals?

Q. Assertion : Eutrophication shows increase in productivity in water.

Reason : With increasing eutrophication, the diversity of the phytoplankton increases.

1. If both assertion and reason are true and reason is the correct explanation of assertion
2. If both assertion and reason are true but reason is not the correct explanation of assertion
3. If assertion is true but reason is false
4. If both assertion and reason are false

Q. State whether true or false:
Coliform bacteria are found in the small intestine of humans.

1. True
2. False

Q. Explain the effect on the characteristics of a river when urban sewage is discharged into it. [3]

Q. 'Biological Oxygen Demand' (BOD) is a measure of

1. Industrial wastes poured into water bodies
2. Extent to which water is polluted with organic compounds
3. Amount of carbon monoxide inseparably combined with haemoglobin
4. Amount of oxygen needed by green plants during night

Q. Observe figure and answer the following questions.



i. What ecological term is used to describe the DDT accumulation at different trophic levels?
ii. List any one effect of DDT accumulation on birds.
iii. Will DDT accumulation lead to eutrophication?
iv. Does it affect the BOD?
v. Name disease caused by accumulation of any heavy metal.

Q. The minimum number of chromosomes in plants is

1. 2n = 16
2. 2n = 4
3. 2n = 14
4. 2n = 2

Q.

Is algae harmful?

Q. With the rise in water termperature, dissolved oxygen

1. remains unchanged
2. increases in amount
3. decreases in amount
4. is more available to the aquatic organisms

Q.

Briefly describe four abiotic factors found in an ecosystem.

Q. Foul smell in water bodies like tanks and ponds is due to

1. Aerobiosis
2. Anaerobiosis
3. Psammophytes
4. Biological magnification

Q.

What are the main causes of algal blooms?

Q.

Write one negative effect on the environment of affluent life style of few persons of a society.

Q. Select the option that includes a pair of biofertilisers

1. Azotobacter and BGA
2. Nostoc and E.coli
3. Rhizobium and Salmonella
4. Salmonella typhi and E.coli

Q. Sedimentary cycle having a small gaseous component is found in :

1. Phosphorus
2. Nitrogen
3. Carbon
4. Sulphur

Q.

Explain “ water hyacinth is terror of Bengal”.

Q.

Does sulphur water kill fish?

Q. Explain some harmful effects of agricultural practices on the environment.

Q.

Is water hyacinth a floating plant?