Tag: effect of water pollution

Questions Related to effect of water pollution

BOD is ___________ in polluted water and ________in potable water.

biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

  1. more, less

  2. less, more

  3. less in both

  4. medium in both

Show answer
Correct Option: A
Explanation:
A low BOD is an  indicator of good quality of water. Whereas a high BOD indicates polluted water as in that water the dissolved oxygen is consumed by bacteria.
So, the correct option is 'more, less'

BOD of wastewater is amount of

biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

  1. total organic matter

  2. biodegradable organic matter

  3. oxygen evolution

  4. oxygen consumption

Show answer
Correct Option: D
Explanation:

biological oxygen demand is the amount of Oxygen required by aerobic micro-organisms for the breakdown of organic matter present in waste water or polluted water.

So, the correct answer is 'oxygen consumption'

Measurement of the rate of oxygen consumption in unit volume of water over a period of time is done to find out

biology natural resources and agriculture effects of water pollution effect of water pollution water pollution and its control

  1. Biogas generation

  2. Biological oxygen demand

  3. Biosynthetic pathways

  4. Fermentation

Show answer
Correct Option: B
Explanation:

Decomposition of organic matter by microbes requires oxygen. Degree of impurity of water due to organic matter is measured in terms of 'Biological Oxygen Demand (BOD)'. BOD is the oxygen in milligrams required for 5 days in 1 litre of water at 20 degree centigrades for the microorganisms to metabolise organic wastes.

Biological Oxygen Demand (BOD) is a measure of

biology natural resources and agriculture effects of water pollution effect of water pollution water pollution and its control

  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.

Show answer
Correct Option: B
Explanation:

Decomposition of organic matter by microbes requires oxygen. Degree of impurity of water due to organic matter is measured in terms of Biochemical oxygen demand or (BOD). BOD is the oxygen required by microorganisms to completely metabolise organic wastes present in water.

Huge quantity of sewage is dumped in a river. The BOD will.

biology natural resources and agriculture effects of water pollution effect of water pollution water pollution and its control

  1. Increase

  2. Decrease

  3. Slightly decrease

  4. Remain unchanged

Show answer
Correct Option: A
Explanation:

A huge quantity of sewage increases Organic matter in the river water.

The oxygen demand by bacteria to degrade the organic matter increases.
The biological oxygen demand increases.
So, the correct option is 'Increase'.

Biochemical oxygen demand measures

biology natural resources and agriculture effects of water pollution effect of water pollution water pollution and its control

  1. Industrial pollution

  2. Air pollution

  3. Dissolved oxygen required for decomposers

  4. Pollution capacity of effluents

Show answer
Correct Option: C
Explanation:
Biochemical oxygen demand or BOD is the amount of oxygen required to decompose organic matter in one litre of polluted water.
If the water is more polluted, more will be the BOD because more will be the organic matter present in it and hence, more oxygen will be required to decompose it.
So, BOD measures the amount of dissolved oxygen required for decomposers to decompose the organic matter in the water.
So, the correct answer is 'Dissolved oxygen required for decomposers'.

Multiple Choice Questions
Biochemical oxygen demand may not be good index for water bodies receiving effluents from.

biology natural resources and agriculture effects of water pollution effect of water pollution water pollution and its control

  1. Sugar industry

  2. Domestic sewage

  3. Dairy industry

  4. Petroleum industry

Show answer
Correct Option: D
Explanation:

Biochemical Oxygen Demand or BOD is the amount of dissolved oxygen in a water body, required by microorganisms for the aerobic breakdown of organic matter in the water. Petroleum waste consists of inorganic constituents that also may cut off the oxygen supply into the water body thus BOD may not be a good index for water receiving effluents containing it.

So, the correct option is 'petroleum industry'.

If a water body have high amount of DDT it's 'Biochemical Oxygen Demand' (B.O.D.) will

biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

  1. Decrease

  2. Not affected

  3. Increase

  4. First decrease than increase

Show answer
Correct Option: C
Explanation:

Biological Oxygen Demand (BOD) is one of the most common measures of pollutant organic material in water. BOD indicates the amount of putrescible organic matter present in water. Therefore, a low BOD is an indicator of good quality water, while a high BOD indicates polluted water. When BOD levels are high, dissolved oxygen (DO) levels decrease because the oxygen that is available in the water is being consumed by the bacteria. Since less dissolved oxygen is available in the water, fish and other aquatic organisms may not survive.


So, the correct option is 'Increase'.

The enhanced growth of water hyacinth in lakes can be due to

biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

  1. Disposal of solid wastes in water bodies

  2. Availability of more nutrients to the flora of a water ecosystem

  3. Discharge of sewage into water bodies

  4. All of the above

Show answer
Correct Option: D
Explanation:

Water hyacinth (Eichhornia crassipes) also known as Bengal terror is waterweed often blamed for choking water bodies and creating problems for aquatic plants and animal due to less availability of oxygen. It mainly grows where organic nutrient is present in large amount. Level of the nutrient increase due to use of pesticide, weedicides, of discharge of sewage into the water bodies. 

So, the correct option is 'all of the above'.

BOD of lake becomes high by :-

biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

  1. Vehicles

  2. Wind mill

  3. Smoke and ammonia

  4. Detergents

Show answer
Correct Option: D
Explanation:
BOD or biological oxygen demand is the amount of water needed by aerobic organisms to break down the organic substances (waste substances) present in a water body. Detergents reduce the amount of oxygen in a water body. This may result in an increase in the BOD. It may also result in an increase in eutrophication in the water bodies. Vehicles, wind mill, and smoke and ammonia on the other hand act mostly as air pollutants and are responsible for air pollution.
So, the correct answer is 'Detergents'.