Tag: human influences on the environment

Questions Related to human influences on the environment

Limit of B.O.D. prescribed by Central Pollution Control Board for the discharge of industrial and municipal waste waters into natural surface waters, is 

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

  1. < 30 ppm

  2. < 3.0 ppm

  3. < 10 ppm

  4. < 100 ppm

Show answer
Correct Option: C
Explanation:

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. The central pollution control board prescribed the BOD limit for the discharge of industrial and municipal waste water as < 10ppm

So, the correct answer is '< 10 ppm'

In a survey conducted in Delhi, on the efforts being made to clear the Km patch in Yamuna, it was observed that the BOD in 2003 was 13 mg/litre while it was 18 mg/litre in 2004. 
What inference can you draw from the following data?
biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

  1. The pollutants in the river has decreased due to efforts by Delhi government.

  2. Despite efforts there are still dissolved minerals in the river.

  3. Although efforts are being made, the pollution is still on an increase in Delhi.

  4. There is an algae in the river.

Show answer
Correct Option: C
Explanation:

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. As the level of BOD increases, this shows that efforts are being made to clean Yamuna river but pollution is still on an increase in Delhi. 

Therefore, the correct answer is option C.

Increase of BOD in water leads to

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

  1. Increase in the dissolved oxygen concentration

  2. Decrease in the dissolved oxygen concentration

  3. Maintenance of dissolved oxygen concentration at the same level

  4. No effect on dissolved oxygen concentration

Show answer
Correct Option: B
Explanation:

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. Domestic sewage primarily contains biodegradable organic matter, which readily decomposes by micro-organisms, which can multiply using these organic substances as substrates and hence utilise some of the components of sewage. It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring biochemical oxygen demand (BOD). Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures. 

Sewage drainage into water bodies is harmful for fishes because

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

  1. Excessive CO$ _2$ is added in water.

  2. It gives off a bad smell.

  3. It removes the competition with fishes to dissolved oxygen.

  4. It increase competition of fishes for dissolved oxygen.

Show answer
Correct Option: D
Explanation:

Domestic sewage primarily contains biodegradable organic matter, which readily decomposes by bacteria and other micro-organisms, which can multiply using these organic substances as substrates and hence utilise some of the components of sewage. It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring biochemical oxygen demand (BOD). Micro-organisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures. 

In a sewage plant, BOD is indicated as high. After sometime it shows a decrease then

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

  1. There is increase in bacterial growth but decrease in oxygen.

  2. There is decrease in bacterial growth but increase in oxygen.

  3. There is increase in bacterial growth but increase in oxygen.

  4. There is decrease in bacterial growth but decrease in oxygen.

Show answer
Correct Option: B
Explanation:

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. BOD can be used as a gauge of the effectiveness of wastewater treatment plants. It is listed as a conventional pollutant in the U.S. Clean Water Act.

Higher the BOD, more is the pollution.
Thus, if BOD had reduced, it shows decrease in bacterial growth which consumes the oxygen present and ensures increase in oxygen level.
Therefore, the correct answer is option B.

When domestic sewage mixes with river water 

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

  1. Small animals like rats will die after drinking river water.

  2. The increased microbial activity release micro nutrients, such as iron.

  3. The increased microbial activity uses up dissolved oxygen.

  4. The river water is still suitable for drinking as impurities are only about 0.1%.

Show answer
Correct Option: C
Explanation:

Domestic sewage primarily contains biodegradable organic matter, which readily decomposes by bacteria and other microorganisms, which can multiply using these organic substances as substrates and hence, utilise some of the components of sewage. It is possible to estimate the amount of biodegradable organic matter in sewage water by measuring biochemical oxygen demand (BOD). Microorganisms involved in biodegradation of organic matter in the receiving water body consume a lot of oxygen, and as a result there is a sharp decline in dissolved oxygen downstream from the point of sewage discharge. This causes mortality of fish and other aquatic creatures. 

High BOD indicates

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

  1. Highly polluted $H _2O$

  2. Less pollution in $H _2O$

  3. Less sewage

  4. Less microorganism

Show answer
Correct Option: A
Explanation:

Biological oxygen demand (BOD) is the rate at which microorganisms in water take up oxygen. A high BOD indicates two things - there is a high level of microorganisms in the water and there is a high content of organic material in the water that is broken down by the organisms. This is an indication of organic pollution.

BOD (biological oxygen demand) is

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

  1. Amount of oxygen consumed by microorganisms for decaying organic matter per unit volume of water

  2. Amount of CO consumed by microorganisms per unit of sewage water

  3. Amount of oxygen required by aquatic plants for survival

  4. None of the above

Show answer
Correct Option: A
Explanation:

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. Biochemical oxygen demand is the amount of oxygen required for microbial metabolism of organic compounds in water.

Which one of the following statement is true?

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

  1. The greater the BOD of waste water, more is its polluting potential.

  2. The greater the BOD of waste water, less is its polluting potential.

  3. The lesser the BOD of waste water, more is its polluting potential.

  4. None of the above.

Show answer
Correct Option: A
Explanation:

BOD(Biochemical Oxygen Demand) which is defined as amount of dissolved oxygen needed by aerobic biological organisms to break down organic material present in a given water sample at certain temperature over a specific time period. Therefore, the greater the BOD of waste water, more is its polluting potential. 

Therefore, the correct answer is option A.

Biological Oxygen Demand (BOD) is a measure of 

biology human influences on the environment 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 compound

  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:

Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. It is used as a measure of the degree of water pollution. 

Therefore, the correct answer is option B.