Tag: human influences on the environment

Questions Related to human influences on the environment

Which of the option shows following examples in ascending order in terms of BOD?
(i) Distilled water (ii) Tap water(iii) Sewage wastes drained in river

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

  1. ii- i- iii

  2. i- ii- iii

  3. iii- i- ii

  4. iii- ii- i

Show answer
Correct Option: B
Explanation:

BOD is the oxygen required by microorganisms to metabolise organic wastes in the water. Biological treatment of wastewater will reduce the organic impurities or an organic load of polluted water, thus curtail the level of BOD. The greater the content of organic waste in the water greater will be the BOD. Organic waste will be maximum in the sewage waste. Hence it will have the highest BOD. Thus the correct answer is option B.

Study the lists and find the correct match.

I II
(a) BOD (i) Treatment of sewage
(b) KVIC (ii) Measure of organic matter in water
(c) LAB (iii) Biological methods for controlling plant diseases
(d) STPS (iv) Increases vitamin B$ _{12}$
(v) Production of biogas
biology human influences on the environment effects of water pollution effect of water pollution water pollution and its control

  1. a-iv, b-iii, c-ii, d-v

  2. a-v, b-ii, c-iii, d-i

  3. a-ii, b-i, c-iv, d-v

  4. a-ii, b-v, c-iv, d-i

Show answer
Correct Option: D
Explanation:

BOD-Biological oxygen demand is the measure of organic matter in water

KVIC-Khadi and Village Industries Commission helps in production of biogas
LAB-Lactic acid bacteria in milk help in increasing vit B12 .
STPS-Sewagw treatment plants are used for treatment of sewage.
Correct answer-D

Limit of BOD 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. < 3.0 ppm

  2. <10 ppm

  3. < 100 ppm

  4. < 30 ppm

Show answer
Correct Option: B
Explanation:

BOD is Biological oxygen demand. It is the total amount of oxygen required by the microorganisms present in a water body to break down the organic matter. If BOD is more, it means that there is abundance of microorganisms in that water body and hence it is polluted with organic matter.

Water with BOD level 1 - 2 ppm is considered to be good water, if the BOD is 3 - 9, then the water is considered to be slightly polluted, and if the water has BOD more than 100 ppm, then the water is greatly polluted.
The Central Pollution Control Board has prescribed the limit of BOD for the discharge of industrial and municipal waste in order to regulate the water pollution and for efficient water treatment, and it is <10 ppm.

Drained sewage has B.O.D.

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

  1. More than that of water

  2. Less than that of water

  3. Equal to that of water

  4. None of the above

Show answer
Correct Option: A
Explanation:

BOD refers to the biological oxygen demand by the microbes to decompose the organic matter present in the water body. The drained sewage is rich in organic waste that will be decomposed by the bacteria. So, the drained sewage will be deficient in oxygen than the normal water. The oxygen demanded by the microbes will be higher in sewage water.

Hence, the correct answer is 'More than that of water'.

BOD is

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

  1. Biological oxygen deficit

  2. Biosphere oxygen demand

  3. Biological oxygen demand

  4. None of the above

Show answer
Correct Option: C
Explanation:

BOD refers to the Biological Oxygen Demand. It refers to the amount of the oxygen required by the aerobic bacteria to decompose the organic compounds present in the water body. If the BOD of a water body is low, it is considered to be less polluted. The high BOD shows a large level of pollution because more organic pollutants are present now and the bacteria will need more oxygen to decompose them.

Hence, the correct answer is 'Biological Oxygen Demand'.

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 $CO _2$ 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:

Biological oxygen demand refers to the amount of oxygen required for the complete decomposition of the organic mass present in the water body by the decomposing bacteria. More the amount of the organic mass, higher will be the BOD and more will be the level of pollution in the water body. As more and more oxygen will be consumed, the aquatic animals, especially fishes will die due to hypoxia. Their dead bodies will further enhance the organic mass.  

Hence, the correct answer is 'Amount of oxygen consumed by microorganisms for decaying organic matter per unit volume of water'

Limit of BOD prescribed by Central Pollution Control Board for 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. $< 3.0$ ppm

  2. $< 10$ ppm

  3. $< 30$ ppm

  4. $< 100$ ppm

Show answer
Correct Option: B
Explanation:
BOD or Biochemical oxygen demand is the amount of oxygen required to decompose the organic matter in one litre of polluted water. More BOD means more organic matter is present in the water. Hence, a high BOD value means that the water is heavily polluted. 
According to Central Pollution Control Board, limit of BOD for discharge of industrial and municipal waste waters into natural surface waters is less than 10 ppm i.e. < 10 ppm.
So, the correct answer is '< 10 ppm'

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 water

  2. Less pollution in water

  3. Less sewage

  4. Less microorganisms

Show answer
Correct Option: A
Explanation:

BOD or the Biological Oxygen Demand that is created when there is a large concentration of the organic matter in the water. To decompose this organic mass, the decomposing bacteria will be activated and there would be consumption of the dissolved oxygen in this process. So, more the organic matter, higher will be the BOD and as a result more will be the pollution in the water body. This causes severe decrease in the dissolved oxygen and kills the aquatic animals.

Hence, the correct answer is 'Highly polluted water'.

Biochemical oxygen demand in a river water 

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

  1. Remains unchanged when algal bloom occurs

  2. Increases when sewage gets mixed up with river water

  3. Has no relationship with concentration of oxygen in water

  4. Gives a measure of Salmonella in water

Show answer
Correct Option: B
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.
Hence, BOD in a river water will increase if sewage gets mixed up with the river water because more organic matter will be added in the river.
So, the correct answer is 'Increases when sewage gets mixed up with river water'.

BOD of eutrophied lake will be

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

  1. Lower

  2. Moderate

  3. Higher

  4. Same as any other lake

Show answer
Correct Option: C
Explanation:
Eutrophication is the phenomenon of nutrient enrichment of nitrogen and phosphorus in a water body that supports a dense growth of plants and animal life. Due to nutrient enrichment, excess growth of algae occurs which is called algal bloom. When these algae die, their organic matter gets decomposed and this results in the depletion of oxygen leading to death of aquatic animals. This process is called eutrophication. 
Biochemical oxygen demand or BOD is the amount of oxygen required to decompose organic matter in one litre of polluted water.
Hence, BOD of a eutrophied lake will be higher as it will have more organic matter and more oxygen will be needed to decompose it.
So, the correct answer is 'Higher'.