Tag: effect of water pollution

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

Primary treatment reduces BOD, ranges from;

  1. 30-60%

  2. 0-70%

  3. 30-35%

  4. 20-80%
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Primary treatment in wastewater treatment typically reduces BOD by about 30-35% through physical processes like screening and sedimentation. This level of reduction is consistent with standard wastewater treatment engineering data. Higher reductions (like 30-60% or more) usually require secondary treatment with biological processes.

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

If the river water is polluted with domestic sewage and garbage, it leads to the depletion of 

  1. CO$ _2$

  2. CO
  3. O$ _2$

  4. All of the above
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A lake rich in domestic sewage and garbage nutrients will leads to eutrophication. Eutrophication is when the environment becomes enriched with nutrients. This can be a problem in aquatic habitats such as lakes as it can cause algal blooms and other aquatic plants. Following this, overcrowding occurs and plants compete for sunlight, space and oxygen. It deoxygenate the water enough to kill the fish and other animals. Thus, the correct answer is option C.

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

If BOD of river is high, it means that the river 

  1. Is not polluted

  2. Is very polluted

  3. Does not have green plants

  4. Get least amount of light
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Biochemical oxygen demand is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high demand, therefore, can indicate that levels of dissolved oxygen are falling, with potentially dangerous implications for the river's biodiversity. High biochemical oxygen demand can be caused by: high levels of organic pollution, caused usually by poorly treated waste water; high nitrate levels, which trigger high plant growth. Both result in higher amounts of organic matter in the river. When this matter decays, the microbiological activity uses up the oxygen.

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

'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
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Biochemical oxygen demand is a measure of how much dissolved oxygen is being consumed as microbes break down organic matter. A high demand, therefore, can indicate that levels of dissolved oxygen are falling, with potentially dangerous implications for the river's biodiversity. High biochemical oxygen demand can be caused by high levels of organic pollution, caused usually by poorly treated wastewater; high nitrate levels, which trigger high plant growth. 

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

Measuring 'Biochemical Oxygen Demand' (BOD) is a method used for  

  1. Estimating the amount of organic matter in sewage water.

  2. Measuring the activity of Saccharomyces cervisae in producing curd on a commercial scale.

  3. Working out the efficiency of RBCs, about their capacity to carry oxygen.

  4. Working out the efficiency of oil driven automobile engines.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Biochemical oxygen demand (BOD) is the amount of oxygen, expressed in mg/L or parts per million (ppm), that bacteria take from water, when they oxidize organic matter. 

Bacteria in water live and multiply when organic matter is available for food and oxygen is available for oxidation. About one-third of the food bacteria consumed becomes the solid organic cell material of the organisms. The other two-thirds is oxidized to carbon dioxide and water by the biochemical action of the bacteria on the oxygen dissolved in the water. 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. 

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

BOD is

  1. The-amount of $O _2$ utilised by organisms in water
  2. The amount of $O _2 $ utilised by micro organisms for decomposition
  3. The total amount of $O _2 $ present in water

  4. All of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
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. 

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. 

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

The major source of BOD in the river Ganga is 

  1. Leaf litter

  2. Fishes

  3. Human waste

  4. Aquatic plants
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Ganges river basin is one of the most fertile and densely populated regions in the world that covers an area of 1,80,000 $km^2$. The river flows through 29 cities with population over 100,000; 23 cities with population between 50,000 and 100,000, and about 48 towns. 

A large proportion of the waste in the Ganges is from this population through domestic usage like bathing, laundry and public defecation. An analysis of the Ganges water in 2006 showed significant associations between waterborne or enteric disease due to the use of the river for bathing, laundry, washing, eating, cleaning utensils, and brushing teeth.

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

'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 monooxide inseparably combined with haemoglobin.

  4. Amount of oxygen needed by green plants during night.
Reveal answer Fill a bubble to check yourself
B Correct answer
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. The BOD measures the amount of oxygen consumed by biochemical oxidation of waste contaminants. The total amount of oxygen consumed when the biochemical reaction is allowed to proceed to completion is called as the ultimate BOD. The BOD is universally adopted as a measure of relative pollution effect.