Tag: biology

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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

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

  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
Reveal answer Fill a bubble to check yourself
D Correct answer
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'.

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

BOD of lake becomes high by :-

  1. Vehicles

  2. Wind mill

  3. Smoke and ammonia

  4. Detergents
Reveal answer Fill a bubble to check yourself
D Correct answer
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'.
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.