Environmental Issues Test

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Environmental Issues Test - 59

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Weekly Quiz Competition

Question 1
1 / -0

Freon gas causing stratosphere $$O_3$$ depletion is mainly released from

A
Refrigerators

B
Automobiles

C
Thermal power plants

D
Steel industry

Solution

Freon gas is a type of chlorofluorocarbon (CFC) i.e., it contains carbon and hydrogen along with fluorine and chlorine. It is used as a refrigerant. CFCs release chlorine atoms in the atmosphere that react with ozone and cause its depletion. Hence, Freon causes ozone depletion and it is released from refrigerators.
So, the correct answer is 'Refrigerators'.
Question 2
1 / -0

BOD level in fresh water should not exceed beyond

A
$$5$$ ppm

B
$$10$$ ppm

C
$$25$$ ppm

D
$$50$$ ppm

Solution

BOD or Biochemical Oxygen Demand is the amount of oxygen required to decompose organic matter present in one litre of polluted water.
More the value of BOD,more will be the amount of organic matter in the water. Hence, a high BOD value means heavily polluted water.
Water with BOD value of 1-2 ppm is considered clean.
In freshwater, BOD value should not exceed 5 ppm as the dissolved oxygen will be used up in the decomposition of organic matter and will not be available for the survival of aquatic organisms which will lead to their death.
So, the correct answer is '5 ppm'.
Question 3
1 / -0

Which is not correct approach to reduce global warming?

A
Cutting down use of fossil fuel

B
Reducing deforestation

C
Improving efficiency of energy use

D
Cutting trees and increasing growth of human population

E
Reducing emission of greenhouse gases into atmosphere

Solution

To avoid Global Warming:
1) By utilizing eco-friendly vehicles.
2) Replace normal glowing light with conservative bright light (CFL) knobs.
3)Plant more trees. By planting more trees helps in decreasing a dangerous atmospheric deviation as plants use carbon dioxide amid the procedure of photosynthesis, which is the primary driver of Global warming.
So, the correct option is 'Cutting trees and increasing the growth of the human population'.
Question 4
1 / -0

Cattle ranches cause acute green house effect because of

A
Methanogenic bacteria in rumen

B
Mechanised milking practices

C
Decomposition of organic remains in faeces

D
Decomposition of left over fodder

Solution

Cattle ranches are the grazing animals that are raised on a large land area. Cattles are responsible for green house effect because their rumen (stomach) contains methanogenic bacteria that produce methane gas which is a green house gas. Methane gas is released by the cattle in the atmosphere which then causes green house gas by trapping the radiations and this results in warming of earth's surface.
So, the correct answer is 'Methanogenic bacteria in rumen'.
Question 5
1 / -0

If there was no $$CO_2$$ in the earth's atmosphere, the temperature of the earth's surface would be _________

A
Same as the present level

B
More than the present level

C
Less than the present level

D
Dependent on $$O_2$$ content of atmosphere

Solution

Carbon dioxide atmosphere absorbs and stores the energy near the earth's surface when incoming solar radiation is reflected back to the space. If there was no carbon dioxide then there would no absorption of solar energy and hence the temperature of earth's surface would be less than the present level. So, the correct answer is 'Less than the present level'.
Question 6
1 / -0

UV radiations cause

A
Formation of thymine dimers

B
Addition of base pairs

C
Deletion of base pairs

D
Methylation of bases

Solution

UV radiation causes formation of pyrimidine dimers in DNA due to which two bases (thymine) get joined by covalent linkage to form a dimer. These dimers can lead to mutations as during replication, these dimers are skipped. However, certain enzymes are there which repair the damaged DNA.
So, the correct answer is 'Formation of thymine dimers'.
Question 7
1 / -0

$$O_3$$ in ozone layer is formed by action of

A
IR radiation

B
Blue radiation

C
UV radiation

D
Other radiations

Solution

Ozone molecule (O₃) is formed in the stratosphere in presence of UV radiations.
The first step is the breaking of an oxygen molecule into two oxygen atoms by UV radiation:
UV
$$O_2$$ ---------------> $$O$$ + $$O$$
The Oxygen atoms then combine with oxygen molecule to form a molecule of ozone:
$$O_2$$ + $$O$$ -----------------> $$O_3$$
So, the correct answer is 'UV radiation'.
Question 8
1 / -0

When domestic sewage mixes with river water, __________

A
Small animals like rats will die after drinking river water

B
The increased microbial activity released micronutrients such as iron

C
The increased microbial activity uses up dissolved oxygen

D
The river water is still suitable for drinking as impurities are only about $$0.1\%$$

Solution

Domestic sewage contains large amounts of organic matter. When domestic sewage mixes with river water, organic matter will content will increase in the river. This will lead to increase in BOD or Biochemical Oxygen Demand.
BOD is the amount of oxygen required by bacteria 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, the dissolved oxygen will be used up by the bacteria to decompose the organic matter.
So, the correct answer is 'The increased microbial activity uses up dissolved oxygen'.
Question 9
1 / -0

Polluting strength of sewage is characterised by its

A
BOD

B
Ozone content

C
Nitrogen content

D
Eutrophication

Solution

The BOD test measures the amount of dissolved oxygen in the water that is used up due to the breakdown of organic pollutants, such as sewage, in a certain number of days. Raw sewage has a BOD of forty to 150 milligrams per litre, whereas drinking water has a BOD of less than 0.5 milligrams per litre. The BOD indicates the content of oxygen needed to decompose organic compounds in wastewater by bacteria.
So the correct answer is 'BOD'.
Question 10
1 / -0

Maximum damage to forest cover is caused by

A
Edaphic factors

B
Climatic factors

C
Biotic factors

D
Physiographic factors

Solution

A. Edaphic factors are the abiotic factors that relate to structure and composition of soil.
B. Climatic factors include rain, wind, earthquake etc. which are related to climate.
C. Biotic factors are the living components of an ecosystem which include producers and consumers.
D. Physiographic factors are the factors associated with physical nature and topography of an area.
Maximum damage to forest is caused by biotic factors as overgrazing destroy vegetation and also due to human activities.
So, the correct answer is 'Biotic factors'.

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Re-Attempt Weekly Quiz Competition

Environmental Issues Test - 59

Result

Environmental Issues Test - 59

Score

-

Rank

-

SHARING IS CARING

Question 1

Refrigerators

Automobiles

Thermal power plants

Steel industry

Solution

Question 2

$$5$$ ppm

$$10$$ ppm

$$25$$ ppm

$$50$$ ppm

Solution

Question 3

Cutting down use of fossil fuel

Reducing deforestation

Improving efficiency of energy use

Cutting trees and increasing growth of human population

Reducing emission of greenhouse gases into atmosphere

Solution

Question 4

Methanogenic bacteria in rumen

Mechanised milking practices

Decomposition of organic remains in faeces

Decomposition of left over fodder

Solution

Question 5

Same as the present level

More than the present level

Less than the present level

Dependent on $$O_2$$ content of atmosphere

Solution

Question 6

Formation of thymine dimers

Addition of base pairs

Deletion of base pairs

Methylation of bases

Solution

Question 7

IR radiation

Blue radiation

UV radiation

Other radiations

Solution

Question 8

Small animals like rats will die after drinking river water

The increased microbial activity released micronutrients such as iron

The increased microbial activity uses up dissolved oxygen

The river water is still suitable for drinking as impurities are only about $$0.1\%$$

Solution

Question 9

BOD

Ozone content

Nitrogen content

Eutrophication

Solution

Question 10

Edaphic factors

Climatic factors

Biotic factors

Physiographic factors

Solution

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