Environmental Issues Test

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Environmental Issues Test - 79

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Weekly Quiz Competition

Question 1
1 / -0

In the absence of greenhouse gases, the temperature of earth's surface will fall to

A
$$0^o$$C

B
$$-5^o$$C

C
$$-10^o$$C

D
$$-20^o$$C

Solution

Without the Greenhouse gases, the average temperature of earth would be 0$$^{o}$$ F or -20$$^{o}$$ C. The naturally present Greenhouse gases allow most of the incoming solar radiations to warm the earth surface and do not let the thermal radiations to escape into the space. However, anthropogenic contribution to the Greenhouse gases increase the level of solar radiations trapped and thus increase the overall temperature leading to global warming.
Hence, the correct answer is '-20$$^{o}$$ C'.
Question 2
1 / -0

Ultra-violet light causes

A
Formation of pyrimidines dimers

B
Sticky metaphases

C
Photodynamic action

D
Destruction of hydrogen bonds between complementary DNA strands

Solution

The Ultra-violet radiations are the potent mutagens as they are capable of distorting the structure of the DNA. The UV radiations cause the adjacent pyrimidines residues (thymine and cytosine) to form hydrogen bonds with each other rather than the corresponding purine residues. Generally, the thymine dimers are seen as immediate effects of the UV radiations. Due to this type of mutation, the errors in replication of DNA are frequent to observe. The breaking of hydrogen bonds between the two complementary DNA strands occurs due to increase in temperature. This is not considered as a mutation because when normal conditions arrive the hydrogen bonds can be formed again.
Hence, the correct answer is 'Formation of pyrimidines dimers'.
Question 3
1 / -0

Ozone hole over Antarctica appears during

A
Late August- Early October

B
March- April

C
October- November

D
January- February

Solution

Polar spring, also known as the Antarctic Spring is the period from late August to early October and the strong westerlies circulate around the Antarctic continent creating a polar vortex. The polar vortex results in the formation of the polar stratospheric clouds which trap most of the gases including the ozone-depleting factors like CFCs, methyl bromide etc.
Hence, the correct answer is 'Late August - Early October'
Question 4
1 / -0

Ozone hole is widest over

A
Equator

B
North pole

C
North temperate area

D
Antarctica

Solution

The ozone layer in the stratosphere is created by the interaction of the UV radiation from the sun and the oxygen. It is capable of absorbing the most damaging type of UV radiation called the UV-B. The ozone hole refers to the depletion of the ozone by the pollutants like CFCs, HCFCs and HFCs. The pollutants split up due to UV radiation and the nascent chlorine reacts with the ozone molecules to form the oxygen. Over Antarctica, the ozone is highly depleted and so the widest ozone hole is seen there. This is because of the presence of the stratospheric cloud in abundance.
Hence, the correct answer is 'Antarctica'
Question 5
1 / -0

CFCs split up in stratosphere to release chlorine by the action of

A
UV - A

B
UV - B

C
UV - C

D
All of the above

Solution

The UV-C radiations breakdown the bonds in the chlorofluorocarbons (CFCs) to release the chlorine monoxide and the nascent chlorine. These further react with the ozone to split it into ordinary oxygen molecules. The oxygen molecules are further broken down into nascent oxygen, which acts as the radicle.
Hence, the correct answer is 'UV-C'.
Question 6
1 / -0

Ozone depletion shall cause higher incidence of

A
Skin cancers

B
Cataract

C
Decreased immunity

D
All of the above

Solution

Ozone depletion causes the harmful UV-B radiations to strike the earth surface. These radiations are capable of causing various health issues like malignant skin cancers, cataract, decreased immunity, decreased primary productivity, chlorophyll bleaching etc.
Hence, the correct answer is 'All of the above'
Question 7
1 / -0

Ozone hole over Antarctica was first detected by

A
Molina and Rowland

B
Farman et al

C
Augus

D
Molina and Molina

Solution

The discovery of the ozone hole over Antarctica was done by British Antarctic Survey Scientist Farman, Gardiner and Shanklin and reported in the Nature journal in May 1985. The ozone hole is defined as the area in the atmosphere where the value of the ozone is less than 220 DU. Paul Crutzen, Mario Molina and Sherwood Rowland gave the observation of CFCs in degradation of the ozone.
Hence, the correct answer is 'Farman et al'.
Question 8
1 / -0

Chief air pollutant which is likely to deplete ozone layer is ________.

A
Sulphur dioxide

B
Carbon dioxide

C
Carbon monoxide

D
Nitrogen oxides and fluorocarbons

Solution

The ozone depleting substances include the chlorofluorocarbons, oxides of nitrogen, methyl bromide, carbon tetrachloride etc because these split up when exposed to UV radiations and release the reactive chlorine and bromine. These reactive species of chlorine and bromine then react with ozone to release the nascent oxygen. Sulphur dioxide and carbon dioxide are greenhouse gases. Carbon monoxide is an air pollutant.
Hence, the correct answer is 'Nitrogen oxides and fluorocarbons'.
Question 9
1 / -0

Measurement of rate of oxygen utilisation by a unit volume of water over a period of time is to measure

A
Fermentation

B
Biogas generation

C
Biosynthetic pathway

D
Biological oxygen demand

Solution

Biological Oxygen Demand (BOD) in simple terms is the amount of oxygen that would be used by the decomposing bacteria to decompose or break down the organic compounds in the water body. The increase in the BOD reflects that the concentration of the organic mass is tremendous and so a large amount of oxygen would be claimed by the bacteria. This results in the deficiency of the dissolved oxygen in the water and adversely affects the aquatic life due to hypoxia. So, the BOD can be defined as the measurement of the rate of oxygen utilization by a unit volume of water over a period of time.
Hence, the correct answer is 'Biological oxygen demand'.
Question 10
1 / -0

Increasing skin cancer and high mutation rate are due to _________.

A
Acid rain

B
Ozone depletion

C
CO pollution

D
$$CO_2$$ pollution

Solution

The ozone layer in the stratosphere is useful because it absorbs the UV radiations from the sun and prevents them from reaching the earth's surface. The depletion of the ozone by the ozone-depleting substances causes the break down of the ozone resulting in the ozone depletion. Due to this, the lives on the earth's surface are exposed to the UV rays. These UV rays induce mutations in the DNA by distorting its structure, leading to the erroneous function and replication of the DNA. The uncontrolled errors at times cause uncontrolled cell proliferation, causing skin cancer.
Hence, the correct answer is 'Ozone Depletion'.

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Re-Attempt Weekly Quiz Competition

Environmental Issues Test - 79

Result

Environmental Issues Test - 79

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SHARING IS CARING

Question 1

$$0^o$$C

$$-5^o$$C

$$-10^o$$C

$$-20^o$$C

Solution

Question 2

Formation of pyrimidines dimers

Sticky metaphases

Photodynamic action

Destruction of hydrogen bonds between complementary DNA strands

Solution

Question 3

Late August- Early October

March- April

October- November

January- February

Solution

Question 4

Equator

North pole

North temperate area

Antarctica

Solution

Question 5

UV - A

UV - B

UV - C

All of the above

Solution

Question 6

Skin cancers

Cataract

Decreased immunity

All of the above

Solution

Question 7

Molina and Rowland

Farman et al

Augus

Molina and Molina

Solution

Question 8

Sulphur dioxide

Carbon dioxide

Carbon monoxide

Nitrogen oxides and fluorocarbons

Solution

Question 9

Fermentation

Biogas generation

Biosynthetic pathway

Biological oxygen demand

Solution

Question 10

Acid rain

Ozone depletion

CO pollution

$$CO_2$$ pollution

Solution

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