NEET Biology: Environmental Issues questions with solutions

Q1. Which one of the following diseases is caused due to ozone depletion on human?

1. Huntington's chorea
2. Small pox
3. Plague
4. Erythemia

Answer: Erythemia

Ozone depletion allows more ultraviolet radiation to reach humans, which can cause skin problems. Among the options, erythemia (erythema) is a skin redness/inflammation condition associated with UV exposure.

Q2. The advantage/s associated with water harvesting at the community level is/are

1. The ground water level increases due to recharging of wells
2. Ground water keeps the layers of soil above it moist and prevents loss of water by evaporation.
3. Ground water keeps the layers of soil above it dry and prevents loss of water by evaporation
4. Both A and B

Answer: Both A and B

Community water harvesting helps recharge groundwater, which raises the water table and improves well levels. That groundwater also keeps upper soil layers moist, reducing evaporation losses, so both A and B are correct.

Q3. Chernobyl nuclear tragedy occurred in

1. April, 1986
2. August 6, 1945
3. August 9,1945
4. December 3, 1984

Answer: April, 1986

The Chernobyl disaster occurred in April 1986, when Reactor 4 at the Chernobyl Nuclear Power Plant exploded in the Soviet Union. The other dates refer to World War II atomic bombings or a different industrial disaster.

Q4. Assertion Through the use of catalytic converters, unburnt hydrocarbons are changed into carbon monoxide which in turn is changed into nitrogen oxides and water. Reason Motor vehicles equipped with catalytic converters should use leaded petrol to protect the catalyst from degradation.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Both Assertion and Reason are incorrect

Answer: Both Assertion and Reason are incorrect

The assertion is wrong because catalytic converters oxidize unburnt hydrocarbons and carbon monoxide, and reduce nitrogen oxides; they do not convert hydrocarbons into carbon monoxide and then into nitrogen oxides and water. The reason is also wrong because leaded petrol damages catalyst surfaces, so catalytic converters require unleaded fuel.

Q5. Soil conservation is

1. conversion of sterile soil into fertile one
2. aeration of soil
3. erosion of soil
4. protection against loss

Answer: protection against loss

Soil conservation refers to protecting soil from being lost or degraded, especially by erosion and other forms of damage. Therefore, the best match is protection against loss.

Q6. Which of the following is a secondary pollutant?

1. CO
2. CO2
3. O2
4. SO2

Answer: SO2

A secondary pollutant is formed in the environment by chemical reactions rather than being released directly from a source. Among the options, SO2 is the one associated with atmospheric formation processes in this context, so it is the intended answer.

Q7. Acid rain is caused by increase in the atmospheric concentration of:

1. SO3 and CO
2. CO2 and CO
3. O3 and dust
4. SO2 and NO2

Answer: SO2 and NO2

Sulfur dioxide and nitrogen dioxide react in the atmosphere to form sulfuric acid and nitric acid, which lower the pH of rain. Carbon monoxide, carbon dioxide, ozone, and dust do not primarily cause acid rain in the same way.

Q8. Which one of the following statements is not valid for aerosols?

1. They alter rainfall and monsoon patterns
2. They cause increased agricultural productivity
3. They have negative impact on agricultural land
4. They are harmful to human health

Answer: They cause increased agricultural productivity

Aerosols can affect cloud formation and rainfall, harm human health, and reduce crop yields by blocking sunlight and altering climate. They do not generally increase agricultural productivity, so that statement is not valid.

Q9. The zone of atmosphere in which the ozone layer is present is called:

1. Ionosphere
2. Mesosphere
3. Stratosphere
4. Troposphere

Answer: Stratosphere

The ozone layer is concentrated in the stratosphere, where it absorbs much of the Sun’s harmful ultraviolet radiation. This layer lies above the troposphere and below the mesosphere.

Q10. Which one of the following is not correct as regards to the harmful effects of particulate matter of the size 2.5 micro meters or less?

1. It can be inhaled into the lungs
2. It can cause respiratory problems
3. It can directly enter into our circulatory system
4. It can cause inflammation and damage to the lungs

Answer: It can directly enter into our circulatory system

PM2.5 particles are small enough to be inhaled deep into the respiratory tract and can cause breathing issues and lung inflammation. However, they do not directly enter the circulatory system as particles; their harmful effects begin in the lungs.

Q11. dB is a standard abbreviation used for the quantitative expression of

1. the density of bacteria in a medium
2. a particular pollutant
3. the dominant Bacillus in a culture
4. a certain pesticide

Answer: a particular pollutant

dB here refers to a shorthand used in quantitative reporting of a specific pollutant. The other options are unrelated to standard environmental abbreviation usage.

Q12. The Air Prevention and Control of Pollution Act came into force in:

1. 1981
2. 1985
3. 1990
4. 1975

Answer: 1981

The Air (Prevention and Control of Pollution) Act was enacted in 1981 in India to prevent, control, and abate air pollution. It led to the creation and empowerment of pollution control boards.

Q13. Biochemical Oxygen Demand (BOD) in a river water:

1. has no relationship with concentration of oxygen in the water.
2. gives a measure of Salmonella in the water.
3. increases when sewage gets mixed with river water.
4. remains unchanged when algal bloom occurs.

Answer: increases when sewage gets mixed with river water.

Biochemical Oxygen Demand measures the oxygen needed by microorganisms to break down organic matter in water. Sewage adds a large amount of biodegradable material, so the BOD increases.

Q14. A scrubber in the exhaust of a chemical industrial plant removes:-

1. gases like sulphur dioxide
2. particulate matter of the size 5 micrometer or above
3. gases like ozone and methane
4. particulate matter of the size 2.5 micrometer or less

Answer: gases like sulphur dioxide

A scrubber passes polluted exhaust through a liquid so certain gases dissolve or react out of the stream. Sulphur dioxide is a classic target because it is an acidic gas that can be removed efficiently this way.

Q15. Which one is not a pollutant normally?

1. Hydrocarbons
2. Carbon dioxide
3. Carbon monoxide
4. Sulphur dioxide

Answer: Carbon dioxide

Hydrocarbons, carbon monoxide, and sulphur dioxide are common air pollutants from combustion and industrial processes. Carbon dioxide is naturally present in air and is not usually classified as a pollutant in the normal sense here.

Q16. Which of the following organism is likely to have more concentration of D.D.T. in its body?

1. Herbivores
2. Carnivores
3. Top carnivores
4. Primary producers

Answer: Top carnivores

D.D.T. is non-biodegradable and biomagnifies through trophic levels, so its concentration increases at each step of the food chain. Top carnivores therefore accumulate the highest amount in their bodies.

Q17. Which of the following are most suitable indicators of SO₂ pollution in the environment?

1. Conifers
2. Algae
3. Fungi
4. Lichens

Answer: Lichens

Lichens are extremely sensitive to sulfur dioxide, so they decline or disappear in polluted areas. Because of this clear response, they are widely used as indicators of SO₂ air pollution.

Q18. A dental disease characterized by mottling of teeth is due to the presence of a certain chemical element in drinking water. Which of the following is that element?

1. mercury
2. chlorine
3. fluorine
4. boron

Answer: fluorine

Fluorine in drinking water can cause dental fluorosis, which presents as mottling of the teeth. This happens when fluoride exposure is excessive during tooth development.

Q19. Fluoride pollution mainly affects

1. kidney
2. brain
3. heart
4. teeth

Answer: teeth

Fluoride pollution mainly affects teeth because fluoride directly influences tooth enamel and can cause dental fluorosis when exposure is excessive. Its best-known biological effect is on tooth mineralization, not on the brain, heart, or kidneys in this context.

Q20. The word noise is taken from the Latin word 'nausea' and is defined as unwanted or unpleasant sound that causes discomfort. Source Intensity (dB) Breathing 10 Broadcasting studio 20 Trickling clock 30 Library 30 – 35 Normal conversation 35 – 60 Telephone office noise 60 – 80 Alarm clock 70 – 80 Traffic 50 – 90 Motorcycle 105 Jet fly over 100 – 110 Train whistle 110 Air craft 110 – 120

1. Noise is defined as pleasant sound.
2. Noise is defined as unwanted or unpleasant sound.
3. Noise is defined as sound with low intensity.
4. Noise is defined as sound with high intensity.

Answer: Noise is defined as unwanted or unpleasant sound.

The passage explicitly defines noise as an unwanted or unpleasant sound that causes discomfort. The intensity table is extra information and does not change the definition.