Environmental Issues - Online Test

Q1. The neurotoxic form of Mercury which can be directly absorbed by fishes :
Answer : Option A
Explaination / Solution:

Mercury discharged into rivers and lakes is changed by bacteria to the neurotoxic form called methyl mercury. The latter is highly poisonous and may be directly absorbed by fish. From fishes they enter into food chain and to human by bio-magnification.

Q2. Oil spills prevent oxygenation of water so they are :
Answer : Option C
Explaination / Solution:

Physical pollution is the introduction of discarded materials into the environment. Physical pollution is what you might refer to as trash and is the direct result of human actions. In other words, nature does not produce physical pollution because in natural systems, all byproducts or wastes are eventually recycled back into the environment. For example, in nature, a fallen tree will degrade and eventually return nutrients to the soil.. Oil splits over the water bodies is the result of human activities. It prevents the oxygenation of water. It is physical pollutants.

Q3. That species which is found in highest concentration within a polluted water reservoir is called :
Answer : Option A
Explaination / Solution:

A number of organisms grow in polluted water. The species whose concentration is highest in polluted water is celled as index species as this species indicate the presence of particular kinds of pollutant in water.

Q4. Which of the following is a wrong matched pair
Answer : Option B
Explaination / Solution:

Dystrophic lake have too low accumulation of dissolved nutrients to support abundant plant life so, they have very low productivity.

Q5.

Read the following statements:
i. Based on emission, there are point and diffusion sources of water pollution.
ii. Fertilisers are example of point sources of water pollution.
iii. Industrial discharge pipes are examples of diffusion sources of water pollution.


Answer : Option B
Explaination / Solution:

On the basis of emission of pollutants in water bodies, there are point and diffusion sources of water pollution. Fertilizers are example of diffusion sources of water and industrial discharge pipes are example of point source of water pollution.

Q6. Low BOD will be characteristic feature of :
Answer : Option B
Explaination / Solution:

Low biological oxygen demand (BOD) will be characteristic feature of an oligotrophic lake. In oligotrophic lake concentration of nutrients are very low so a few organisms only survive and BOD is comparatively low.

Q7. Water bodies and aquatic flora will be badly affected by :
Answer : Option D
Explaination / Solution:

Acid rain is the rainwater that contain Sulphuric acid and Nitric acid. These acids make the water bodies acidic by changing pH. At higher pH aquatic organisms are badly affected.

Q8. Correct sequence for the amount of dissolved oxygen in water body is:

Answer : Option A
Explaination / Solution:

Dissolve oxygen in water bodies is utilized by aquatic organisms for respiration. Oligotrophic have least dissolved oxygen followed by mesotrophic and eutropic have highest concentration of dissolved oxygen.

Q9. If DDT content in the water of a lake is found to be 0.004 ppm then pelicans of that area will have:
Answer : Option A
Explaination / Solution:

DDT is used as pesticide in crop fields and to kill mosquito in open drains. DDT is not a biodegradable and reaches to nearby water bodies. DDT enters the food chain through aquatic organisms and get magnified at each trophic levels. Pelicans beings at higher trophic levels may contain upto 2 ppm DDT.

Q10. Effects of thermal pollution of water include :
a) increased BOD
b) increased toxicity of discharged chemicals
c) decreased microbial activity
Answer : Option D
Explaination / Solution:

An effect of thermal pollution of water includes increased Biological Oxygen Demand (BOD) and decreased microbial activity. Some organisms are able to survive only at normal temperature.