Tag: our environment - our concern

Questions Related to our environment - our concern

The range of biomagnification of DDT in an aquatic food chain, if starting from 0.003 ppb level in water may go at fish-eating bird level upto:

  1. 0.3 ppm

  2. 3.0 ppm

  3. 30.0 ppm

  4. 0.003 ppm


Correct Option: B
Explanation:

The pesticides and nondegradable. They have much affinity for fats. Hence, they tend to move into living organisms. They get concentrated as they move up the food chains. For example at each trophic level, the accumulation of insecticide is increased by 10 times. For example, if the goat gets one part per million of DDT from the grass is it will have 10 parts per million in its tissues. The man eating the good will have 100 PPM. The man-eating tiger will have thousand PPM. If the food chain is still greater the accumulation will still be higher. Is increasing accumulation of insecticide and the higher organism is called biomagnification which is biological amplification.

So, the correct option is '3ppm'

Which among the following is likely to have the highest levels of DDT deposition in its body?

  1. Sea gull

  2. Phytoplankton

  3. Eel

  4. Crab


Correct Option: A
Explanation:

Chlorinated hydrocarbons like DDT pass into the food chain and increase in amount per unit weight of organisms with the rise in trophic level due to their accumulation in fat. Among the given animals, seagull which is a fish-eating bird and is present at a higher trophic level will have high levels of DDT deposition in its body.

DDT residues are rapidly passed through food chain causing biomagnification because DDT is

  1. Water soluble

  2. Lipid soluble

  3. Moderately toxic

  4. Non-toxic to aquatic animals


Correct Option: B
Explanation:
DDT is a chlorine containing pesticide used in agriculture. DDT is rapidly passed through food chain causing biomagnification because it is stable, accumulates in the soil and concentrates in the fatty tissue or internal organs of body (as DDT is fat soluble substance). So, DDT takes may years to break down and it enters into body of other organisms with predation. So the amount of DDT biomagnifies.
So, the correct answer is 'Lipid soluble'.

Which of the following causes bio-magnification?

  1. $ { SO } _{ 2 } $

  2. Mercury

  3. DDT

  4. Both (b) and (c)


Correct Option: D
Explanation:

Biomagnification refers to increase in concentration of toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted, and is thus passed on to the next higher trophic level. This phenomenon is well-known for mercury and DDT.

Which of the following statements is not correct regarding biomagnification?


(i) Mercury accumulated by an organism cannot be metabolised.
(ii) In the process of biomagnification, concentration of DDT is increased at successive trophic levels.
(iii) Accumulation of cadmium can cause thinning of eggshells in birds.
(iv) DDT accumulation is a major cause of a reduced population of fish-eating birds.
(v) Biomagnification occurs only in the aquatic food chain

  1. (i), (iii) and (v)

  2. (iii) and (iv)

  3. (iii) and (v)

  4. (i), (ii) and (iv)


Correct Option: C
Explanation:

The higher amounts of pesticide like DDT, disturb calcium metabolism of birds resulting in thinning of egg shells and their premature breaking. This is a major cause of reduction of population of fish eating birds. Biomagnification is found in all types of food chains.

The biological amplification of DDT in the various trophic levels is known as.

  1. Green house effect

  2. Biomagnification

  3. Eutrophication

  4. Pollution


Correct Option: B
Explanation:

The amplification of a toxic compound which is resistant to elimination from the body and accumulates with each trophic level is known as Bioaccumulation/Biomagnification.

So, the correct option is 'Biomagnification'.

Increase in concentration of a toxicant at successive trophic levels is called _________.

  1. Algal bloom

  2. Biomagnification

  3. Eutrophication

  4. Accelerated eutrophication

  5. Decelerated eutrophication


Correct Option: B
Explanation:

  • Algal bloom: It is the rapid growth of algae in water due to which coloured scums are formed on the surface.
  • Biomagnification: When a toxic substance gets incorporated in the food chain, its concentration gets increased at each successive trophic level. This is called biomagnification.
  • Eutrophication: It is the phenomenon of nutrient enrichment of nitrogen and phosphorus in a water body that supports a dense growth of plants and animal life. Due to nutrient enrichment, excess growth of algae occurs which is called algal bloom. When these algae die, their organic matter gets decomposed and this results in the depletion of oxygen leading to death of aquatic animals. This process is called eutrophication. 
So, the correct answer is 'Biomagnification'.

Which one of the following organism is likely to show the highest concentration of DDT once it has been introduced into the ecosystem?

  1. Snake

  2. Toad

  3. Grasshopper

  4. Cattle


Correct Option: A
Explanation:

Snake is likely to show highest concentration of DDT once it has been introduced into the ecosystem.

So, the correct option is 'Snake'.

In a lake polluted with pesticides, which one of the following will contain the maximum amount of pesticide.

  1. Small fish

  2. Microscopic animals

  3. Big fish

  4. Birds feeding on water organisms


Correct Option: C
Explanation:

If a lake is polluted with pesticides, large fish will contain the maximum amount of pesticide. The process due to which large fish will contain the maximum amount of pesticide is called biological magnification. It is also called as biomagnification. Phytoplanktons and zooplanktons absorb pesticide from the polluted water. Small fishes eats phytoplankton and zooplanktons. There will be increased accumulation of pesticide in their bodies. These small fishes are eaten by big fish. Hence, the big fish will have the maximum amount of pesticide.

Thus, the correct answer is 'Big fish.'

When the rate of the consumption of organic matter of the effluent by floes increases, then the BOD of the effluent.

  1. Significantly increases

  2. Significantly reduces

  3. No change in BOD

  4. Oxygen is not required for this process


Correct Option: A
Explanation:

  • Biochemical oxygen demand (BOD) is a measure of how much organic pollution is in water. The BOD test measures the amount of dissolved oxygen in water that is used up due to the breakdown of organic pollutants, such as sewage, in a certain number of days. 
  • Increased BOD means that a lot of oxygen is being used up, typically by bacteria breaking down organic material. 
So, the correct option is 'Significantly increases'.