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The effects of human activities on ecosystems - class-IX

Description: the effects of human activities on ecosystems
Number of Questions: 59
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Tags: our environment - our concern ecology and environment our environment option c: ecology and conservation environmental issues zoology conservation of plants and animals biology soil pollution
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The largest freshwater lake in India is

  1. Chilka lake

  2. Kolleru lake

  3. Wular lake

  4. None of the above


Correct Option: B
Explanation:
Kolleru lake is the largest freshwater lake in India and is located in Andhra Pradesh. Kolleru is located between the Krishna and Godavari delta. Thus the correct answer is option B.

Kolleru lake hosts

  1. Shovellers

  2. Pintails

  3. Teals

  4. All of the above


Correct Option: D
Explanation:
Kolleru lake is the largest freshwater lake in India and is located in Andhra Pradesh. Kolleru is located between the Krishna and Godavari delta. The Kolleru Bird Sanctuary is situated adjoining the lake and covers about 673 square kilometers of marshland. This sanctuary is a home to migratory birds like teals, pintails, and shovellers. Thus, the correct answer is option D.

The water holding capacity of Kolleru lake has been reduced due to

  1. Urbanization

  2. Eutrophication

  3. Dam construction

  4. Both A and B


Correct Option: D
Explanation:


Kolleru lake is the largest freshwater lake in India and is located in Andhra Pradesh. Kolleru is located between the Krishna and Godavari delta. The lake is drying up due to indiscriminate exploitation and urbanization. Kolleru Lake receives a lot of nutrients, leading to eutrophication. The lake’s eutrophication and deterioration in ecological health have occurred steadily and consistently and has thus decreased its water holding capacity. Thus the correct answer is option D.

Which is the correct pair of biological magnification?

  1. Water - $0.0003$ ppm

  2. Small fishes - $0.2$ ppm

  3. Big fishes - $2$ ppm

  4. Zoo plaktery - $0.4$ ppm


Correct Option: C
Explanation:

Biological magnification is also called as biomagnification and bioamplification. It occurs due to the increasing concentration of a toxic substance in the tissues of tolerant organisms that successively move up to higher levels in a food chain. The order of food chain for the given example is water followed by zoo plaktery followed by small fishes and lastly big fishes. It usually increase 2 to 10 folds in a food chain. Hence, the biomagnification of water, that is 0.0003 ppm is too less. Also, biomagnification of small fishes (0.2 ppm) should be ideally more than zoo plaktery (0.4 ppm). Hence, options A, B and D are incorrect. Big fishes having hightest biomagnification, that is 2 ppm.

Thus, the correct answer is 'Big fishes - 2 ppm.'

Which of the following is the correct order of biomagnification of DDT in an aquatic food chain?

  1. Water- $0.003$ ppm, zooplankton- $0.5$ppm, small fish- $0.04$ppm, large fish -$2$ppm, fish eating birds-$25$ppm

  2. Water-$0.003$ppm, zooplankton-$0.04$ppm, small fish-$0.5$ppm, large fish-$2$ppm, fish eating birds-$25$ppm

  3. Water-$0.003$ppm, small fish-$0.04$ppm. zooplankton-$0.5$ppm, large fish-$2$ppm, fish eating birds-$25$ppm

  4. Water-$0.003$ ppm, fish eating birds-$25$ppm, zooplankton-$0.5$ppm, small fish-$0.04$ppm, large fish-$2.5$ppm

  5. Water-$0.003$ppm, large fish-$0.04$ppm, small fish-$0.5$ppm, zooplankton-$2$ppm, fish eating birds-$25$ ppm


Correct Option: B
Explanation:
DDT is not soluble in water, so it will be least in water (0.003 ppm). It is seen that the level of DDT increases as the food chain progresses. It means, the primary consumers (zooplankton) will have more DDT concentration than the producers, the secondary consumers (small fish) will have more than primary consumers and so on. The highest concentrations will be seen in the top carnivore (fish eating bird). This is because the consumers at the successive trophic level consume more than the previous level to fulfil the energy requirements. Due to this, DDT keeps on accumulating in the successive trophic levels in higher concentrations. This process is called the biomagnification. 
Hence, the correct answer is 'Water-0.003ppm, zooplankton- 0.04ppm, small fish-0.5ppm, large fish-2ppm, fish eating birds-25ppm'

Biological magnification occurs in case of

  1. Organochlorine insecticides

  2. Organophosphate pesticides

  3. Plants and animals in ecosystem with abundant resources

  4. Photography


Correct Option: A
Explanation:

DDT (Dichlorodiphenyltrichloroethane) is basically an organochlorine pesticide/insecticide. It was originally used for insecticides to prevent the crop from being damaged by insects, rodent, weeds etc. but due to its harmful effect it has been globally banned by "Stockholm convention on Persistent organic pollutant, 2001". By its nature, it is insoluble in water and shows high solubility in the fat of animals. They do not degrade easily and accumulate within the body of the organism in fat deposited portion. Due to their ability to show the biomagnification.

Hence, the correct answer is 'Organochlorine insecticides'.

A hyper metal accumulator is

  1. Daucos carota

  2. Nicotiana tabacum

  3. Arabidopsis

  4. Thlaspi goesingensis


Correct Option: C
Explanation:

Plants are categorised into three groups based on their uptake of heavy metals - indicator, excluder and hyperaccumulator. Hyperaccumulator is a plant capable of growing in soils with high concentration of metals. They absorb through their roots and concentrate them in their tissues. The concentration is toxic to other species not adapted to grow on such soil. Arabidopsis belonging to the family Brassicaceae is a hyperaccumulator. Hence, the correct answer is 'Arabidopsis'.

As it passes into food chain, the concentration of DDT

  1. Remains same

  2. Decreases

  3. Increases

  4. Unpredictable


Correct Option: C
Explanation:

DDT (Dichlorodiphenyltrichloroethane) is an organochlorinated compound that is stable in nature. It is highly soluble in the fats of the living organism and so, it shows persistence in the food chain. It is seen that the level of DDT increases as the food chain progresses. It means, the primary consumers will have more DDT concentration than the producers, the secondary consumers will have more than primary consumers and so on. The highest concentrations will be seen in the top carnivore. This is because the consumers at the successive trophic level consume more than the previous level to fulfil the energy requirements. Due to this, DDT keeps on accumulating in the successive trophic levels in higher concentrations. This process is called the biomagnification.

Hence, the correct answer is 'Increases'.

Concentration of DDT from lower to higher trophic level _________.

  1. Increases

  2. Decreases

  3. Increases or decreases

  4. Remains constant


Correct Option: A
Explanation:

DDT (Dichlorodiphenyltrichloroethane) is an organochlorinated compound that is stable in nature. It is highly soluble in the fats of the living organism and so, it shows persistence in the food chain. It is seen that the level of DDT increases as the food chain progresses. It means, the primary consumers will have more DDT concentration than the producers, the secondary consumers will have more than primary consumers and so on. The highest concentrations will be seen in the top carnivore. This is because the consumers at the successive trophic level consume more than the previous level to fulfil the energy requirements. Due to this, DDT keeps on accumulating in the successive trophic levels in higher concentrations. This process is called the biomagnification.

Hence, the correct answer is 'Increases'.

Highest DDT deposition shall occur in

  1. Phytoplankton

  2. Sea Gull/Birds

  3. Crab

  4. Eel


Correct Option: B
Explanation:

Dichlorodiphenyltrichloroethane (DDT) is chemically an organochlorine that was used an insecticide. It is a stable compound that shows high solubility in the fatty tissues. When it is released in the water via the agricultural field surface run-off, it is ingested by the aquatic organisms like phytoplankton that are main producers in an aquatic food chain. From these, DDT continues rising up the food chain. Because successive consumers at the successive trophic level consume more food, it accumulates at the higher trophic level in greater amounts. This is called biomagnification. Sea/gulls and birds are the top consumers in an aquatic food chain, they will show the highest accumulation.

Hence, the correct answer is 'Sea Gull/Birds'.

What is the consequence of the spray of pesticides in the environment which threatens the predators in the area?

  1. Global warming

  2. Eutrophication of lakes

  3. Depletion of the ozone layer

  4. Magnification in the food chain

  5. Acid rain


Correct Option: D
Explanation:
Slow metabolism and excretion of pesticides causes their accumulation in fat tissues of organisms and is referred to as biomagnifications. It particularly affects the top consumers (predators) of that food chain due to the higher concentration of toxic compounds. Thus, the correct answer is D.

Drinking aerated drink with low levels (0.02 ppm) of pesticide for long period would cause

  1. Cancer of intestine

  2. Accumulation in the body

  3. Leukaemia

  4. Immunity against mosquito


Correct Option: B
Explanation:

There are pesticides which have been detected in the aerated soft drinks by the researchers. These pesticides are known to accumulate within the tissues of the body. The permissible limit of pesticides in drinking water is 0.02 ppm. The accumulation of the pesticides may result in interference in the metabolic activities of the body. There are certain pesticides which are toxic and accumulation might degrade the tissues. 

Thus, the correct answer is option B. 

Drinking mineral water drink with low levels ($\sim$ 0.02 ppm) of pesticide for long period would

  1. Cause cancer of intestine.

  2. Lead to accumulation of pesticides in the body.

  3. Cause leukaemia in most of the people.

  4. Produce immunity against mosquito.


Correct Option: B
Explanation:

In India, prolonged use of 0.02-13 ppm of DDT (pesticide) can be detected in the body fat of the people. Most toxic pollutants such as pesticides do not degrade easily and therefore accumulate within the body of an organism specially in fat deposited portion. This process is known as biochemical concentration.

Therefore, the correct answer is option B.

Maximum DDT is present in birds feeding on 

  1. Fishes

  2. Meat

  3. Insects

  4. Seeds


Correct Option: A
Explanation:

A few toxic substances, often present in industrial wastewaters, can undergo biological magnification in the aquatic food chain. Biomagnification refers to increase in the concentration of the 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. The concentration of DDT is increased  at successive trophic levels. For example, if it starts at 0.003 ppb (ppb = parts per billion) in water, it can ultimately reach 25 ppm (ppm = parts per million) in fish-eating birds, through biomagnification. 

High concentrations of DDT disturb calcium metabolism in birds, which causes thinning of eggshell and their premature breaking, eventually causing a decline in bird populations. 

Biomagnification of DDT in an aquatic food chain starting from water having a concentration of 0.003 ppm may go, in fish eating ...... up to 

  1. 2 ppm

  2. 25 ppm

  3. 50 ppm

  4. 100 ppm


Correct Option: B
Explanation:

Biomagnification refers to increase in concentration of the 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. In this manner, the concentration of DDT is increased  at successive trophic levels; e.g., if it starts at 0.003 ppb (ppb = parts per billion) in water, it can ultimately reach 25 ppm (ppm = parts per million) in fish-eating birds, through biomagnification.

Biomagnification refers to an increase in the concentration of the toxicant at successive trophic levels. This happens because

  1. A toxic substance accumulated by an organism cannot be metabolised

  2. A toxic substance accumulated by an organism cannot be excreted

  3. A toxic substance passed on to the next highest trophic level

  4. All of the above


Correct Option: D
Explanation:

Biomagnification, also known as bioamplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain. Biomagnification process occurs when certain toxic chemicals and pollutants such as heavy metals, pesticides or polychlorinated biphenyls (PCBs) compounds go up the food chain by working their way through the environment and into the soil or the water systems after which they are eaten by aquatic animals or plants. Biomagnification occurs in the higher trophic levels of the food chain/web , where exposure to chemicals takes place mostly through food consumption rather than water uptake. Spraying a marsh to control mosquitoes will cause trace amounts of DDT to accumulate in the cells of microscopic aquatic organisms causing accumulation which cannot be metabolized.

So the correct option is 'all of the above'

Multiple Choice Questions
Biomagnification of DDT causes decline in bird population by

  1. Disturbing Ca metabolism

  2. Thinning of egg shells

  3. Premature breaking of egg shells

  4. All the above.


Correct Option: D
Explanation:
Biomagnification refers to an increase in concentration of toxic substances due to its accumulation at successive trophic levels. Biomagnification of DDT disturbs calcium metabolism in birds leading to thinning of eggshells and its premature breaking. It also leads to a significant decrease in their population.
So, the correct answer is option D, all the above.

In a highly pesticide polluted pond, which of the following aquatic organisms will have the maximum amount of pesticide per gram of body mass?

  1. Lotus

  2. Fishes

  3. Spirogyra

  4. Zooplanktons


Correct Option: B
Explanation:

Biomagnification is the process where the concentration of toxic compounds increases in the body of the organisms through the food chain. The organisms at the higher trophic level will have more concentration of the compounds. Here, fishes are at the highest trophic level, so they will accumulate maximum amount of pesticides. So, the correct answer is 'Fishes'.

Which of the following is a result of biological magnification?

  1. Top predators may be most harmed by toxic environmental chemicals

  2. DDT has spread throughout every ecosystem and is found in almost every organism

  3. Biosphere is able to regulate the environment and adjust to disruptions

  4. Many nutrients are being removed from agricultural lands and shunted into aquatic ecosystems


Correct Option: A
Explanation:

Biological magnification is the process of increasing concentration of the toxic substances in the living organism as they go up the food chain.

So, the top predators are harmed the most by toxic elements.
So, the correct option is 'Top predators may be most harmed by toxic environmental chemicals'

Which of the following statements is related to biological magnification?

  1. There is a progressive increase in biological activities through trophic levels

  2. There is a progressive increase in the level of harmful substances through trophic levels.

  3. There is a progressive increase in the body weight through trophic levels.

  4. There is a progressive increase in the number of organisms through trophic levels.


Correct Option: B
Explanation:

The toxic substances which cannot be metabolized get accumulated at a particular trophic level. This leads to increase in the concentration of the toxicant at successive trophic levels. This phenomenon is called as biological magnification and well-known for mercury and DDT. Higher the trophic level of an organism in the food chain greater will be the magnification of toxic chemicals.

So, the correct answer is option B.

If a water body is contaminated with toxicant, its biomagnification will be more marked in

  1. Plankton

  2. Small fish

  3. Birds

  4. Water


Correct Option: C
Explanation:

 It is seen that the level of toxicant increases as the food chain progresses. It means, the primary consumers will have more toxicant concentration than the producers, the secondary consumers will have more than primary consumers and so on. The highest concentrations will be seen in the top carnivore. This is because the consumers at the successive trophic level consume more than the previous level to fulfil the energy requirements. Due to this, toxicant keeps on accumulating in the successive trophic levels in higher concentrations. This process is called the biomagnification. So, planktons will have least and birds will have the most toxicant presence.

Hence, the correct answer is 'Birds'.

Match the columns and find correct option.

I(Organisms) II(DDT in ppm)
(a) Zooplankton (p) $0.003$ ppm
(b) Small fishes (q) $2.0$ ppm
(c) Water (r) $25.0$ ppm
(d) Fish eating birds (s) $0.04$ ppm
(e) Big fishes (t) $0.5$ ppm
  1. a-s, b-t, c-p, d-r, e-q

  2. a-s, b-t, c-r, d-q, e-p

  3. a-s, b-t, c-p, d-q, e-r

  4. a-q, b-p, c-s, d-t, e-r


Correct Option: A
Explanation:
  • Biomagnification refers to an increase in the concentration of the toxicant at successive trophic levels. This happens because a toxic substance accumulated by an organism cannot be metabolized or excreted, and is thus passed on to the next higher trophic level. This phenomenon is well-known for mercury and DDT. 
  • Biomagnification of DDT in an aquatic food chain as follows,
  • (a)Zooplankton - (s)0.04ppm.
  • (b)Small Fishes - (t) 0.5ppm.
  • (c)Water             -(p)0.003ppm.
  • (d)Fish-eating birds -(r)25.0ppm.
  • (e)Big Fishes - (q)2 ppm.

Increase in the concentration of the toxicant at successive trophic levels is known as

  1. Biomagnification

  2. Biodeterioration

  3. Biotransformation

  4. Biogeochemical cycling


Correct Option: A
Explanation:

Biomagnification, also known as bio-amplification or biological magnification, is the increasing concentration of a substance, such as a toxic chemical, in the tissues of tolerant organisms at successively higher levels in a food chain. The substances become increasingly concentrated in tissues or internal organs as they move up the chain. Bioaccumulants are substances that increase in concentration in living organisms as they take in contaminated air, water, or food because the substances are very slowly metabolized or excreted.

So the correct answer is 'Biomagnification'.

Calcium metabolism in birds gets disturbed due to effect of ___________

  1. Mercury

  2. Cadmium

  3. DDT

  4. Lead

  5. Copper


Correct Option: C
Explanation:
Dichlorodiphenyltrichloroethane or DDT is a crystalline, colourless and odourless compound which is used as an insecticide. DDT on runoff from the fields reach the water bodies and gets accumulated in the bodies of fishes. When fishes are eaten by birds, it gets accumulated in the body of birds and hence, in this way it gets incorporated in the food chain. With each successive trophic level, concentration of DDT increases and this is known as biomagnification. 
High concentration of DDT disturbs the calcium metabolism of birds and reptiles and causes thinning of egg shells. and premature breaking. This leads to decline in their population.
So, the correct answer is 'DDT'.

In an area where DDT has been used extensively, bird population declined because

  1. Birds stopped laying eggs

  2. Earthworms disappeared

  3. Cobras started feeding on birds

  4. Many birds eggs did not hatch


Correct Option: D
Explanation:
Dichlorodiphenyltrichloroethane or DDT is a crystalline, colourless and odourless compound which is used as an insecticide. DDT on runoff from the fields reach the water bodies and gets accumulated in the bodies of fishes. When fishes are eaten by birds, it gets accumulated in the body of birds and hence, in this way it enters the food chain. With each successive trophic level, concentration of DDT increases and this is known as biomagnification. 
High concentration of DDT disturbs the calcium metabolism of birds and reptiles and causes thinning of egg shells. and premature breaking. This leads to decline in their population. Very high concentrations of DDT can result in failure of hatching of eggs.
So, the correct answer is 'Many birds eggs did not hatch'.


Biomagnification of DDT causes decline in bird population by

  1. Brining disturbance in calcium metabolism

  2. Thinning of egg shell

  3. Premature breaking of eggs

  4. All of the above


Correct Option: D
Explanation:
Dichlorodiphenyltrichloroethane or DDT is a crystalline, colourless and odourless compound which is used as an insecticide. DDT on runoff from the fields reach the water bodies and gets accumulated in the bodies of fishes. When fishes are eaten by birds, it gets accumulated in the body of birds and hence, in this way it enters the food chain. With each successive trophic level, concentration of DDT increases and this is known as biomagnification. 
High concentration of DDT disturbs the calcium metabolism of birds and causes thinning of egg shells. and premature breaking. This leads to decline in their population.
Hence, all the options are correct.
So, the correct answer is 'All of the above'.

DDT residues are rapidly passed through food chain as DDT is

  1. Water soluble

  2. Moderately toxic

  3. Liposoluble

  4. Nontoxic to aquatic animals


Correct Option: C
Explanation:
Dichlorodiphenyltrichloroethane or DDT is a crystalline, colourless and odourless compound which is used as an insecticide. DDT on runoff from the fields reach the water bodies and gets accumulated in the bodies of fishes. When fishes are eaten by birds, it gets accumulated in the body of birds and hence, in this way it gets incorporated in the food chain. It gets deposited in the fatty tissues of animals as it is fat soluble and cause serious health hazards. 
Hence, DDT residues are rapidly passed through food chain as DDT is fat soluble i.e. liposoluble.
So, the correct answer is 'Liposoluble'.

Pollution caused by persistent pesticides is more hazardous to

  1. Herbivores

  2. Producers

  3. First level carnivores

  4. Top carnivores


Correct Option: D
Explanation:

Persistent pesticides are stable in chemical nature and tend to solubilize in the fats of the living organisms, these show persistence in the food chain. It is seen that the level of persistent pesticides increases as the food chain progresses. It means, the primary consumers will have more persistent pesticides concentration than the producers, the secondary consumers will have more than primary consumers and so on. The highest concentrations will be seen in the top carnivore. This is because the consumers at the successive trophic level consume more than the previous level to fulfil the energy requirements. Due to this, persistent pesticides keep on accumulating in the successive trophic levels in higher concentrations. This process is called the biomagnification.

Hence, the correct answer is 'Top carnivores'.

Process by which insecticides like DDT reach man is

  1. Bioaccumulation

  2. Biomagnification

  3. Bioremediation

  4. Eutrophication


Correct Option: B
Explanation:

DDT is an organochlorinated compound that was used as an insecticide. It is highly stable and is not degradable. It tends to stay in the adipose tissue of the living organisms. Due to this property, it enters the food chain and is accumulated at each trophic level. As the primary consumers eat more producers and similarly, secondary consumers eat more primary consumers, the organisms at the higher trophic levels will have an increased concentration of DDT. This process is called d the boimagnification.

Hence, the correct answer is 'Biomagnification'.

Cause of decline in population of reptiles and birds is

  1. Bioinsecticides

  2. Biofetilizers

  3. DDT

  4. Both A and B


Correct Option: C
Explanation:
A. Bioinsecticides are the biological agents or organisms that are used to control pests.
B. Biofertilizers are the microorganisms that are used to supply nutrients in the soil and increase its fertility.
C. Dichlorodiphenyltrichloroethane or DDT is a crystalline, colourless and odourless compound which is used as an insecticide. DDT on runoff from the fields reach the water bodies and gets accumulated in the bodies of fishes. When fishes are eaten by birds, it gets accumulated in the body of birds and hence, in this way it enters the food chain. With each successive trophic level, concentration of DDT increases and this is known as biomagnification. 
High concentration of DDT disturbs the calcium metabolism of birds and reptiles and causes thinning of egg shells. and premature breaking. This leads to decline in their population.
So, the correct answer is 'DDT'.

Biomagnification refers to

  1. Rapid growth due to excessive intake of nutrients

  2. Increase in population size

  3. Decrease in population size

  4. Increase in concentration of nondegradable pollutants as they pass through food chain.


Correct Option: D
Explanation:

Biomagnification is the property of a toxin to accumulate in the food chain by solubilizing with the adipose tissues of the living organisms. It is seen that the level of nondegradable pollutants increases as the food chain progresses. It means, the primary consumers will have more nondegradable pollutants concentration than the producers, the secondary consumers will have more than primary consumers and so on. The highest concentrations will be seen in the top carnivore. This is because the consumers at the successive trophic level consume more than the previous level to fulfil the energy requirements. Due to this, nondegradable pollutants keeps on accumulating in the successive trophic levels in higher concentrations. This process is called the biomagnification.

Hence, the correct answer is 'Increase in concentration of nondegradable pollutants as they pass through food chain.'

Match the following Column I with Column II.

Column I Column II
A. Zooplankton 1. 0.003 ppm
B. Small fishes 2. 2 ppm
C. Water 3. 25 ppm
D. Fish eating birds 4. 0.04 ppm
E. Big fishes 5. 0.5 ppm
  1. A - 2, B - 1, C - 4, D - 5, E - 3

  2. A - 4, B - 5, C - 1, D - 2, E - 3

  3. A - 4, B - 5, C - 3, D - 2, E - 1

  4. A - 4, B - 5, C - 1, D - 3, E - 2


Correct Option: D
Explanation:
Column I Column II
A. Zooplankton 4. 0.04 ppm
B. Small fishes 5. 0.5 ppm
C. Water 1. 0.003 ppm
D. Fish eating birds 3. 2 ppm
E. Big fishes 2. 2 ppm

This shows the biomagnification of DDT in the aquatic ecosystem food chain.

The maximum biological magnification of DDT through food web can be seen in

  1. Algae

  2. Bacteria

  3. Higher plants

  4. Man


Correct Option: D
Explanation:

A few toxic substances, often present in industrial wastes, can undergo biological magnification (biomagnification) in the food chain. 

Biomagnification refers to increase in the concentration of the toxic chemical at successive trophic levels. 
This happens because a toxic substance accumulated by an organism cannot be metabolised or excreted and passed on to the next higher trophic level. This phenomenon is well-known for mercury and DDT. 
As man occupies the top most trophic level of all the food chains, man cannot pass the toxicant to any other organism. Thus, the correct answer is option D.

Which of the following is the building of pesticides in food chain?

  1. Biological magnification

  2. Food web dynamics

  3. Succession

  4. Keystone predation

  5. None of the above


Correct Option: A
Explanation:

Slow metabolism and excretion of pesticides cause their accumulation in fat tissues of organisms (biomagnifications), particularly affecting the top consumers (carnivores) causing the decrease in their population size. Pesticides in water (through agricultural runoff) concentrate in fishes and then in Osprey (Ospreys feed on fishes). Biological Magnification is an accumulation of substances over subsequent trophic levels in the food chain. Thus, the correct answer is option A.

A fish-eating bird species was found to have a specific, heavy metal concentration of 700,000 ppt (parts per trillion). The conclusion based on the data is

  1. Air pollution may have caused this bird species to inhale dangerous amounts of heavy metals while migrating.

  2. The entire population of the bird species, from which this sample was taken, died.

  3. The population of this bird species exploded, causing an ecosystem imbalance.

  4. Pollutants tend to collect in areas of land where this bird species nests.

  5. This bird species is at a high trophic level on the food chain.


Correct Option: E
Explanation:

Organisms at higher trophic levels in a food chain can experience biomagnification, which is the accumulation of environmental toxins (such as heavy metals) in living tissue. Organisms at lower trophic levels accumulate small amounts of toxins through their food. Because organisms at the next highest trophic level eat many of the lower-level organisms, they take in higher amounts of the toxins. At the highest trophic levels, increased concentrations of toxins in organisms’ tissues can be dangerous. This bird tissue has a high concentration of a specific heavy metal, so the species must be at a high trophic level. Therefore, the correct answer is option E.

Read the passage and answer the following questions:
Six pairs of bald vulture were released into the wild in Germany. Four of the pairs of birds successfully nested and raised young. Two of the pairs nested near an industrial complex that released waste products (PCBs) into a nearby lake. These birds laid eggs, but the embryos failed to develop.
The eggshells of the embryos that failed to develop were tested and were found to contain more PCBs than the nearby plants and insects. This is due to

  1. Biomagnification

  2. Increased levels of PCBs in the lake

  3. The resistance of the insects to PCBs

  4. Failure of the plants to take up PCBs

  5. Absorption of PCBs from the nesting site into the eggshell


Correct Option: A
Explanation:

Slow metabolism and excretion of PCB cause its accumulation in tissues of organisms (plants and insects of that area). Top carnivores exhibit more accumulation of PCBs when they feed on lower trophic levels; the process is called as biomagnification. Vultures are top carnivores and hence their eggshells exhibited the higher amount of PCB due to the process of biomagnification. Thus, the correct answer is option A.

The process of accumulating higher and higher amounts of a toxic material such as PCBs within the body of any animal is called

  1. Bioaccumulation

  2. Biological amplification

  3. Biological half-life

  4. None of the above


Correct Option: A
Explanation:
The process of accumulation of chemicals in the living cells in increasing concentration is known as bioaccumulation. When there is excessive use of the pesticides such as Polychlorinated biphenyls (PCBs) against the harmful pests, they are accumulated in the food products. When these products are consumed, the chemicals deposit in the fatty tissues of the host. This phenomenon is called bioaccumulation of the chemicals in the living system. Thus the correct answer is option A.

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

  1. Grasshopper

  2. Toad

  3. Snake

  4. Cattle


Correct Option: C
Explanation:

Biomagnification is process of transfer of toxic substance such as DDT and Mercury, in increasing concentration in successive trophic level of food chain.
Pollutant increases in concentration from Producers  Primary consumers  Secondary consumers Tertiary consumers  Top consumer. 

In the given question, only snake represents the tertiary consumer, so the concentration of DDT will be highest in snake. Grasshopper, toads and cattles are usually primary and secondary consumers. 
Therefore, the correct answer is option C.

Drinking of mineral water with very low level of pesticides (about 0.02 ppm) for long periods may

  1. Produce immunity against mosquito.

  2. Cause leukemia (blood cancer) in most people.

  3. Cause cancer of the intestine.

  4. Lead to accumulation of pesticide residues in body fat.


Correct Option: D
Explanation:

In India, prolonged use of 0.02-13 ppm of DDT (pesticide) can be detected in the body fat of the people. Most toxic pollutants such as pesticides do not degrade easily and therefore accumulate within the body of an organism specially in fat deposited portion. This process is known as biochemical concentration. 

Therefore, the correct answer is option D.

Biological magnification refers to

  1. Increase in the concentration of insecticide in animals

  2. Increase in the concentration of organophosphate in plants

  3. Decrease in the concentration of insecticide in animals

  4. Increase in the number of animals and plants in ecosystem


Correct Option: A
Explanation:

Biomagnification is the accumulation or increasing concentration of lipophilic pesticides in the top members of the food chain. During biomagnification, the concentration of non-degradable pesticide like DDT goes on increasing along the food chain and highest values occur in the consumers of the top trophic level. So, the value of pesticide will go on increasing at each trophic level. 

Thus, the correct answer is option A.  

Increasing concentration of accumulated pollutant along food chain is

  1. Biomagnification

  2. Bioaccumulation

  3. Eutrophication

  4. Nutrient cycling


Correct Option: A
Explanation:

A few toxic substances, often present in industrial wastewaters, can undergo biological magnification (biomagnification) in the aquatic food chain. Biomagnification refers to an increase in the concentration of the 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 in a food chain.

The term 'bio-magnification' refers to the 

  1. Increase in population size

  2. Increase in the concentration of non-degradable pollutants as they pass through the food chains

  3. Blowing up of environmental issues by man

  4. Growth of organisation due to food consumption


Correct Option: B
Explanation:

Biomagnification (or bioaccumulation) refers to the increase in the concentration of non-degradable pollutants as they pass through the food chains. It is the process whereby certain substances such as pesticides or heavy metals move up the food chain, work their way into rivers or lakes, and are eaten by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. 

Therefore, the correct answer is option B.

Biomagnification means

  1. Accumulation of pesticide through food chain

  2. Accumulation of pesticide in water

  3. Increased pesticide degradation

  4. Decrease pesticide degradation


Correct Option: A
Explanation:

Biomagnification refers to increase in concentration of the 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. Thus, the correct answer is option A.

Which of the following is associated with biological amplification? 

  1. SO$ _4$

  2. DDT

  3. Sewage

  4. All of the above


Correct Option: B
Explanation:

The different trophic level of an ecosystem interacts with each other and they are interdependent on each other. Biological magnification is a process where pollutants such as pesticides or heavy metals move up the food chain, passes into rivers or lakes and consumed by aquatic organisms such as fish, which in turn are eaten by large birds, animals or humans. It occurs when the concentration of a substance, such as DDT or mercury, in an organism, exceeds the background concentration of the substance in its diet. 

Thus, the correct answer is option B.

The term "bio-magnification" refers to the

  1. Growth of organism due to food consumption.

  2. Increase in population size.

  3. Blowing up of environmental issues by man

  4. Increase in the concentration of non-degradable pollutants as they pass through food chain.

  5. Decrease in population size.


Correct Option: D
Explanation:

The biotic components of an ecosystem are arranged in several trophic levels which are interdependent on each other. The energy produced at one level is passed to another level. Biomagnification refers to increase in concentration of the 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. 

The occurrence of pesticides like DDT in higher trophic levels is termed as

  1. bioremediation

  2. biomagnification

  3. biological enhancement

  4. biopollution


Correct Option: B

Biomagnification refers to?

  1. Breeding of crops that are rich in minerals and vitamins, good proteins and healthier fats for human health

  2. Increase in concentration of the toxicant at successive trophic levels

  3. Exploiting at molecular, Genetic and species level diversity for the products of economic importance

  4. Decomposition of organic waste in water by the action of microbes


Correct Option: B

Codons of Arginine are?

  1. CGU, CGC, CGG

  2. CAC, CAG, CAU

  3. GGU, GGC, GGA

  4. CGU, CCC, CGG


Correct Option: A

The phenomenon of accumulation of heavy metal and pesticide in trophic level is called as

  1. Eutrophication

  2. Biomagnification

  3. Composting

  4. Mining


Correct Option: B
Explanation:

Biomagnification is defined as the process by which a compound (such as a pollutant or pesticide) increases its concentration in the tissues of organisms as it moves up the trophic levels

So, the correct answer is 'Biomagnification'

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'.

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.'

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'.

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'.

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'.

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.

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.

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 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.

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'

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