Our Environment Test

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Our Environment Test - 15

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Weekly Quiz Competition

Question 1
1 / -0

In a polluted environment, the maximum concentration of a pollutant will be found in:

A
Primary producers

B
Tertiary consumers

C
Secondary Consumers

D
Primary consumers

Solution

Biomagnification refers to the increase in the concentration of non-degradable pollutants or toxic substances at successive trophic levels in a food chain. This happens when a toxic substance consumed by the organisms of a trophic level cannot be metabolized. When these organisms are consumed by the organisms of higher trophic levels, the toxic substance is passed on to the next higher trophic level. The amount of the toxic substance thus keeps on increasing in successive trophic levels. So, the amount of these substances will be the highest in the organism/s at the topmost trophic level.
Since tertiary consumers usually occupy the topmost trophic level in a food chain, therefore, option B is the correct answer.
Question 2
1 / -0

In a food chain, at each trophic level, the total energy:

A
Increases

B
Decreases

C
Stays the same

D
Cannot be estimated

Solution

Energy flow in an ecosystem is always unidirectional i.e., from the Sun to producers to herbivores to carnivores. It cannot pass in the reverse direction.
There is a decrease in content and flow of energy with the rise in trophic levels. Only 10 percent energy of producers is available to the herbivores for their life processes and then only 10 percent of the herbivore productivity is utilized by carnivores. At each trophic level, the rest of the energy is utilized in metabolic activities and lost as heat during the process of respiration. Therefore, the correct answer is option B.
Question 3
1 / -0

A considerable part of harmful ultraviolet radiation from the sun does not reach the surface of the earth. This is because high above the earth's atmosphere is a layer of ---------.

A
Carbon dioxide

B
Hydrogen

C
Ozone

D
Nitrogen
Solution
- The presence of the layer of ozone (trioxygen) prevents the UV rays from reaching the surface of the earth.
- The reactions that occurs to form ozone from oxygen are shown below:
$$O_{2}\overset{h\nu}{\rightarrow} [O] + [O]$$
$$O_{2} + [O]\overset{h\nu}{\rightarrow} O_{3}$$

Thus, the correct answer is option C.
Question 4
1 / -0

The presence of which of the following gases in air checks the ultraviolet rays from sunlight?

A
SO$$_{2}$$

B
CO$$_{2}$$

C
NO

D
O$$_{3}$$

Solution

At the higher levels of the atmosphere, ozone(O$$_3$$) performs an essential function. It shields the surface of the Earth from ultraviolet (UV) radiation from the sun. This radiation is highly damaging to organisms, for example, it is known to cause skin cancer in human beings.
Hence, option D is correct.
Question 5
1 / -0

The trophic level of a bamboo plant growing in a forest is at ________ level.

A
First

B
Second

C
Third

D
Fourth

Solution

The trophic level of an organism is the position it occupies in the food chain, a food web or an ecological pyramid. Producers belong to the first trophic level, herbivores to the second trophic level, and carnivores to the third trophic level. Thus, the bamboo plant which is a producer will belong to the first trophic level.
Thus, the correct answer is option A.
Question 6
1 / -0

Increase in the concentration of pollutants (toxicant) in higher trophic levels is called:

A
Recycling

B
Eutrophication

C
Biodegradation

D
Biomagnification

Solution

Persistent pesticides e.g., organochlorines or chlorinated hydrocarbons, like DDT, pass into the food chain and increase in the amount per unit weight of organisms with the rise in trophic level due to their accumulation in tissues of animals. This phenomenon is called biomagnification.
So, the correct answer is 'D'.
Question 7
1 / -0

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

A
Algae

B
Bacteria

C
Higher plants

D
Man

Solution

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.
Question 8
1 / -0

Which of the following is an artificial ecosystem?

A
Rice-field

B
Forest

C
Grassland

D
Lake

Solution

Rice-field is an artificial ecosystem because the fields are grown by men for agricultural needs. They do not occur naturally that is why it an artificial ecosystem.
Question 9
1 / -0

Which of the following describes a food chain?

A
Large number of animals competing for a source of food.

B
Transfer of food energy from the green plants through a series of consumer organisms.

C
Transfer of chemicals from one trophic level to another.

D
None of the above
Solution
- A food chain is defined as a linear network of links in a food web starting from producer organisms and ending at an apex predator species, or decomposer species.
- Green plants are known as producers as they trap energy from the sun and then pass it to all the consumers occupying successive trophic levels.
Therefore, the correct answer is option B.
Question 10
1 / -0

Biological equilibrium is found among the

A
Producer plants

B
Consumers and producers

C
Decomposers

D
Producers, consumers and decomposers

Solution

A food chain has several trophic levels where each trophic level is dependent on the other for energy. This interdependence maintains a biological equilibrium in the ecosystem. The various levels are as followed-
1) Producers make their own food which is passed on to the next trophic level. Example-plants.
2) Primary Consumers- It depends on the producers. Example-rabbit.
3) Secondary consumers- It depends on the primary consumer for energy. Example- bear
4) Tertiary consumer-It depends on the secondary consumers for the food. Example- Eagle
5) Decomposers decompose the dead and decaying material into humus which enriches the soil. Example- bacteria.

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Re-Attempt Weekly Quiz Competition

Our Environment Test - 15

Result

Our Environment Test - 15

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SHARING IS CARING

Question 1

Primary producers

Tertiary consumers

Secondary Consumers

Primary consumers

Solution

Question 2

Increases

Decreases

Stays the same

Cannot be estimated

Solution

Question 3

Carbon dioxide

Hydrogen

Ozone

Nitrogen

Solution

Question 4

SO$$_{2}$$

CO$$_{2}$$

NO

O$$_{3}$$

Solution

Question 5

First

Second

Third

Fourth

Solution

Question 6

Recycling

Eutrophication

Biodegradation

Biomagnification

Solution

Question 7

Algae

Bacteria

Higher plants

Man

Solution

Question 8

Rice-field

Forest

Grassland

Lake

Solution

Question 9

Large number of animals competing for a source of food.

Transfer of food energy from the green plants through a series of consumer organisms.

Transfer of chemicals from one trophic level to another.

None of the above

Solution

Question 10

Producer plants

Consumers and producers

Decomposers

Producers, consumers and decomposers

Solution

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