Ecosystem Test

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Ecosystem Test - 83

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Weekly Quiz Competition

Question 1
1 / -0

Main objective of production of herbicide resistant GM crops is to

A
Encourage eco-friendly herbicides

B
Reduce herbicide accumulation in food articles for health safety

C
Eliminate weeds from the field without the use of manual labour

D
Eliminate weeds from the field without the use of herbicides.

Solution

Weeds such as String decrease crop yields and quality by competing with crop plants for light, water and nutrients. Weeds are to be removed with the help of herbicide (weed killer). Herbicide tolerance has been developed in maize, cotton, soybean, tobacco, etc. The main aim is to reduce herbicide accumulation in food products for health safety.
Question 2
1 / -0

The mean biomass per unit area and the net primary productivity for four ecosystems P, Q, R and S are tabulated.
Ecosystem Mean biomass per unit area (kg $$m^{-2}$$) Net primary productivity (g $$m^{-2}yr^{-1}$$)
P $$1.6$$ $$500$$
Q $$2.0$$ $$2000$$
R $$44$$ $$2000$$
S $$0.67$$ $$71$$

The four ecosystems most likely could be.

A
P: Tropical rainforest, Q: Temperate grassland, R: Desert, S: Algal bed

B
P: Desert, Q: Tropical rainforest, R: Temperate grassland, S: Algal bed

C
P: Algal bed, Q: Temperate grassland, R: Tropical rainforest, S: Desert

D
P: Temperate grassland, Q: Algal bed, R: Tropical rainforest, S: Desert

Solution

Net primary productivity is the amount of carbon used after respiration from gross primary productivity. Based on net primary productivity, ecosystems may be grouped into following types:
1. High productive ecosystems: Net productivity is about 2000-4000 g m⁻² yr⁻¹. For example, tropical rainforests, coral reefs, estuaries etc.
2. Average productive ecosystems: Net productivity is about 1000-2000 g m⁻² yr⁻¹ with a daily output of 3-5 g m⁻². For example, temperate forests.
3. Less productive ecosystems: Net productivity is about 200-1000 g m⁻² yr⁻¹ with a daily output of about 0.5-3.0 g m⁻². For example, grassland ecosystems and savanna.
4. Low productive ecosystems: Net productivity is less than 200 g m⁻² yr⁻¹ . For example, desserts.
Based on this data, P should be temperate grassland , Q should be algal bed, R should be tropical rainforest and S should be desert.
NPP for both Q and R is same i.e., 2000 g m⁻² yr⁻¹ since the mean biomass is more for R, it indicates that R is tropical rainforests as these are the most productive ecosystems.
So, the correct answer is D.
Question 3
1 / -0

Which of the following fish led to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the take Victoria of E. Africa?

A
Catla catla

B
Dog fish

C
Nile perch

D
African catfish

Solution

Nile perch, (species Lates niloticus), large food and game fish of the family Centropomidae (order Perciformes), found in the Nile and other rivers and lakes of Africa. A large-mouthed fish, the Nile perch is greenish or brownish above and silvery below and grows to about 1.8 m (6 feet) and 140 kg (300 pounds). It has an elongated body, a protruding lower jaw, a rounded tail, and two dorsal fins. In 1954, L. niloticus was introduced into Lake Victoria in Africa, home to hundreds of cichlid fishes. A powerful predator, the Nile perch has greatly reduced the cichlid numbers.
So the correct option is 'nile perch'.
Question 4
1 / -0

The annual net primary productivity of the whole biosphere is approximately.

A
$$150$$ billion tons

B
$$160$$ billion tons

C
$$170$$ billion tons

D
$$180$$ billion tons

Solution

The annual net primary productivity of the whole biosphere is approximately $$170$$ billion tons. Out of this, oceans contribute $$55$$ billion tons.

Question 5

1 / -0

During the stages of succession in a given ecosystem, the following changes in characteristics may be observed.

	Characteristic	Stages in ecosystem development	Stages in ecosystem development
		Early	Late
A.	Total organic matter	Low	High
B.	Species diversity	Low	High
C.	Size of organism	Small	Large
D.	Productivity	Low	High
E.	Food chains	Short	Long

Which one of the characteristics, A, B, C, D or E is responsible for the apparent high degree of stability associated with a climax ecosystem?

B

D

A

E

Solution

Climax ecosystem is a biological community for species which through the process of succession have developed in an area over time, have reached a community of species that are relatively stable in its composition and biomass.

So the correct option is 'B'.

Question 6
1 / -0

The biomass available for consumption to heterotrophs and the rate of formation of new organic matter by consumers are defined as

A
Gross primary productivity and Net primary productivity respectively

B
Net primary productivity and Gross primary productivity respectively

C
Gross primary productivity and Secondary productivity resectively

D
Net primary productivity and Secondary productivity respectively
Solution
- Gross Primary Production, GPP, is the total amount of CO$$_2$$ that is fixed by the plant in photosynthesis.
- Respiration (R) is the amount of CO$$_2$$ that is lost from an organism or system from metabolic activity.
- Net Primary Production (NPP) is the net amount of primary production after the costs of plant respiration are included. Therefore, NPP = GPP - R.
- It is the amount of energy that a plant stores as biomass, which is then available to heterotrophs.
- Primary productivity is the rate of formation of new organic matter by producers i.e. Plants and other photosynthetic organisms.
- Secondary productivity is the rate of formation of new organic matter by consumers.
So, the correct answer is option D.
Question 7
1 / -0

Which of the following representations show the pyramid of number in a forest ecosystem?

A
D

B
A

C
B

D
C
Solution
An ecological pyramid shows the relationship of biomass, productivity or energy at different trophic levels. The primary producers are generally shown at the bottom and apex predators at the top. The pyramids are different for different ecosystems.
The pyramid of numbers shows the number of individual organisms at successive trophic levels. In a forest ecosystem, the producers are large size trees that make the base of the Pyramid. The herbivores such as fruit-eating birds, deer, elephants, etc. make the primary consumers and are less than primary producers. After that, the number goes down at each successive level. Thus, a Pyramid of numbers in a Forest Ecosystem is partially upright or spindle-shaped. C is Spindle Shaped.
So the correct option is 'D'.
Question 8
1 / -0

Which of the given pyramids represents the variation in biomass at different trophic levels in pond ecosystem?

A

B

C

D

Solution

A.Correct option C

B.Explanation for the correct option:

1. Biomass is the standing amount of weight an area holds of all the organisms with respect to time.

2. Trophic levels are the parameters that define the source through which the producers and consumers acquire their food.

3. Producers are one that is autotrophs. Primary consumers are the herbivore of that ecosystem. Secondary consumers are those that feed upon the primary consumers hence; they follow carnivores’ pattern of feeding.

4. Generally, the pyramid of biomass is upright, but there exists an exception of the pond ecosystem where the pyramid is inverted.

5. In the pond ecosystem the biomass of plants is comparatively less than other trophic level organisms because as we go up the body biomass increases exponentially in this case.
Question 9
1 / -0

In an ecological succession, saprophytes belong to

A
$$T_1$$

B
$$T_2$$

C
Either $$T_2 \, or \, T_3$$

D
None

Solution

In an ecological pyramid, saprophytes are not given any trophic level because they mostly include decomposers that derive nutrition from a dead and decaying matter of plants and animals. The ecological pyramids reveal the interaction between living components of the ecosystem, and since saprophytes interact with dead and decay matter of organisms at all levels, it’s very difficult to assign them any specific trophic level within the ecosystem.
So the correct option is "none".
Question 10
1 / -0

In a pyramid of numbers representing an ecosystem of a large freshwater pond, the number of primary consumers is

A
Less than the top consumers

B
Less than the secondary consumers

C
Less than the producer

D
None of these
Solution
- The number of primary consumers is always less than the producers in a pyramid of numbers that represent an ecosystem with a large freshwater pond. In a large freshwater pond, the producers are always higher in number. The number of primary consumers is less than the producers, and secondary consumers are even less in number. The top consumers in a pond ecosystem are least in number.
So, the correct answer is 'Less than the secondary consumer'.

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Ecosystem	Mean biomass per unit area (kg $$m^{-2}$$)	Net primary productivity (g $$m^{-2}yr^{-1}$$)
P	$$1.6$$	$$500$$
Q	$$2.0$$	$$2000$$
R	$$44$$	$$2000$$
S	$$0.67$$	$$71$$

Ecosystem Test - 83

Result

Ecosystem Test - 83

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Rank

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SHARING IS CARING

Question 1

Encourage eco-friendly herbicides

Reduce herbicide accumulation in food articles for health safety

Eliminate weeds from the field without the use of manual labour

Eliminate weeds from the field without the use of herbicides.

Solution

Question 2

P: Tropical rainforest, Q: Temperate grassland, R: Desert, S: Algal bed

P: Desert, Q: Tropical rainforest, R: Temperate grassland, S: Algal bed

P: Algal bed, Q: Temperate grassland, R: Tropical rainforest, S: Desert

P: Temperate grassland, Q: Algal bed, R: Tropical rainforest, S: Desert

Solution

Question 3

Catla catla

Dog fish

Nile perch

African catfish

Solution

Question 4

$$150$$ billion tons

$$160$$ billion tons

$$170$$ billion tons

$$180$$ billion tons

Solution

Question 5

B

D

A

E

Solution

Question 6

Gross primary productivity and Net primary productivity respectively

Net primary productivity and Gross primary productivity respectively

Gross primary productivity and Secondary productivity resectively

Net primary productivity and Secondary productivity respectively

Solution

Question 7

D

A

B

C

Solution

Question 8

Solution

Question 9

$$T_1$$

$$T_2$$

Either $$T_2 \, or \, T_3$$

None

Solution

Question 10

Less than the top consumers

Less than the secondary consumers

Less than the producer

None of these

Solution

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