Ecosystem Test

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Ecosystem Test - 79

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Weekly Quiz Competition

Question 1
1 / -0

In a food chain, if the grasses produce 1000 kcal of energy, how many kcal are theoretically available to the frogs?

A
1000

B
100

C
10

D
1

E
0.5

Solution

When energy is passed in an ecosystem from one trophic level to the next, only ten percent (10%) of the energy will be passed on. We can consider a typical food chain in the environment. It can be written as follows. Sun -----> Green Plants -----> Insects -----> Frogs -----> Snakes. The sun provides the energy that is used by the green plants. The green plants are the primary producers for the food chain. The energy from the sun is converted by the plants into food. The insects are the primary consumers. They are the first animals to eat the plants. When they eat the plants and obtain some of the energy (10%) they stored when making food. The rest of the energy is lost and dissipated as heat. Insects are eaten by frogs. The frogs are the secondary consumers in this food chain. They obtain part of the energy stored by the insects. The remaining energy stored by the insects is lost. Thus, the correct answer is option C.
Question 2
1 / -0

For a stable lake ecosystem, the net primary production (NPP) is equal to the

A
Phytoplankton present in the photic zone

B
Phytoplankton consumed by heterotrophs

C
Dissolved nutrients used by phytoplankton

D
Dissolved oxygen used by phytoplankton

E
Dissolved oxygen used by all consumers

Solution

Net Primary Productivity (NPP) is the amount of carbon uptake after subtracting Plant Respiration (RES) from Gross Primary Productivity (GPP). NPP is not equal to the total biomass of producers, but to the amount of biomass that is added. In a stable lake, the added phytoplankton biomass will equal that consumed by zooplankton.
Therefore, the correct answer is option B.
Question 3
1 / -0

The data given in the table shows species richness of mosses, shrubs and trees calculated for one hectare $$(10,000 m^2)$$ of land every 50 years for 200 years based on a long running ecological study.
Year Mosses Shrubs Trees
1800 16 2 0
1850 21 7 4
1900 10 5 3
1950 13 12 6
2000 17 28 14
The ecological process occurring according to the data is

A
Evolution

B
Succession

C
Destabilization

D
Primary growth

E
Artificial selection

Solution

The process of change in ecological community of an area over time which in turn results in the formation of climax community is termed as succession. The direction and predictable change in the community lead to alteration of the environment. Now the changing environment leads to altered species composition and structure. In given data, the year 1800 has only mosses and shrubs and with the passage of time, the number of shrubs and tree species increased.
Therefore, the correct answer is option B.
Question 4
1 / -0

A stable lake ecosystem shows net primary production which is equal to the

A
Phytoplankton present in the photic zone

B
Phytoplankton consumed by heterotrophs

C
Dissolved nutrients used by phytoplankton

D
Dissolved oxygen used by phytoplankton

E
Dissolved oxygen used by all consumers

Solution

Phytoplankton are the primary producers of stable lake ecosystem and total phytoplankton present in photic zone represent the gross primary production i.e. total organic matter produced per unit area. Phytoplanktons consumed by heterotrophs represent net primary production which is calculated by the difference between gross primary production and organic matter consumed in respiration. Dissolved oxygen is not representative of primary productivity. Thus, the correct answer is B.
Question 5
1 / -0

Choose the correct statement regarding ecological succession.

A
It is a natural progression of plant types that cannot be reversed.

B
It always occurs over a short period time.

C
The rate can be changed by factors such as fire, clear cutting, and lava flows.

D
It only takes place on freshly cleared or new land such as islands.

E
The rate is very slow and constant.

Solution

The process of change in ecological community of an area over time which in turn results in the formation of climax community is termed as succession. The direction and predictable change in the community lead to alteration of the environment. Now the changing environment leads to altered species composition and structure. it can occur on a bare land (primary succession) or in the area where vegetation was removed by any climatic or anthropogenic factor (secondary succession). It is a long and slow but dynamic process in which changes in climatic conditions can reverse the plant types. Any natural or anthropogenic calamity can further hinder or increase its rate. For example, flooding, fire, deforestation can damage the existing vegetation and need the process to start again.
Therefore, the correct answer is option C.
Question 6
1 / -0

The study of a pond revealed the presence of skimmers and minnows in it. Which of the following process is responsible for the conversion of pond into a swampy land after 15 years showing the prevalence of frogs and snakes?

A
Predation

B
Succession

C
Speciation

D
Natural disaster

E
Global warming

Question 7

1 / -0

Read the passage and answer the following question.

A population study of plants was done in an abandoned field. Each year for $$3$$ years the vegetation was sampled. The chart indicates the results of the body.

Year		Number of Plants per Acre
	Sandspur	Ragweed	Timothy Grass	Goldenrod	Wire Grass
$$1$$	$$3,800$$	$$4,900$$	$$600$$	$$0$$	$$412$$
$$2$$	$$1,500$$	$$2,209$$	$$1,185$$	$$75$$	$$796$$
$$3$$	$$752$$	$$180$$	$$2,234$$	$$790$$	$$1,643$$$

Which of the following are initially most successful in succession?

Sandspur and ragweed

Sandspur and timothy grass

Ragweed and timothy grass

Ragweed and wire grass

Sandspur and goldenrod

Solution

In the initial, the most successful plants in the succession is Sandspur and Ragweed with 3,800 and 4,900 plants per acre in the first year.

Question 8
1 / -0

According to the theories of succession, what will be the result?

A
The lake will get deeper and the trees more numerous

B
The lake will get shallower and the trees will be replaced by grass

C
The lake will dry up

D
The trees will become coniferous types

E
There is no fixed order to the replacement of species

Solution

Ecological succession is the gradual process by which ecosystems, change and develop over time. These series of environmental changes that take place in the ecosystem are two main types- primary and secondary. However, the stages that each ecosystem passes through during succession is predictable. The given diagram represents an ecological succession of Lakes. Ponds and Lakes are the habitats for many plants, insects, fish and birds. while there is life underneath the water bodies the shore line is also a thriving place for may plants and trees as the water line recedes and the faunal living space is increased and diversified. at the climax succession, these lake bodies are surrounded by forest trees. While the increase in the temperature around the lakes leads to higher precipitation from the water bodies, the materials from erosion of watershed and plants and animals existing in the ecosystem tend to fill the lakes and ponds over time resulting in the lakes drying up.
Question 9
1 / -0

Which one of the following is true for a climax community?

A
The nitrogen cycle ceases to be important for primary producers.

B
There are no changes in seasonal population sizes in the community.

C
Predator-prey relationships between trophic levels in the food web remain constant from one generation to the next.

D
There is no loss of energy from one trophic level to the next.

E
There is only one species of primary producer.
Question 10
1 / -0

Which of the following is true about climax community?

A
Consists of only one species of life

B
Is populated mainly by so-called pioneer organisms

C
Is stable within a given climate

D
Is independent of the environment

E
Consists of decaying organic matter
Solution
- The climax community is the final community that develops at the end of biotic succession.
- It is stable.
- It has maximum diversity.
- So, the correct answer is option C.

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Year	Mosses	Shrubs	Trees
1800	16	2	0
1850	21	7	4
1900	10	5	3
1950	13	12	6
2000	17	28	14

Ecosystem Test - 79

Result

Ecosystem Test - 79

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SHARING IS CARING

Question 1

1000

100

10

1

0.5

Solution

Question 2

Phytoplankton present in the photic zone

Phytoplankton consumed by heterotrophs

Dissolved nutrients used by phytoplankton

Dissolved oxygen used by phytoplankton

Dissolved oxygen used by all consumers

Solution

Question 3

Evolution

Succession

Destabilization

Primary growth

Artificial selection

Solution

Question 4

Phytoplankton present in the photic zone

Phytoplankton consumed by heterotrophs

Dissolved nutrients used by phytoplankton

Dissolved oxygen used by phytoplankton

Dissolved oxygen used by all consumers

Solution

Question 5

It is a natural progression of plant types that cannot be reversed.

It always occurs over a short period time.

The rate can be changed by factors such as fire, clear cutting, and lava flows.

It only takes place on freshly cleared or new land such as islands.

The rate is very slow and constant.

Solution

Question 6

Predation

Succession

Speciation

Natural disaster

Global warming

Question 7

Sandspur and ragweed

Sandspur and timothy grass

Ragweed and timothy grass

Ragweed and wire grass

Sandspur and goldenrod

Solution

Question 8

The lake will get deeper and the trees more numerous

The lake will get shallower and the trees will be replaced by grass

The lake will dry up

The trees will become coniferous types

There is no fixed order to the replacement of species

Solution

Question 9

The nitrogen cycle ceases to be important for primary producers.

There are no changes in seasonal population sizes in the community.

Predator-prey relationships between trophic levels in the food web remain constant from one generation to the next.

There is no loss of energy from one trophic level to the next.

There is only one species of primary producer.

Question 10

Consists of only one species of life

Is populated mainly by so-called pioneer organisms

Is stable within a given climate

Is independent of the environment

Consists of decaying organic matter

Solution

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