Ecosystem Test

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Ecosystem Test - 40

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Weekly Quiz Competition

Question 1
1 / -0

Read the passage and answer the following question.

Vegetation follows established patterns of regrowth and change after disturbances by farming, timber harvesting, hurricanes, or fire. This process of patterned regrowth and change is called plant succession. The rate of succession and the species present at various stages depending on the type and degrees of disturbance, the environment of the particular sites, and the species available to occupy the site. In the Piedmont of North Carolina, land subjected to disturbances will grow back in a century or two to become mixed hardwood forest.

Based on this diagram, after 80 years, which will make up the majority of trees?

A
Young pines

B
Mature pines

C
Oat trees

D
Oat and hickory trees

E
Pine, oak and hickory trees

Solution

According to the given diagram, the 70th to 100th year will exhibit a transition from Pine to the hardwood community. The 80th year will have mix vegetation of Pine, Oak, and hickory forest and after 100 plus years, Pine will disappear leading to the formation of climax community i.e. Oak hickory forest. Thus, the correct answer is option D.
Question 2
1 / -0

In ecological succession,

A
Pioneer species move into new communities first

B
Climax communities have lower total biomass than preceding communities

C
Species diversity is greatest in the early stages of succession

D
Climax communities shift constantly

E
All of the above
Solution
Correct Option: A

Explanation:
Ecological succession is the process of gradual change in the species structure of an ecological community over time.
Pioneer species are the species that are first to colonize an area and begin a chain of ecological succession that ultimately leads to a more biodiverse steady-state ecosystem.
Plants that are first to invade the bare area are called pioneer species, e.g., lichens (succession on rocks).
Thus, the correct answer is the option 'Pioneer species move into new communities first'.
Question 3
1 / -0

The least amount of stored chemical energy is found in which of the following trophic level?

A
Primary producers

B
Decomposers

C
Primary consumers

D
Secondary consumers

E
Tertiary consumers
Question 4
1 / -0

The amount of energy get reduce as it moves from producers to primary consumers because

A
Saprophytic activity

B
Biomass decreases

C
Secondary consumers eat primary consumers

D
Respiration and metabolic activity

E
None of the above

Solution
Question 5
1 / -0

In an ecosystem undergoing succession, replacement of a plant community takes place due to

A
Pollution

B
Herbivory

C
Parasitism

D
Abiotic factors

E
Intraspecific competition

Solution

In an ecosystem undergoing succession, replacement of a plant community takes place due to abiotic factors. Ecological succession is the observed as the process of gradual change in an ecological community over time.
Abiotic factors are the non-living things in an ecosystem like water depth, pH, sunlight, turbidity (amount of water cloudiness), salinity (salt concentration), available nutrients (nitrogen, phosphorous, etc.), and dissolved oxygen (amount of oxygen dissolved in the water). Abiotic variables found in terrestrial ecosystems can include things like rain, wind, temperature, altitude, soil, pollution, nutrients, pH, types of soil, and sunlight.
So, the correct answer is option D.
Question 6
1 / -0

Which of the following explains stable ecosystem?

A
Requires a constant energy source

B
Requires a living system

C
Is self-sustaining

D
Requires cycling of materials between the living system and the environment

E
All of the above
Question 7
1 / -0

What change would take place in the given ecosystem with time?

A
The herbivores will decline because there is not enough food to support them.

B
The herbivores will increase and the secondary customers increase.

C
The population of producers, herbivores and carnivores will remain the same.

D
The secondary customers will decline and the producers will increase.

E
The producers will increase to support the herbivores.

Solution

In given ecological pyramid, the population of producers is less as compare to Herbivores. Once herbivores start consuming producers which includes plants, the population of producers will decrease and it will creates competition between herbivores which ultimately leads to decline in population of Herbivores as there is not enough food to support them. Hence, the correct answer is option A.
Question 8
1 / -0

The diagram above shows an ecological pyramid of net productivity that describes the multiplicative loss of energy in a food chain. Each trophic level in the food chain is represented by a bar in the pyramid, with primary producers forming the foundation of the pyramid. The size of each block represents the productivity at each trophic level per unit of time.
In the above example, approximately how much energy available in each trophic level is converted into new biomass in the trophic level above it?

A
$1$ %

B
$5$ %

C
$10$ %

D
$50$ %

E
$100$ %

Solution

The diagrams show ecological pyramid, it is graphically represented to show the biomass or productivity of the biomass at each trophic level in an ecosystem.
According to ten percent law, during the transfer of energy from organic food from one trophic level to the next, only about ten percent of the energy is transferred from one trophic level to another. The remaining is lost during transfer, broken down in respiration, or lost to incomplete digestion by higher trophic levels. In the example given, as 10000J of energy is produced by producers, but only 1,000J is transferred to primary consumers and same way only 100J is transferred to secondary consumers. Hence, the correct answer is option C.
Question 9
1 / -0

Select the correct statement about succession.

A
All farm ponds will eventually fill in and dry up.

B
Secondary succession involves the formation of dirt and soil.

C
Climax communities are not subject to change.

D
Random events play little, if any, part in succession.

E
In temperate deciduous forests, oaks and hickories are replaced by pines and furs.

Solution

All farm ponds will eventually fill in and dry up.
Ecological succession is the process of change in the species structure of an ecological community over time. The time scale can be decades (for example, after a wildfire), or even millions of years after a mass extinction.
Ecological succession, the process by which the structure of a biological community evolves over time. Two different types of succession—primary and secondary—have been distinguished. Primary succession occurs in essentially lifeless areas—regions in which the soil is incapable of sustaining life as a result of such factors as lava flows, newly formed sand dunes, or rocks left from a retreating glacier. Secondary succession occurs in areas where a community that previously existed has been removed; it is typified by smaller-scale disturbances that do not eliminate all life and nutrients from the environment.
Question 10
1 / -0

Which of the following processes is responsible for the existence of a stream free of pollutants within a few miles downstream of a point at which a small amount of sewage is dumped into it?

A
Succession

B
Biological magnification

C
Evaporation

D
Photosynthesis

E
Decomposition

Solution

The presence of decomposers (bacteria) in sewage leads to decomposition of complex organic compounds of sewage into simpler substances. These simpler substances are then consumed by the decomposers as a source of organic compounds. This led to the formation of pollution free stream out of a sewage dump. Thus, the correct answer is option E.

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Ecosystem Test - 40

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Ecosystem Test - 40

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Question 1

Young pines

Mature pines

Oat trees

Oat and hickory trees

Pine, oak and hickory trees

Solution

Question 2

Pioneer species move into new communities first

Climax communities have lower total biomass than preceding communities

Species diversity is greatest in the early stages of succession

Climax communities shift constantly

All of the above

Solution

Question 3

Primary producers

Decomposers

Primary consumers

Secondary consumers

Tertiary consumers

Question 4

Saprophytic activity

Biomass decreases

Secondary consumers eat primary consumers

Respiration and metabolic activity

None of the above

Solution

Question 5

Pollution

Herbivory

Parasitism

Abiotic factors

Intraspecific competition

Solution

Question 6

Requires a constant energy source

Requires a living system

Is self-sustaining

Requires cycling of materials between the living system and the environment

All of the above

Question 7

The herbivores will decline because there is not enough food to support them.

The herbivores will increase and the secondary customers increase.

The population of producers, herbivores and carnivores will remain the same.

The secondary customers will decline and the producers will increase.

The producers will increase to support the herbivores.

Solution

Question 8

111%

555%

101010%

505050%

100100100%

Solution

Question 9

All farm ponds will eventually fill in and dry up.

Secondary succession involves the formation of dirt and soil.

Climax communities are not subject to change.

Random events play little, if any, part in succession.

In temperate deciduous forests, oaks and hickories are replaced by pines and furs.

Solution

Question 10

Succession

Biological magnification

Evaporation

Photosynthesis

Decomposition

Solution

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$1$ %

$5$ %

$10$ %

$50$ %

$100$ %