Question 1

Which of the following describes the ultimate disposition of most energy in an ecosystem?
A)It is used to construct the bodies of decomposers.
B)It is trapped as fossil fuels when producers die and become fossilized.
C)It is continuously recycled back into the ecosystem.
D)It eventually returns to space in the form of heat.

Accepted Answer

Most of the energy in an ecosystem is eventually lost to the environment as heat, as the second law of thermodynamics states that energy will always flow from hot to cold. This means that energy is continuously transferred from one organism to another but is never recycled back to the ecosystem in a usable form. Instead, it is dissipated as heat energy and eventually released back into space.

Question 2

Net primary productivity in a terrarium could be estimated by
A)carefully controlling the amount of light entering it.
B)counting the change in the number of plant species in it.
C)weighing the terrarium at regular intervals.
D)removing the primary consumers and weighing them at regular intervals.

Accepted Answer

C

Question 3

If there are 50 kcal of energy in the tertiary consumer trophic level, how many kcal would you expect to find in the primary consumer level?
A)50
B)100
C)500
D)5,000

Accepted Answer

D

Question 4

To best use the Earth's NPP to feed the most people, diets should be modified to include _____, and gathering the maximum amount of energy available from a given biomass of producers.
A)only meat, moving higher up the food chain
B)only meat, moving lower down the food chain
C)plant material only, moving lower down the food chain
D)plant material only, moving higher up the food chain

Accepted Answer

Eating lower on the food chain (i.e. consuming plant material directly) is the most efficient way to use the Earth's NPP to feed the most people. This is because at each level of the food chain, energy is lost in the form of heat and metabolic processes, so there is less total energy available to be consumed. Consuming meat, especially from higher up the food chain, requires more energy input and results in less overall food production. Therefore, modifying diets to focus on plant material and moving lower down the food chain is the best choice for feeding the most people using the Earth's NPP.

Question 5

A spacecraft crash lands on an airless, lifeless moon. All that survives, along with the crew, are some chickens, cornflakes, and vitamins. The air and water recyclers are functioning. To maximize their food supply until rescued the crew should
A)feed the cornflakes and vitamins to the chickens, then eat the eggs until rescued.
B)kill all the chickens immediately, eat them first, then eat the cornflakes.
C)mark each week's survival by eating one chicken.
D)ration the chickens first; when they are all eaten, shift to the cornflakes.

Accepted Answer

The answer of A spacecraft crash lands on an airless,...

Question 6

The figure below shows the net primary productivity (NPP)in marine biomes around the world. 
The pattern of NPP in marine ecosystems as shown above suggests that
A)marine productivity is as sensitive to temperature as terrestrial productivity.
B)without shade from overhead vegetation, marine productivity typically exceeds that found in terrestrial ecosystems.
C)marine ecosystems are also limited by sunlight, with the highest productivity at the equator.
D)most marine productivity results from the input of terrestrially derived nutrients.

Accepted Answer

The answer of The figure below shows the net primary...

Question 7

Which of the following statements about cycling within an ecosystem is false?
A)Energy is recycled within an ecosystem.
B)Carbon is recycled within an ecosystem.
C)The sedimentary nutrient cycle cycles nutrients very slowly.
D)Human activities affect nutrient cycling.

Accepted Answer

Energy is not recycled within an ecosystem. It is transferred from one organism to another, but it is eventually lost as heat.

Question 8

The rate of new biomass production by consumers is called
A)primary productivity.
B)a biomass flow chain.
C)an energy pyramid.
D)secondary productivity.

Accepted Answer

The rate of new biomass production by consumers is called secondary productivity. Primary productivity refers to the rate of new biomass production by autotrophs, while a biomass flow chain refers to the flow of energy and nutrients through a trophic level. An energy pyramid is a graphical representation of the energy flow through different trophic levels in an ecosystem.

Question 9

In marine ecosystems, net primary productivity tends to be
A)greater along shorelines where terrestrial nutrients enter the marine environment.
B)lower where the oceans border land because terrestrial pollution suppresses marine productivity.
C)lowest in areas where upwelling brings colder water to the surface.
D)greater than the net primary productivity on land.

Accepted Answer

Terrestrial nutrients, such as from rivers, enhance productivity in coastal areas, leading to higher net primary productivity. Upwelling can also bring nutrients to the surface, increasing productivity in those areas. However, overall productivity in marine ecosystems is generally lower than that of terrestrial ecosystems.

Question 10

In an ecosystem, energy differs from nutrients in that
A)energy is recycled through photosynthesis, but nutrients are recycled through the atmosphere.
B)nutrients are recycled, but energy eventually moves out of the system and is lost.
C)nutrients are recycled through plant roots, but energy is recycled through leaves.
D)energy is recycled by producers, but nutrients are recycled by consumers.

Accepted Answer

Energy flows through an ecosystem, eventually being lost as heat, while nutrients are recycled through various biogeochemical cycles. Nutrients are taken up by producers, passed on to consumers, and eventually decomposed by microorganisms, releasing the nutrients back into the environment to be taken up again. Energy, on the other hand, cannot be recycled in this way and eventually leaves the system.

Question 11

Cougars defend a relatively large territory; consider the following facts and estimate how much area a cougar would require: A cougar requires 490 kg annually and obtains most of its food from deer, which average 55 kg. In a typical deer habitat, the NPP is 35 kg per acre. One deer consumes approximately 1,150 kg of vegetation each year.
A)300 acres
B)1,925 acres
C)3,000 acres
D)4,500 acres

Accepted Answer

The answer of Cougars defend a relatively large territory; consider...

Question 12

What best explains the low productivity of the open ocean?
A)The open ocean lacks insufficient light to support photosynthesis.
B)Nutrients rapidly sink to depths that sunlight cannot reach.
C)The open ocean is actually very productive, but its primary producers are consumed as quickly as they grow.
D)These regions are typically too cool to support significant primary production.

Accepted Answer

Nutrients are quickly sunk to depths beyond the reach of sunlight, limiting the amount of primary production that can occur in the open ocean.

Question 13

On average, what percentage of the energy from one trophic level of an energy pyramid is transferred to the next trophic level?
A)10 percent
B)33 percent
C)50 percent
D)100 percent

Accepted Answer

Only 10 percent of the energy from one trophic level is transferred to the next trophic level due to energy loss in the form of heat, waste, and respiration. This is known as the 10% rule. Therefore, the correct answer is A) 10 percent.

Question 14

Which of the following series best represents the energy flow in an ecosystem?
A)sun → consumer → producer → heat
B)consumer → producer → decomposer → sun
C)producer → consumer → decomposer → sun
D)sun → producer → consumer → heat

Accepted Answer

The answer of Which of the following series best represents...

Question 15

Once an organic molecule enters a metabolic pathway, a significant percentage of its energy
A)can be recycled through the ecosystem.
B)will be recovered and used by decomposers.
C)is lost as unrecoverable heat.
D)enters the nutrient cycle.

Accepted Answer

According to the Second Law of Thermodynamics, energy transformations are not 100% efficient, and a significant amount of energy is lost as unrecoverable heat during metabolic pathways. This energy cannot be recycled through the ecosystem or used by decomposers. Some of the energy may enter the nutrient cycle, but not a significant percentage. Thus, option C is the best choice.

Question 16

Almost all life on Earth is directly or indirectly dependent on
A)predation.
B)solar energy.
C)physical productivity.
D)human civilization.

Accepted Answer

Solar energy is the ultimate source of energy for almost all life on Earth, as it is captured by photosynthetic organisms and transferred through the food chain. Without solar energy, these organisms would not be able to survive and support other forms of life. Predation, physical productivity, and human civilization also play important roles in ecosystems, but they are not as fundamental as the availability of solar energy.

Question 17

Other than the polar tundra, the least productive biomes tend to be
A)deserts.
B)the temperate forests.
C)the tropical forests.
D)estuaries.

Accepted Answer

Deserts are the least productive biomes due to their extreme temperatures, lack of water, and limited nutrient availability. The plants and animals that do exist in deserts have adapted to these harsh conditions, and as a result, the overall productivity of the biome is low compared to other biomes.

Question 18

Which of the following is the dominant type of organism in the two natural terrestrial ecosystems that have the greatest net primary productivity (NPP)?
A)grass
B)trees
C)food crops
D)fish

Accepted Answer

The two natural terrestrial ecosystems with the greatest net primary productivity (NPP) are tropical rainforests and temperate deciduous forests. In both of these ecosystems, trees are the dominant type of organism, contributing significantly to the overall NPP.

Question 19

The marine ecosystem with the lowest net primary productivity is
A)the coral reef.
B)the open ocean.
C)swamp and marsh areas.
D)the ocean upwelling zone.

Accepted Answer

The open ocean has the lowest net primary productivity because it has a low concentration of nutrients, and light can only penetrate the surface layer, making it difficult for photosynthesis to occur further below. The other options have higher net primary productivity due to the availability of nutrients and sunlight.

Question 20

Which of the following would utilize the highest percentage of net primary productivity?
A)producers
B)decomposers
C)herbivores
D)predators

Accepted Answer

Decomposers utilize a high percentage of net primary productivity as they break down dead organic matter, recycling nutrients back into the ecosystem.

Quiz 24: Ecosystems

Which of the following describes the ultimate disposition of most energy in an ecosystem?

Net primary productivity in a terrarium could be estimated by

If there are 50 kcal of energy in the tertiary consumer trophic level, how many kcal would you expect to find in the primary consumer level?

To best use the Earth's NPP to feed the most people, diets should be modified to include _____, and gathering the maximum amount of energy available from a given biomass of producers.

A spacecraft crash lands on an airless, lifeless moon. All that survives, along with the crew, are some chickens, cornflakes, and vitamins. The air and water recyclers are functioning. To maximize their food supply until rescued the crew should

The figure below shows the net primary productivity (NPP) in marine biomes around the world. The pattern of NPP in marine ecosystems as shown above suggests that

Which of the following statements about cycling within an ecosystem is false?

The rate of new biomass production by consumers is called

In marine ecosystems, net primary productivity tends to be

In an ecosystem, energy differs from nutrients in that

What best explains the low productivity of the open ocean?

On average, what percentage of the energy from one trophic level of an energy pyramid is transferred to the next trophic level?

Which of the following series best represents the energy flow in an ecosystem?

Once an organic molecule enters a metabolic pathway, a significant percentage of its energy

Almost all life on Earth is directly or indirectly dependent on

Other than the polar tundra, the least productive biomes tend to be

Which of the following is the dominant type of organism in the two natural terrestrial ecosystems that have the greatest net primary productivity (NPP) ?

The marine ecosystem with the lowest net primary productivity is

Which of the following would utilize the highest percentage of net primary productivity?