Question 1

The law of conservation of matter states that matter cannot be created, yet matter is sometimes gained or lost to an ecosystem. What is the reason for this seeming contradiction?
A)Chemoautotrophic organisms can convert matter to energy.
B)Matter can be moved in/out of an ecosystem from/to another ecosystem.
C)Photosynthetic organisms convert solar energy to sugars.
D)Detrivores convert matter to energy.
E)Heterotrophs convert heat to energy.

Accepted Answer

While matter cannot be created or destroyed within an ecosystem, it can be transferred from one ecosystem to another, or in and out of an ecosystem through various means such as wind, water, or human activity. This can lead to apparent gains or losses of matter within a given ecosystem, but in reality, the overall amount of matter remains constant.

Question 2

Which of these ecosystems accounts for the largest amount of Earth's net primary productivity?
A)tundra
B)savanna
C)salt marsh
D)open ocean
E)tropical rain forest

Accepted Answer

D

Question 3

Which of the following is an example of an ecosystem?
A)all of the brook trout in a 500 hectare² river drainage system
B)the plants, animals, and decomposers that inhabit an alpine meadow
C)a pond and all of the plant and animal species that live in it
D)the intricate interactions of the various plant and animal species on a savanna during a drought
E)interactions between all of the organisms and their physical environment in a tropical rain forest

Accepted Answer

An ecosystem includes all the interactions between organisms and their physical environment, making option E the correct example of an ecosystem.

Question 4

To recycle nutrients, an ecosystem must have, at a minimum,
A)producers.
B)producers and decomposers.
C)producers, primary consumers, and decomposers.
D)producers, primary consumers, secondary consumers, and decomposers.
E)producers, primary consumers, secondary consumers, top carnivores, and decomposers.

Accepted Answer

In order to recycle nutrients, the ecosystem needs both producers and decomposers. Producers (usually plants) take inorganic nutrients from the environment and convert them into organic compounds through photosynthesis. Decomposers (usually bacteria and fungi) break down dead organic matter and release the nutrients back into the ecosystem, making them available for use by producers once again. Without decomposers, nutrients would become locked up in dead organic matter and unavailable to other organisms. Primary consumers (herbivores), secondary consumers (carnivores), top carnivores, and other trophic levels are important for ecosystem functioning, but are not strictly necessary for nutrient recycling.

Question 5

Which of the following terms encompasses all of the others?
A)heterotrophs
B)herbivores
C)carnivores
D)primary consumers
E)secondary consumers

Accepted Answer

Heterotrophs include all organisms that obtain their energy from consuming other organisms. Herbivores, carnivores, primary consumers, and secondary consumers are all types of heterotrophs, but not all heterotrophs fit into these specific categories (e.g. omnivores).

Question 6

Which of the following is true of detrivores?
A)They recycle chemical elements directly back to primary consumers.
B)They synthesize organic molecules that are used by primary producers.
C)They convert organic materials from all trophic levels to inorganic compounds usable by primary producers.
D)They secrete enzymes that convert the organic molecules of detritus into CO₂ and H₂O.
E)Some species are autotrophic, while others are heterotrophic.

Accepted Answer

Detrivores are organisms that obtain their energy and nutrients by consuming dead organic matter, such as fallen leaves or dead animals. They break down this organic material into inorganic compounds, which can then be used by primary producers to synthesize new organic matter. Therefore, detrivores convert organic materials from all trophic levels to inorganic compounds usable by primary producers.

Question 7

Decomposers obtain energy from
A)live organic material
B)detritus
C)fungi
D)other heterotrophs
E)bacteria

Accepted Answer

Decomposers obtain energy from detritus, which consists of dead organic material and waste products.

Question 8

What percentage of solar radiation striking a plant is converted into chemical energy?
A)1%
B)10%
C)25%
D)50%
E)100%

Accepted Answer

Only about 1% of the solar radiation that hits a plant is converted into chemical energy through the process of photosynthesis. The majority of sunlight is either reflected, transmitted, or absorbed but not used for photosynthesis.

Question 9

Photosynthetic organisms are unique to most ecosystems because they
A)synthesize organic compounds they obtain from decaying heterotrophs.
B)synthesize inorganic compounds from organic compounds.
C)use light energy to synthesize organic compounds.
D)use chemical energy to synthesize organic compounds.
E)convert light energy into matter.

Accepted Answer

Photosynthetic organisms use light energy to convert inorganic compounds (carbon dioxide and water) into organic compounds (like glucose) through the process of photosynthesis. This unique ability to produce their own food from sunlight and simple chemicals sets them apart from other organisms in most ecosystems.

Question 10

Gross primary production
A)is equal to NPP - respiration of autotrophs.
B)is about half of NPP.
C)is the total biomass of all photosynthetic autotrophs.
D)is the total energy from light converted to chemical energy of organic molecules per unit time.
E)is not as important as net primary production.

Accepted Answer

Gross primary production (GPP) is the total amount of organic matter produced by plants through photosynthesis in a given area and time period. It is expressed in units of energy per unit area per unit time (e.g., kJ/m2/year). GPP includes the energy produced during photosynthesis that is consumed during plant respiration (R), referred to as autotrophic respiration. Therefore, the net primary production (NPP) is equal to GPP minus R. Hence, option A is incorrect. GPP is greater than NPP because GPP includes the energy that is lost in R. Therefore, option B is incorrect. GPP includes the organic material produced by all photosynthetic autotrophs, including microscopic algae, rooted submerged aquatic plants, and emergent plants, in addition to herbaceous and woody plants. Therefore, option C is incorrect. GPP is a critical component of the carbon cycle and serves as the foundation for all trophic processes in ecosystems. Thus, it is essential for understanding ecosystem functioning and productivity. Thus, option E is incorrect.

Question 11

How do the Taylor Glacier bacteria produce their energy?
A)photosynthesis
B)heterotrophism
C)chemoautotrophism
D)thermophobism
E)chemosynthesis

Accepted Answer

The Taylor Glacier bacteria produce their energy through chemoautotrophism, which is a type of metabolism that uses inorganic compounds as a source of energy and carbon dioxide as a source of carbon to produce organic molecules. This allows the bacteria to survive in extreme environments where other energy sources may not be available.

Question 12

In ecosystems, why is the term cycling used to describe material transfer, whereas the term flow is used for energy exchange?
A)Materials are repeatedly used, but energy flows through and out of ecosystems.
B)Both material and energy are recycled and are then transferred to other ecosystems as in a flow.
C)Materials are cycled into ecosystems from other ecosystems, but energy constantly flows within the ecosystem.
D)Both material and energy flow in a never-ending stream within an ecosystem.
E)None of the choices is correct.

Accepted Answer

Material cycling refers to the repeated use and transfer of nutrients and other organic and inorganic compounds within ecosystems, while energy flow refers to the ongoing exchange of energy between organisms and their environment. Energy is not recycled in the same way that materials are, as it continuously enters ecosystems from the sun and is eventually lost as heat. Therefore, the term cycling is more appropriate for material transfer, while flow accurately describes energy exchange.

Question 13

Which statement most accurately describes how matter and energy are used in ecosystems?
A)Matter is cycled through ecosystems; energy is not.
B)Energy is cycled through ecosystems; matter is not.
C)Energy can be converted into matter; matter cannot be converted into energy.
D)Matter can be converted into energy; energy cannot be converted into matter.
E)Matter is used in ecosystems; energy is not.

Accepted Answer

Matter is constantly being recycled in ecosystems through processes such as the water cycle and nutrient cycling, while energy flows through ecosystems and is not recycled.

Question 14

If the sun were to suddenly stop providing energy to Earth, most ecosystems would vanish. Which of the following ecosystems would likely survive the longest after this hypothetical disaster?
A)tropical rain forest
B)tundra
C)benthic ocean
D)grassland
E)desert

Accepted Answer

The benthic ocean, which is the ocean floor, is home to organisms that rely on chemosynthesis rather than photosynthesis to produce energy. Chemosynthetic bacteria get their energy from chemicals released from hydrothermal vents on the ocean floor, so they would be able to survive without the sun's energy. Other ecosystems rely on the sun's energy to produce food through photosynthesis, so they would be affected more quickly.

Question 15

Many homeowners mow their lawns during the summer and collect the clippings, which are then hauled to the local landfill. Which of the following actions would most benefit the suburban ecosystem?
A)Allow sheep to graze the lawn and then collect the sheep's feces to be delivered to the landfill.
B)Collect the lawn clippings and burn them.
C)Collect the lawn clippings and add them to a compost pile, don't collect the clippings and let them decompose into the lawn, or apply composted clippings to the lawn.
D)Collect the clippings and wash them into the nearest storm sewer that feeds into the local lake.
E)Dig up the lawn and cover the yard with asphalt.

Accepted Answer

Collecting the lawn clippings and adding them to a compost pile or applying composted clippings to the lawn can benefit the suburban ecosystem in several ways. Firstly, it can reduce the amount of waste that is hauled to the landfill, which can help reduce greenhouse gas emissions from the landfill. Secondly, adding organic matter to the soil through composting can improve soil health and fertility, which can benefit plant growth and reduce the need for synthetic fertilizers. Finally, allowing the clippings to decompose into the lawn can provide valuable nutrients to the soil and promote healthy plant growth.

Question 16

A cow's herbivorous diet indicates that it is a(n)
A)primary consumer.
B)secondary consumer.
C)decomposer.
D)autotroph.
E)producer.

Accepted Answer

A herbivorous diet means the cow only eats plants and is therefore a primary consumer, which means it eats producers (plants) as its main source of food.

Question 17

Subtraction of which of the following will convert gross primary productivity into net primary productivity?
A)the energy contained in the standing crop
B)the energy used by heterotrophs in respiration
C)the energy used by autotrophs in respiration
D)the energy fixed by photosynthesis
E)all solar energy

Accepted Answer

Net primary productivity (NPP) is the gross primary productivity (GPP) minus the energy used by autotrophs in respiration. Therefore, subtracting the energy used by autotrophs in respiration will convert GPP into NPP.

Question 18

Approximately 1% of the solar radiation that strikes a plant is converted into the chemical bond energy of sugars. Why is this amount so low?
A)Approximately 99% of the solar radiation is converted to heat energy.
B)Only 1% of the wavelengths of visible light are absorbed by photosynthetic pigments.
C)Most solar energy strikes water and land surfaces.
D)Approximately 99% of the solar radiation is reflected.
E)Only the green wavelengths are absorbed by plants for photosynthesis.

Accepted Answer

Only a small percentage of wavelengths in the visible light spectrum are absorbed by photosynthetic pigments such as chlorophyll. This limits the amount of solar radiation that can be converted into chemical energy by plants.

Question 19

The major role of detrivores in ecosystems is to
A)provide a nutritional resource for heterotrophs.
B)recycle chemical nutrients to a form capable of being used by autotrophs.
C)prevent the buildup of the organic remains of organisms, feces, and so on.
D)return energy lost to the ecosystem by other organisms.

Accepted Answer

Detrivores play a crucial role in the ecosystem's nutrient cycling. They decompose organic matter into simpler inorganic compounds, releasing nutrients like nitrogen, phosphorus, and carbon, that can be taken up by autotrophs to synthesize organic matter. Therefore, they recycle chemical nutrients to a form capable of being used by autotrophs.

Question 20

What are two key factors controlling primary productivity in lakes and oceans?
A)light and nutrients
B)nutrients and temperature
C)light and temperature
D)light and phytoplankton
E)nutrients and wind

Accepted Answer

The two key factors controlling primary productivity in lakes and oceans are light and nutrients. Light is necessary for photosynthesis, while nutrients such as nitrogen and phosphorus are required for the growth and reproduction of primary producers such as phytoplankton. Temperature and wind can also impact primary productivity, but they are not considered the primary factors controlling it.

Quiz 55: Ecosystems and Restoration Ecology

The law of conservation of matter states that matter cannot be created, yet matter is sometimes gained or lost to an ecosystem. What is the reason for this seeming contradiction?

Which of these ecosystems accounts for the largest amount of Earth's net primary productivity?

Which of the following is an example of an ecosystem?

To recycle nutrients, an ecosystem must have, at a minimum,

Which of the following terms encompasses all of the others?

Which of the following is true of detrivores?

Decomposers obtain energy from

What percentage of solar radiation striking a plant is converted into chemical energy?

Photosynthetic organisms are unique to most ecosystems because they

Gross primary production

How do the Taylor Glacier bacteria produce their energy?

In ecosystems, why is the term cycling used to describe material transfer, whereas the term flow is used for energy exchange?

Which statement most accurately describes how matter and energy are used in ecosystems?

If the sun were to suddenly stop providing energy to Earth, most ecosystems would vanish. Which of the following ecosystems would likely survive the longest after this hypothetical disaster?

Many homeowners mow their lawns during the summer and collect the clippings, which are then hauled to the local landfill. Which of the following actions would most benefit the suburban ecosystem?

A cow's herbivorous diet indicates that it is a(n)

Subtraction of which of the following will convert gross primary productivity into net primary productivity?

Approximately 1% of the solar radiation that strikes a plant is converted into the chemical bond energy of sugars. Why is this amount so low?

The major role of detrivores in ecosystems is to

What are two key factors controlling primary productivity in lakes and oceans?