Question 1

The major role of detritivores in ecosystems is to

Accepted Answer

Detritivores break down dead organic matter, recycling nutrients back into the ecosystem, making them available for autotrophs (like plants) to use.

Question 2

Which of the following refers to the amount of new biomass added in a given period of time?

Accepted Answer

Net primary productivity refers to the amount of new biomass added in a given period of time by only primary producers (like plants). It is measured by subtracting the amount of energy that the primary producers use themselves (respiration) from the amount of energy they produce through photosynthesis.

Question 3

Which of the following is an example of an ecosystem?

Accepted Answer

E

Question 4

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

Accepted Answer

A cow's consumption of plants makes it a primary consumer, as it is directly consuming producers (plants). Secondary consumers would consume other consumers, such as carnivores that eat other herbivores. Chemotrophic animals obtain energy through chemical reactions, while autotrophic animals are able to produce their own energy through photosynthesis or chemosynthesis. Primary producers are plants or other organisms that produce their own energy through photosynthesis or chemosynthesis.

Question 5

How is it that the open ocean produces the highest net primary productivity of Earth's ecosystems,yet net primary productivity per square meter is relatively low?

Accepted Answer

The open ocean has the highest net primary productivity because it covers the largest area of any ecosystem on Earth, allowing for a vast total production despite having a low productivity per unit area.

Question 6

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?

Accepted Answer

Only a small portion of the electromagnetic spectrum can be absorbed and utilized by photosynthetic pigments, specifically the red and blue wavelengths. The majority of solar energy is in the form of visible light, but not all of it is useful for photosynthesis. Therefore, only a small fraction of the solar radiation that strikes a plant is converted into chemical bond energy of sugars.

Question 7

Which of these ecosystems has the highest net primary productivity per square meter annually?

Accepted Answer

The Amazon rainforest is known for its incredibly high net primary productivity due to its warm, moist climate and high levels of biodiversity. It is estimated that the Amazon rainforest produces around 2,200 grams of biomass per square meter annually.

Question 8

What percentage of visible light striking a plant is converted into chemical energy?

Accepted Answer

Only about 1% of the visible light striking a plant is converted into chemical energy through the process of photosynthesis.

Question 9

The availability of soil nutrients has a direct effect on primary productivity.Which of the following is most correct regarding non-limiting and limiting nutrients?

Accepted Answer

Nitrogen is often the most common limiting nutrient in many ecosystems, particularly on a global scale, affecting the rate of primary production.

Question 10

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

Accepted Answer

Gross primary productivity is the rate at which producers convert solar energy into chemical energy through photosynthesis, but some of this energy is used by the producers themselves during respiration. Net primary productivity is the rate at which producers store energy as biomass, and it is calculated by subtracting the energy used by producers in respiration (choice C) from gross primary productivity. The other choices (A, B, D, E) are not relevant to this calculation.

Question 11

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

Accepted Answer

The Pacific open ocean accounts for the largest amount of Earth's net primary productivity due to its vast size. Despite having a lower productivity per square meter compared to some terrestrial ecosystems, the immense area of the open ocean makes its total contribution to global net primary productivity the highest.

Question 12

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

Accepted Answer

Ecosystems are open systems, meaning that matter can be gained or lost to them through inputs and outputs. While matter cannot be created or destroyed within a closed system, it can be moved between ecosystems through processes such as migration, decomposition, and nutrient cycling.

Question 13

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

Accepted Answer

Producers are essential for the production of organic matter through the process of photosynthesis. Decomposers break down organic matter into inorganic nutrients that can be taken up by producers, so they play a critical role in the recycling of nutrients. While primary consumers can also contribute to the recycling of nutrients by excreting waste that contains nutrients, they are not strictly necessary for the process. Similarly, secondary consumers and top carnivores are not necessary for nutrient recycling, as they do not contribute organic matter back into the ecosystem in the same way that producers and decomposers do. Therefore, the minimum requirement for nutrient recycling is producers and decomposers.

Question 14

Scientists use trophic cycles to study the flow of matter in an ecosystem by observing feeding relationships between organisms.Which of the following statements is most correct regarding the terminology used in trophic cycles?

Accepted Answer

Carnivores are considered heterotrophs because they obtain their energy from consuming other organisms. Autotrophs, on the other hand, are organisms that can produce their own energy through photosynthesis or chemosynthesis. Herbivores are organisms that feed on plants and are considered primary consumers. Primary producers are autotrophs that produce organic matter from inorganic substances. Therefore, labeling an omnivore as a heterotroph or saying that autotrophs can be labeled as primary consumers is incorrect.

Question 15

Which of the following is most correct regarding the activity of detritivores?

Accepted Answer

Detritivores are organisms that feed on dead or decaying organic matter. Their activity involves converting organic matter into inorganic matter, such as nutrients and minerals, which are then used by primary producers to create new organic matter. Therefore, option B is the most correct.

Question 16

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?

Accepted Answer

The Pacific deep-sea vent ecosystem relies on chemosynthesis instead of photosynthesis for its energy source, making it the most likely to survive without the sun's energy. The other ecosystems listed all depend on photosynthesis to some degree and would not be able to survive without the sun.

Question 17

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

Accepted Answer

Chemical elements, such as carbon and nitrogen, are reused and recycled within ecosystems. This means that they are cycled between different organisms and the environment. Energy, on the other hand, is constantly flowing through ecosystems and cannot be reused or recycled. It enters as sunlight and exits as heat. Therefore, the term cycling is used for chemical elements and the term flow is used for energy exchange.

Question 18

Photosynthetic organisms are unique to most ecosystems because they

Accepted Answer

Photosynthetic organisms use light energy to convert inorganic matter (such as carbon dioxide and water) into organic matter (such as glucose) through the process of photosynthesis. This ability sets them apart from other organisms that rely on obtaining organic matter from consuming other organisms.

Question 19

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

Accepted Answer

Energy enters ecosystems as sunlight and flows through the food chain, being transferred from one organism to another. Eventually, most of the energy is converted into heat and lost from the ecosystem. Matter, on the other hand, is constantly cycled within and through ecosystems, being taken up by organisms, incorporated into their tissues, and then released back into the environment through processes such as respiration, excretion, and decomposition. This cycling of matter is essential for the maintenance and growth of living organisms in ecosystems.

Question 20

Primary producers support the primary consumers in an ecosystem.Which of the following is most correct regarding primary producers?

Accepted Answer

Primary producers are organisms that produce biomass from inorganic compounds. In ecosystems around deep-sea vents, chemoautotrophic prokaryotes use chemical energy from hydrothermal vents to fix carbon, making them primary producers.

Quiz 42: Ecosystems and Energy