Ecology Summative Study Guide

Explain the principle of energy transfer between trophic levels in an ecosystem.

• Energy transfer is 100% efficient between trophic levels.

• Only 10% of energy is transferred from one trophic level to the next.

• Energy is lost entirely during transfer between trophic levels.

• Energy transfer does not occur in ecosystems.

Answer explanation

In ecosystems, energy transfer between trophic levels is inefficient, with only about 10% of energy being passed on to the next level. The rest is lost as heat and through metabolic processes.

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What is the difference between a biotic factor and an abiotic factor? Provide one example of each.

• Biotic factors are non-living, while abiotic factors are living.

• Biotic factors are living or once-living, while abiotic factors are non-living.

• Biotic factors are chemical components, while abiotic factors are physical components.

• Biotic factors are only plants, while abiotic factors are only rocks.

Answer explanation

Biotic factors are living or once-living organisms, such as plants and animals, while abiotic factors are non-living elements like water and rocks. This distinction is crucial for understanding ecosystems.

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Define the term 'producer' and explain which member of a food chain has the most available sunlight energy.

• Producers are organisms that consume other organisms; primary consumers have the most sunlight energy.

• Producers are organisms that create their own food; producers have the most sunlight energy.

• Producers are organisms that decompose organic matter; decomposers have the most sunlight energy.

• Producers are organisms that hunt prey; apex predators have the most sunlight energy.

Answer explanation

Producers are organisms that create their own food through photosynthesis, using sunlight energy. Therefore, they have the most available sunlight energy in a food chain, unlike consumers or decomposers.

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Describe the symbiotic relationship of mutualism using the example of lichen.

• Mutualism is a relationship where one organism benefits and the other is harmed; lichen is an example.

• Mutualism is a relationship where both organisms benefit; lichen is an example.

• Mutualism is a relationship where one organism benefits and the other is unaffected; lichen is an example.

• Mutualism is a relationship where both organisms are harmed; lichen is an example.

Answer explanation

Mutualism is a symbiotic relationship where both organisms benefit. In the case of lichen, the fungus provides structure and protection, while the algae or cyanobacteria conduct photosynthesis, supplying nutrients. Thus, both thrive.

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What is a 'limiting factor'? Explain how temperature can act as one.

• A limiting factor is something that increases population growth; temperature always increases growth.

• A limiting factor is something that restricts population growth; temperature can restrict growth.

• A limiting factor is something that has no effect on population growth; temperature is irrelevant.

• A limiting factor is something that eliminates populations entirely; temperature always eliminates populations.

Answer explanation

A limiting factor restricts population growth, meaning it can prevent a population from increasing indefinitely. Temperature can limit growth by affecting survival, reproduction, and resource availability, making the correct choice accurate.

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What is a producer in an ecosystem?

• An organism that feeds on other organisms

• An organism that creates its own food through photosynthesis

• An organism that breaks down dead organic material

• An organism that lives at the top of the food chain

Answer explanation

A producer in an ecosystem is an organism that creates its own food through photosynthesis, such as plants. This distinguishes them from consumers, which feed on other organisms, and decomposers, which break down dead material.

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What is mutualism in ecological relationships?

• A relationship where one organism benefits and the other is harmed

• A relationship where two organisms live together and both benefit

• A relationship where one organism feeds on another

• A relationship where organisms compete for resources

Answer explanation

Mutualism is a type of ecological relationship where two organisms live together and both benefit from the interaction. This distinguishes it from other relationships like parasitism or competition.

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What is a limiting factor in an ecosystem?

• A factor that increases the population size

• A factor that restricts the size or growth of a population

• A factor that provides food for predators

• A factor that enhances the availability of sunlight

Answer explanation

A limiting factor in an ecosystem is a factor that restricts the size or growth of a population. This can include resources like food, water, and space, which can limit how many individuals can survive and reproduce.

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What is the role of decomposers in an ecosystem?

• They create their own food through photosynthesis

• They feed on other organisms

• They break down dead organic material and return nutrients to the soil

• They live at the top of the food chain

Answer explanation

Decomposers play a crucial role in ecosystems by breaking down dead organic material, which recycles nutrients back into the soil, supporting plant growth and maintaining ecological balance.

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What is an apex predator?

• An organism that feeds on producers

• An organism that breaks down organic material

• A predator at the top of the food chain without natural predators of its own

• An organism that creates its own food through photosynthesis

Answer explanation

An apex predator is defined as a predator at the top of the food chain that has no natural predators of its own, making it a key species in maintaining the balance of its ecosystem.

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