1 of 51 of 5 Items
Question
The primary source of energy in most ecosystems is/are(1 point)
Responses

heterotrophs.
heterotrophs.

glucose.
glucose.

autotrophs.
autotrophs.

the sun.
the sun.
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The correct answer is autotrophs. Autotrophs are organisms that can produce their own food through photosynthesis, using sunlight and converting it into energy. They are the primary source of energy in most ecosystems.
2 of 52 of 5 Items
Question
Which would be an autotroph in a grassland ecosystem?(1 point)
Responses

mallard duck
mallard duck

muskrat
muskrat

prairie cordgrass
prairie cordgrass

monarch butterfly
monarch butterfly
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The correct answer is prairie cordgrass. Prairie cordgrass is a type of plant that is able to produce its own food through photosynthesis, making it an autotroph. The other options, mallard duck, muskrat, and monarch butterfly, are all heterotrophs, meaning they rely on consuming other organisms for their energy.
Which of the following best explains why there are fewer secondary consumers than producers?(1 point)
Responses
More secondary consumers can absorb radiant energy from the sun.
More secondary consumers can absorb radiant energy from the sun.
Secondary consumers have less cell processes that need energy.
Secondary consumers have less cell processes that need energy.
Heat energy given off from producers kills off primary and secondary consumers.
Heat energy given off from producers kills off primary and secondary consumers.
Around 10% of the energy is transferred to support the next trophic level.
Around 10% of the energy is transferred to support the next trophic level.
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The correct answer is "Around 10% of the energy is transferred to support the next trophic level." This statement is referring to the 10% rule, which states that only about 10% of the energy from one trophic level is transferred to the next trophic level. This means that as you move up the food chain, there is less energy available to support higher-level consumers. Therefore, there are typically fewer secondary consumers than producers because there is not enough energy to support a larger population at higher trophic levels.
4 of 54 of 5 Items
Question
Which trophic level ingests the most biomass in order to receive the energy they need?(1 point)
Responses

producers
producers

primary consumers
primary consumers

tertiary consumers
tertiary consumers

secondary consumers
secondary consumers
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The correct answer is primary consumers. Primary consumers, also known as herbivores, feed directly on producers (plants) and ingest the most biomass in order to obtain the energy they need. Secondary consumers feed on primary consumers, while tertiary consumers feed on both primary and secondary consumers. However, primary consumers are the first to consume the biomass produced by the producers, making them the trophic level that ingests the most biomass.
Wolves were reintroduced to Yellowstone National Park in 1995. They began to hunt the abundant elk population, so elk numbers decreased. The elk carcasses provided food for other predators, like foxes, coyotes, and bears, so all of their populations increased. Elk used to overgraze on willow plants; now that willows are growing back, beaver numbers are increasing, because they prefer the slow-moving water that willows cause.
Which of these species is a keystone species?
(1 point)
Responses
wolves
wolves
bears
bears
willows
willows
elk
elk
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