1. The primary source of energy in most ecosystems is/are
A. autotrophs

B. the sun

C. heterotrophs

D. glucose

2. Which would be an autotroph in a grassland ecosystem?
A. mallard duck

B. prairie cordgrass

C. monarch butterfly

D. muskrat

3. Which of the following best explains why there are fewer secondary consumers than producers?
A. Around 10% of the energy is transferred to support the next trophic level.

B. Heat energy given off from producers kills off primary and secondary consumers.

C. Secondary consumers have less cell processes that need energy.

D. More secondary consumers can absorb radiant energy from the sun.

4. Which tropic level ingests the most biomass in order to receive the energy they need?
A. primary consumers

B. producers

C. tertiary consumers

D. secondary consumers

5. 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?
A. willows

B. elk

C. bears

D. wolves

3) The statement that best explains why there are fewer secondary consumers than producers is; Option A; Around 10% of the energy is transferred to support the next trophic level.

4) The tropic level that ingests the most biomass in order to receive the energy they need is; Option C; Tertiary Consumers

5) The species among the given ones that is a keystone specie is;

Option D; Wolves

1) The primary source of energy in virtually all ecosystems is solar energy from the sun. This solar energy is used by photoautotrophs to prepare food. Meanwhile all other organisms are usually dependent on autotrophs for their food.

2) An autotroph is defined as an organism that can produce its own food using light, water, carbon dioxide e.t.c. Therefore, they are called called producers. The only autotroph in the options is Prairie Cordgrass.

3) There are fewer secondary consumers than primary consumers due to the fact that for secondary consumers to be alive, they need to eat a lot of primary consumers. Thus, it means a percentage of the energy which is believed to be around 10% is transferred to support the next autotrophic level.

4) From the given options, the trophic level that ingests the most biomass in order to receive the energy they need is called Tertiary consumers.

5) A keystone specie is a type of specie defined as an organism that helps to determine an eco system. Which means if it is taken out of an eco system, all others are affected. In this example given, the keystone specie is clearly Wolves.

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