Energy Flow and Trophic Levels in Ecological Pyramids

Ecological pyramids illustrate feeding relationships, energy flow, and population numbers in ecosystems. The base, formed by autotrophs, supports all other levels by converting sunlight into chemical energy. Energy flows from autotrophs to herbivores and then to carnivores, with each trophic level decreasing in size and energy availability. Ecosystem stability requires more producers than consumers. Energy is lost as heat, with only 10% transferred to the next level. The sun provides a continuous energy input, sustaining ecosystems.

What is the primary role of autotrophs in an ecosystem?

• To decompose organic matter

• To provide the original source of chemical energy

• To act as secondary consumers

• To consume other organisms

What is the significance of the base of an ecological pyramid?

• It is the smallest level

• It supports all other levels

• It represents the top predators

• It is where energy is lost as heat

Which of the following best describes secondary consumers?

• Organisms that produce their own food

• Decomposers that break down dead matter

• Herbivores that eat plants

• Carnivorous species that eat other animals

What is the role of tertiary consumers in an ecosystem?

• They decompose organic matter

• They are primary producers

• They are the top predators in the food chain

• They produce energy for the ecosystem

What is a key characteristic of a stable ecosystem?

• More carnivores than herbivores

• Equal numbers of producers and consumers

• More producers than consumers

• More tertiary consumers than secondary consumers

Why must there be more plants than herbivores in an ecosystem?

• To provide sufficient energy for herbivores

• To prevent overpopulation of plants

• To maintain a balance in the food chain

• To ensure enough oxygen is produced

How much energy is typically transferred from one trophic level to the next?

• 50%

• 25%

• 10%

• 90%

What happens to most of the energy obtained by an organism?

• It is transferred to the next trophic level

• It is used to perform life functions and lost as heat

• It is stored as fat

• It is converted into biomass

How is an ecosystem sustained despite constant energy loss?

• Through the recycling of nutrients

• By the continual input of energy from the sun

• By increasing the number of consumers

• Through the accumulation of energy at the top of the pyramid

What is the main source of energy for autotrophs?

• Light energy from the sun

• Heat from the environment

• Nutrients from the soil

• Chemical energy from other organisms