Question

1. think about the flow of matter and energy in a pyramid model with a producer level, a primary consumer level, a secondary consumer level, and a tertiary consumer level. select all correct answers.

a) the sun is the ultimate source of energy in an ecosystem.
b) matter flows and is often conserved within or among ecosystems.
c) energy flows through ecosystems, but only a certain amount of energy is transformed into biomass.
d) energy flows through ecosystems, but some is lost to the environment as heat.
e) matter and energy are completely conserved and transformed into biomass within an ecosystem.

1. what is the relationship between a food chain and trophic levels?

a) a food chain demonstrates how the organisms at the highest trophic levels have the most energy.
b) food chains illustrate the flow of energy from one trophic level to the next.
c) a food chain models the energy flow within a single trophic level.

1. in a trophic pyramid the primary consumers have 1500 j of food energy. how much of that energy will be transferred to the secondary consumers?

Explanation:

• Question 3:
• Option A: The sun is indeed the ultimate energy source for most ecosystems as producers (like plants) use solar energy for photosynthesis.
• Option B: Matter is recycled and conserved within and among ecosystems through biogeochemical cycles (e.g., carbon, nitrogen cycles).
• Option C: Energy flows through ecosystems (producer → primary consumer → secondary consumer etc.), and only a portion (about 10 - 20% in a simple energy transfer model) is converted into biomass (new body mass of the consumer).
• Option D: Energy transfer is not 100% efficient. Some energy is lost as heat (due to metabolic processes like respiration) at each trophic level.
• Option E: Energy is not completely conserved as biomass within an ecosystem because of energy losses as heat. Matter is conserved (as per the law of conservation of mass), but the statement about energy is incorrect.
• Question 4:
• Option A: Organisms at the highest trophic levels have the least energy (due to energy loss at each transfer, following the 10% rule).
• Option B: Food chains show the linear flow of energy from one trophic level (e.g., producer) to the next (e.g., primary consumer).
• Option C: A food chain shows energy flow across trophic levels, not within a single trophic level.

Answer:

• Question 3: A. The sun is the ultimate source of energy in an ecosystem; B. Matter flows and is often conserved within or among ecosystems; C. Energy flows through ecosystems, but only a certain amount of energy is transformed into biomass; D. Energy flows through ecosystems, but some is lost to the environment as heat.
• Question 4: B. Food chains illustrate the flow of energy from one trophic level to the next.