Energy metabolism — Identify the single false statement (others are true with proper wording and scope).
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AThe energy that powers most living systems on Earth ultimately originates from the sun
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BAll animals ultimately depend on primary producers (such as plants or algae) for chemical energy flow in their food webs
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CPlants provide the water and carbon dioxide that animals need to carry out respiration
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DMost eukaryotic cells generate ATP via aerobic respiration in mitochondria when oxygen is available
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EDecomposers recycle nutrients but do not create new energy; energy flows and is lost as heat
Answer
Correct Answer: Plants provide the water and carbon dioxide that animals need to carry out respiration
Explanation
Introduction / Context:This concept question integrates ecology and physiology. It asks you to distinguish accurate generalizations about energy flow and respiration from a deliberately incorrect statement about the gases used by animals during cellular respiration.
Given Data / Assumptions:
- Energy for nearly all ecosystems is solar in origin, captured by photosynthesis.
- Animals are heterotrophs; their energy comes from organic matter originating from primary producers (plants, algae, some bacteria).
- Aerobic respiration uses O2 as the terminal electron acceptor and produces CO2 and water as products.
Concept / Approach:Evaluate each statement using core principles. The false statement should attribute the wrong gases to animal respiration requirements. Animals require O2, not CO2, to carry out aerobic respiration; they release CO2. The other statements are broadly true with proper scope qualifiers (for example, “most” or “ultimately”).
Step-by-Step Solution:
Check (a): Primary energy source for Earth’s biosphere is the sun → broadly true.Check (b): Food chains originate with primary producers → true as a general rule.Check (c): Claims animals need CO2 for respiration → false; animals need O2 and produce CO2.Check (d): Aerobic respiration in eukaryotes occurs in mitochondria → true when O2 is present.Check (e): Consistent with thermodynamics in ecosystems → true.Verification / Alternative check:Basic physiology confirms that hemoglobin transports O2 to tissues; mitochondria consume O2 and generate CO2 via the TCA cycle and pyruvate oxidation.
Why Other Options Are Wrong:
a) Correct—photosynthesis captures solar energy that fuels ecosystems.b) Correct—animals depend on producer biomass directly or indirectly.d) Correct—many eukaryotes respire aerobically when oxygen is available.e) Correct—decomposers recycle matter; energy is dissipated as heat.Common Pitfalls:Confusing animal respiration with plant gas exchange; both use O2 in mitochondria, but plants also produce O2 in photosynthesis.
Final Answer:Plants do not provide CO2 for animal respiration; animals require O2 and produce CO2, so option (c) is false.