Biology Ecosystems and Energy Flow Flashcards
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Read the first 7 Biology Ecosystems and Energy Flow flashcards as text
If a grassland ecosystem has 10,000 kcal available at the producer level, approximately how many kcal are available to secondary consumers, assuming 10% efficiency at each transfer?
Answer: 100 kcal
At 10% efficiency, 10,000 kcal → 1,000 kcal (primary consumers) → 100 kcal (secondary consumers).
Mutualistic mycorrhizal fungi associated with plant roots primarily benefit the plant by:
Answer: Increasing the plant's ability to absorb water and phosphorus
Mycorrhizal fungi greatly extend the root surface area, enhancing uptake of water and minerals, especially phosphorus, in exchange for plant carbohydrates.
Which of the following best illustrates a bottom-up trophic cascade?
Answer: Fertilizer runoff increases algae growth, which supports more fish
A bottom-up cascade starts at the producer level; nutrient addition boosts primary producers, increasing biomass at each successive trophic level.
In the phosphorus cycle, which reservoir contains the largest amount of phosphorus on Earth?
Answer: Rocks and sediments
Most of Earth's phosphorus is locked in rocks and marine sediments, making it unavailable until released by weathering over geological timescales.
An ecological pyramid of numbers can be inverted (wider at the top) when:
Answer: Parasites are counted and each host supports many parasites
A single large host organism can harbor thousands of parasites, so an inverted numbers pyramid occurs when parasites constitute the highest trophic level.
Which statement about ecosystem respiration is correct?
Answer: Ecosystem respiration includes both autotroph and heterotroph respiration
Ecosystem respiration is the sum of all aerobic respiration by producers, consumers, and decomposers, releasing CO₂ back into the atmosphere.
The ratio of Net Primary Productivity to Gross Primary Productivity (NPP/GPP) tends to be lowest in which environment?
Answer: Warm tropical ecosystems
In warm tropical ecosystems, high temperatures accelerate plant respiration rates, consuming a larger fraction of GPP, resulting in a lower NPP/GPP ratio.