Question

1. the following diagram shows the carbon cycle. what does x represent in the diagram? (diagram description: co₂ is in the atmosphere → x → consumers eat producers → y → co₂ is in the atmosphere) a. carbon in dead plants and animals, because they decompose carbon in the air and animals use it in respiration b. carbon caught in the soil, because animals drink this carbon from runoff and use it for photosynthesis, releasing carbon dioxide into the air c. carbon in dead plants and animals, because they decompose carbon in the air and animals use it in photosynthesis d. carbon in living plants, because plants carry out photosynthesis, taking in carbon dioxide to make sugars that are eaten by animals 32. what happens to an ecosystem if producers disappear? a. more energy will be available for the tertiary consumers b. the starting energy would be lost for all the organisms c. the primary consumers would start to eat the secondary consumers d. sunlight would be absorbed by the primary consumers for energy production 33. too much phosphorous in waterways (lakes, rivers) can lead to ___. a. eutrophication b. diseases c. death of algae and emergent plants (plants that root in soil underwater but grow above the water) d. fossilization

Explanation:

Question 31

To determine what X represents in the carbon cycle diagram, we analyze the flow: \( \text{CO}_2 \) in the atmosphere → X → Consumers eat producers. Producers (living plants) perform photosynthesis, taking in \( \text{CO}_2 \) to make sugars (becoming food for consumers). Option A: Dead plants/animals decompose, but X comes before consumers eating producers, so not dead organisms. Option B: Soil carbon and animals doing photosynthesis (animals don’t do photosynthesis) is wrong. Option C: Animals doing photosynthesis is incorrect. Option D matches: Living plants (producers) do photosynthesis, take in \( \text{CO}_2 \), make sugars eaten by animals.

Producers (e.g., plants) capture energy (via photosynthesis) and start the food chain. If producers disappear: A. Tertiary consumers need energy from lower levels; no producers means less energy, not more. B. Producers are the energy source (start of food chain); no producers, all organisms lose the starting energy. C. Primary consumers eat producers, secondary eat primary; primary won’t eat secondary (different trophic levels, wrong diet). D. Primary consumers can’t absorb sunlight for energy (only producers do photosynthesis with sunlight). So B is correct.

Phosphorus in waterways: Eutrophication is excessive nutrient (like phosphorus) causing algal blooms, depleting oxygen. A. Eutrophication matches (excess P leads to rapid algae growth, eutrophication). B. Diseases: Not directly caused by excess P in water. C. Excess P causes algae blooms (not death of algae/emergent plants initially; blooms can later kill them, but the direct effect is eutrophication). D. Fossilization is long - term, not from excess P in waterways. So A is correct.

Answer:

D. Carbon in living plants, because plants carry out photosynthesis, taking in carbon dioxide to make sugars that are eaten by animals

Question 32