the foodweb shows the flow of energy through a coastal marine ecosystem. assuming the phytoplankton has 100,000 joules of chemical energy, what can you infer about the amount of energy available to the other trophic levels? choose all that apply. a herbivores would have 10,000 j of energy available. b secondary consumers would have 1000 j of energy available. c the microorganisms have 6,000 j of energy available. d secondary consumers have 20% of the energy of the producers available. e the tertiary consumers have 1% of the energy from the phytoplankton available.

Question

Accepted Answer

# Brief Explanations:
1. **Rule of Energy Transfer in Food Chains**: In a food chain, energy is transferred from one trophic level to the next with about 10% of the energy being passed on (the 10% rule). Producers (phytoplankton here) are at the first trophic level. Primary consumers (herbivores) eat producers, secondary consumers eat primary consumers, and tertiary consumers eat secondary consumers. Decomposers break down all levels and receive energy from all, but the 10% rule applies to the main trophic levels (producer → primary → secondary → tertiary).

2. **Analyzing Each Option**:
   - **Option A**: Herbivores are primary consumers. If producers (phytoplankton) have 100,000 J, primary consumers should get ~10% (10,000 J). This matches the 10% rule.
   - **Option B**: Secondary consumers eat primary consumers. Primary consumers have ~10,000 J, so secondary consumers should get ~10% of that (1,000 J). This matches the 10% rule (10% of 10,000 is 1,000).
   - **Option C**: Decomposers receive energy from all trophic levels (producers, primary, secondary, tertiary), not just 10% of producers. Their energy isn’t limited to 10% of producers’ energy (which would be 10,000 J, not 6,000 J anyway). So this is incorrect.
   - **Option D**: Secondary consumers get ~10% of primary consumers’ energy. Primary consumers have ~10% of producers’ energy. So secondary consumers have ~10% of 10% = 1% of producers’ energy? Wait, no—wait, the option says “secondary consumers have 20% of the energy of the primary consumers”. The 10% rule is an average; sometimes it can be 5 - 20%, so 20% is possible (though 10% is typical). But let's check the math: If primary consumers have 10,000 J, 20% of that is 2,000 J. But the 10% rule is a general guideline—some ecosystems might have slightly more efficient transfer. However, let's check other options first. Wait, no—wait, the 10% rule is about the amount passed to the next trophic level (i.e., secondary consumers get ~10% of primary consumers’ energy, so if primary has 10,000 J, secondary has ~1,000 J). But the option says “secondary consumers have 20% of the energy of the primary consumers”—so 20% of 10,000 is 2,000 J. Is that possible? The 10% rule is an average; actual transfer can vary (5 - 20%), so 20% is within the possible range? Wait, no—wait, the key is the question is about a “coastal Maine ecosystem” and the 10% rule is a general rule, but maybe the question is using the 10% rule strictly? Wait, no—let's re - evaluate. Wait, the 10% rule is the amount of energy available to the next trophic level (i.e., the energy that is assimilated and available for growth/reproduction, not the total energy consumed). So primary consumers get ~10% of producers’ energy, secondary get ~10% of primary’s, etc. So secondary consumers should have ~10% of primary’s energy (1,000 J if primary has 10,000 J). But the option says 20%—so is that wrong? Wait, maybe I misread. Wait, the option says “secondary consumers have 20% of the energy of the primary consumers”. Let's check the numbers: If primary has 10,000 J, 20% is 2,000 J. But according to the 10% rule, it's 1,000 J. But maybe the question is considering that the 10% is a rough estimate and 20% is possible? Wait, no—let's check the other options. Wait, option E: “Tertiary consumers have 1% of the energy from the phytoplankton available”. Tertiary consumers are three levels above producers: producer (100%), primary (10%), secondary (1%), tertiary (0.1%)? Wait, no—wait, producer → primary (10%), primary → secondary (10% of 10% = 1%), secondary → tertiary (10% of 1% = 0.1%). Wait, the option says “1% of the energy from the phytoplankton”—but tertiary should have 0.1%? Wait, no, maybe the option is considering tertiary as the third level (producer is level 1, primary level 2, secondary level 3, tertiary level 4). Wait, no—trophic levels: Level 1: Producer (phytoplankton), Level 2: Primary Consumer (herbivore), Level 3: Secondary Consumer, Level 4: Tertiary Consumer. So energy at Level 2: 10% of Level 1 (10,000 J), Level 3: 10% of Level 2 (1,000 J), Level 4: 10% of Level 3 (100 J). So tertiary consumers would have 0.1% of producer’s energy (100 J / 100,000 J = 0.1%). But option E says “1% of the energy from the phytoplankton”—that would be 1,000 J, which is secondary consumers’ energy. So E is incorrect. Wait, but let's go back. Wait, the question is about a coastal Maine ecosystem food web (so multiple food chains, but the 10% rule still applies generally). Let's re - check each option:

- A: Herbivores (primary) → 10% of 100,000 = 10,000 J. Correct.
   - B: Secondary consumers → 10% of primary’s energy (10,000 J) = 1,000 J. Correct.
   - C: Decomposers get energy from all trophic levels, not just 10% of producers. And 6,000 J doesn't follow the 10% rule. Incorrect.
   - D: Secondary consumers have 20% of primary consumers’ energy. If primary has 10,000 J, 20% is 2,000 J. But the 10% rule is an average—sometimes transfer efficiency can be higher (up to 20% in some cases, especially with more efficient consumers or less energy lost). So is this possible? Wait, the 10% rule is a general rule, but actual transfer can vary between 5 - 20%. So if the primary consumers have 10,000 J, secondary could have 20% (2,000 J) if the transfer efficiency is 20%. But wait, in the standard 10% rule, it's 10%, but the option says “have 20% of the energy of the primary consumers”—so if primary has 10,000 J, secondary has 2,000 J. But according to the 10% rule, it's 1,000 J. But maybe the question is considering that the 10% is a minimum, and 20% is possible? Wait, no—let's check the original question again. The question says “Choose ALL that apply”. Let's re - analyze:

- The 10% rule: energy available to next trophic level is ~10% of the previous. So:
     - Producer (100,000 J) → Primary (10%: 10,000 J) → Secondary (10% of 10,000: 1,000 J) → Tertiary (10% of 1,000: 100 J).
   - Option A: Herbivores (primary) → 10,000 J. Correct.
   - Option B: Secondary consumers → 1,000 J. Correct.
   - Option D: “Secondary consumers have 20% of the energy of the primary consumers”. If primary has 10,000 J, 20% is 2,000 J. But according to the 10% rule, it's 1,000 J. But maybe the question is using a different transfer rate? Wait, no—maybe I made a mistake. Wait, the option says “secondary consumers have 20% of the energy of the primary consumers”. The primary consumers have 10,000 J (10% of producer). 20% of 10,000 is 2,000 J. But the 10% rule is about the energy available to the next trophic level (i.e., the energy that is not lost as heat, waste, etc.). So maybe in some cases, the transfer efficiency is higher? But the standard rule is 10%. However, the question is a multiple - choice, and we have to choose all that apply. Wait, maybe D is correct? Wait, no—let's check the other options. Option E: “Tertiary consumers have 1% of the energy from the phytoplankton available”. 1% of 100,000 is 1,000 J, which is secondary consumers’ energy. So E is incorrect. Option C: Decomposers—they don't follow the 10% rule from producers, so C is incorrect. So the correct options should be A, B, and maybe D? Wait, no—wait, let's check the 10% rule again. The 10% rule is the amount of energy that is transferred to the next trophic level (i.e., the energy that is used for growth and reproduction, not the total energy consumed). So primary consumers eat producers, but only about 10% of the energy from the producers is converted into the primary consumer’s biomass (available for the next trophic level). Similarly, secondary consumers get about 10% of the primary consumer’s biomass energy. So:

- Producer (phytoplankton): 100,000 J (biomass energy).
   - Primary consumers (herbivores): 10% of 100,000 = 10,000 J (biomass energy). So A is correct.
   - Secondary consumers: 10% of 10,000 = 1,000 J (biomass energy). So B is correct.
   - Tertiary consumers: 10% of 1,000 = 100 J (biomass energy), which is 0.1% of producer’s energy. So E is incorrect (says 1%, which is 1,000 J, secondary’s energy).
   - Decomposers: They break down all organisms, so their energy comes from all trophic levels, not just 10% of producers. So C is incorrect.
   - Secondary consumers having 20% of primary’s energy: If primary has 10,000 J, 20% is 2,000 J. But according to the 10% rule, it should be 1,000 J. But maybe the question is considering that the 10% is a rough estimate and 20% is possible? Wait, no—maybe I misread the option. Wait, the option says “secondary consumers have 20% of the energy of the primary consumers”. The primary consumers’ energy is 10,000 J (from producer). 20% of 10,000 is 2,000 J. But the 10% rule is about the energy available to the next trophic level, so secondary consumers should have ~10% of primary’s energy. So D is incorrect? But then only A and B? Wait, the original question’s options: Let me re - read the options:

- A: Herbivores would have 10,000 J of energy available. (Correct, 10% of 100,000)
   - B: Secondary consumers would have 1000 J of energy available. (Correct, 10% of 10,000)
   - C: The decomposers have 6,000 J of energy available. (Incorrect, decomposers get energy from all levels, not 10% of producer)
   - D: Secondary consumers have 20% of the energy of the primary consumers. (If primary has 10,000 J, 20% is 2,000 J. But 10% rule says 1,000 J. But maybe the question is using a different transfer rate? Or maybe “energy of the primary consumers” refers to the energy they consume, not their biomass energy? If primary consumers consume 100,000 J (but only 10,000 J is converted to biomass), then their consumed energy is 100,000 J, and secondary consumers might get 20% of that? But that's not how the 10% rule works. The 10% rule is about biomass energy (energy available for the next trophic level), not consumed energy. So D is incorrect.
   - E: Tertiary consumers have 1% of the energy from the phytoplankton available. 1% of 100,000 is 1,000 J, which is secondary’s energy. So E is incorrect.

So the correct options are A and B. Wait, but maybe the question considers that secondary consumers can have 20%? No, the 10% rule is a standard ecological principle. So A and B are correct.

# Answer:
A. Herbivores would have 10,000 J of energy available.
B. Secondary consumers would have 1000 J of energy available.

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Answer: