Question

jordan wants to calculate the amount of energy the bird of prey in this energy pyramid obtains. if the grasses have 9,000 kilocalories (kcal) available, how much energy will the bird receive? question 2 / 5 a 0.9 kcal b 450 kcal c 4500 kcal d 90 kcal

Explanation:

Step1: Recall energy pyramid rule

In an energy pyramid, typically about 10% of energy is transferred between trophic levels. The grasses are producers (bottom level). Let's count the trophic levels to the bird: grasses → primary consumers → secondary consumers → tertiary consumers → bird? Wait, looking at the pyramid: grasses (level 1), then insects (level 2), then small fish (level 3), then big fish (level 4), then bird (level 5). Wait, no, maybe the levels are: grasses (producers, level 1), primary consumers (level 2), secondary (level 3), tertiary (level 4), quaternary (bird, level 5)? Wait, no, maybe the bird is 4th level? Wait, the pyramid has grasses at bottom, then insects, then small fish, then big fish, then bird. So from grasses (level 1) to bird (level 5)? Wait, no, maybe the number of trophic levels between grasses and bird: grasses (level 1), primary consumers (level 2), secondary (level 3), tertiary (bird, level 4)? Wait, let's check the 10% rule. Each level gets 10% of the previous. So grasses (9000 kcal) → level 2: \( 9000 \times 0.1 = 900 \) kcal. Level 3: \( 900 \times 0.1 = 90 \) kcal. Level 4: \( 90 \times 0.1 = 9 \) kcal? No, that doesn't match options. Wait, maybe the bird is 3 levels above? Wait, maybe the pyramid is: grasses (level 1), primary (level 2), secondary (level 3), bird (level 4). Wait, let's re-examine the image: grasses at bottom, then insects (level 2), then small fish (level 3), then big fish (level 4), then bird (level 5)? No, the options include 90 kcal. Wait, maybe the bird is 3 trophic levels above grasses: grasses (level 1) → level 2 (10%: 900), level 3 (10%: 90), level 4 (bird, 10%: 9)? No. Wait, maybe I miscounted. Wait, the energy pyramid's 10% rule: each trophic level (except producers) gets 10% of the energy from the level below. So if grasses are level 1 (producers, 9000 kcal), level 2 (primary consumers): \( 9000 \times 0.1 = 900 \) kcal. Level 3 (secondary consumers): \( 900 \times 0.1 = 90 \) kcal. Level 4 (tertiary consumers, bird?): \( 90 \times 0.1 = 9 \) kcal? No. Wait, the options have 90 kcal. Wait, maybe the bird is at level 3? Wait, maybe the pyramid is grasses (level 1), primary (level 2: 900), secondary (level 3: 90), and bird is level 3? No. Wait, maybe the question's pyramid has grasses, then herbivores, then small carnivores, then bird. So grasses (9000) → herbivores (900) → small carnivores (90) → bird (9). No. Wait, the options: D is 90 kcal. Wait, maybe the bird is two levels above? Grasses (9000) → level 2 (900) → level 3 (90) → bird (level 3? No). Wait, maybe the bird is at the third trophic level? Wait, maybe the pyramid is: grasses (level 1), primary consumers (level 2: 900), secondary consumers (bird, level 3: 900×0.1=90). Ah! That must be it. So grasses (level 1) → primary consumers (level 2: 9000×0.1=900) → secondary consumers (bird, level 3: 900×0.1=90). So the bird receives 90 kcal.

Step2: Calculate energy transfer

Using the 10% energy transfer rule (each trophic level gets 10% of the previous level's energy). Let's assume the bird is two trophic levels above the grasses (grasses → primary → bird). Wait, no, maybe three? Wait, no, the calculation:

Grasses: 9000 kcal (level 1)

Level 2 (primary consumers): \( 9000 \times 0.1 = 900 \) kcal

Level 3 (secondary consumers): \( 900 \times 0.1 = 90 \) kcal

If the bird is at level 3, then it gets 90 kcal, which is option D.

Answer:

D. 90 kcal