Question

1. phytoplankton → shrimp → snapper → shark

250 kcal available for the 3rd trophic level.
fill in the organisms and energy amounts on the
pyramid to the right.

Explanation:

Step1: Identify Trophic Levels

The food chain is Phytoplankton (1st) → Shrimp (2nd) → Snapper (3rd) → Shark (4th). Energy at 3rd level (Snapper) is 250 kcal? Wait, no—wait, the problem says "250 kcal available for the 3rd trophic level"? Wait, no, let's re-express. In energy pyramids, only ~10% of energy is transferred between trophic levels (10% rule). So:

• 1st level (Phytoplankton): Let's find energy for each level. Wait, the 3rd level (Snapper) has 250 kcal? Wait, no—wait, the food chain is Phytoplankton (1st) → Shrimp (2nd) → Snapper (3rd) → Shark (4th). So energy transfer: 1st to 2nd: 10% of 1st, 2nd to 3rd: 10% of 2nd, 3rd to 4th: 10% of 3rd. Wait, but the problem says "250 kcal available for the 3rd trophic level". Wait, no—maybe the 2nd level (Shrimp) has 250 kcal? Wait, the text: "2. Phytoplankton → Shrimp → Snapper → Shark 250 kcal available for the 3rd trophic level." Wait, maybe typo: 250 kcal for 3rd (Snapper). Then:

Step2: Calculate Energy for Each Level

• 3rd level (Snapper): 250 kcal (given? Wait, no—wait, the 10% rule: energy at level \( n \) is \( 0.1 \times \) energy at level \( n-1 \). So if 3rd level (Snapper) has \( E_3 = 250 \) kcal, then:

• 2nd level (Shrimp): \( E_2 = \frac{E_3}{0.1} = \frac{250}{0.1} = 2500 \) kcal

• 1st level (Phytoplankton): \( E_1 = \frac{E_2}{0.1} = \frac{2500}{0.1} = 25000 \) kcal

• 4th level (Shark): \( E_4 = 0.1 \times E_3 = 0.1 \times 250 = 25 \) kcal

Wait, but the pyramid has four levels (Phytoplankton, Shrimp, Snapper, Shark). So the energy amounts from bottom (1st) to top (4th) would be 25000 kcal, 2500 kcal, 250 kcal, 25 kcal.

Wait, but the problem says "250 kcal available for the 3rd trophic level"—so 3rd level (Snapper) is 250 kcal. Then:

• 1st (Phytoplankton): \( 250 / 0.1 / 0.1 = 25000 \) kcal

• 2nd (Shrimp): \( 250 / 0.1 = 2500 \) kcal

• 3rd (Snapper): 250 kcal

• 4th (Shark): \( 250 \times 0.1 = 25 \) kcal

So the pyramid (from bottom, largest to top, smallest) would have:

Bottom (1st): 25000 kcal (Phytoplankton)

Next (2nd): 2500 kcal (Shrimp)

Next (3rd): 250 kcal (Snapper)

Top (4th): 25 kcal (Shark)

Answer:

From bottom (1st trophic level) to top (4th):

• Phytoplankton: 25000 kcal
• Shrimp: 2500 kcal
• Snapper: 250 kcal
• Shark: 25 kcal

(Assuming the 3rd trophic level (Snapper) has 250 kcal, applying the 10% energy transfer rule between trophic levels.)