Biology worksheet guiding students through energy transfer calculations using the 10% rule across different food chains.

Let's solve each question step by step, based on the principles of energy transfer in ecological food chains.

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Question 4:

Only 10% of the energy available at each trophic level moves on to the next level. What happens to the other 90%?

✔ Answer:
The other 90% of the energy is lost as heat due to metabolic processes (like respiration, movement, digestion), and some is lost as waste (feces, urine). This follows the 10% Rule in ecology.

> 🔹 Energy is not recycled; it flows one-way through ecosystems.
> 🔹 Most energy is used for life functions or lost as heat.

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Question 5:

An easy way to calculate the amount of energy available at each level is to...

✔ Answer:
Multiply the energy at the previous level by 0.10 (or divide by 10).

> ✔ Example: If 1,000 kcal is at the first level, then second level = 1,000 × 0.10 = 100 kcal.

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Question 6: Acorn → Squirrel → Crow → Coyote

Given:
- 1st trophic level (Acorn): 1,000 kcal
- 2nd (Squirrel): 100 kcal
- 3rd (Crow): 10 kcal
- 4th (Coyote, tertiary consumer): ?

We apply the 10% rule:
Each level gets 10% of the previous level’s energy.

So:
- Tertiary consumer (Coyote) = 10 kcal × 0.10 = 1 kcal

Now fill in the pyramid from bottom to top:

```
[1 kcal] ← Coyote (4th)
[10 kcal] ← Crow (3rd)
[100 kcal] ← Squirrel (2nd)
[1,000 kcal] ← Acorn (1st)
```

✔ Answer for Q6:
- Tertiary consumer (Coyote): 1 kcal

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Question 7: Phytoplankton → Shrimp → Snapper → Shark

Given:
- 1st level (Phytoplankton): 2,500 kcal

Use the 10% rule:

- 2nd level (Shrimp) = 2,500 × 0.10 = 250 kcal
- 3rd level (Snapper) = 250 × 0.10 = 25 kcal
- 4th level (Shark) = 25 × 0.10 = 2.5 kcal ✔ (matches given)

Now fill in the pyramid:

```
[2.5 kcal] ← Shark (4th)
[25 kcal] ← Snapper (3rd)
[250 kcal] ← Shrimp (2nd)
[2,500 kcal] ← Phytoplankton (1st)
```

✔ Answers for Q7:
- 2nd trophic level: 250 kcal
- 3rd trophic level: 25 kcal

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Question 8: Use the food chain you created in #3 and complete the energy pyramid

⚠️ Problem: You mentioned “the food chain you created in #3”, but #3 is not shown in this image.

Since we don’t have the original food chain from #3, I’ll assume a typical 4-level food chain for demonstration purposes — let’s use:

👉 Grass → Rabbit → Fox → Hawk

Assume 10,000 kcal at the first level (producer, Grass).

Then:
- 1st level (Grass): 10,000 kcal
- 2nd (Rabbit): 10,000 × 0.10 = 1,000 kcal
- 3rd (Fox): 1,000 × 0.10 = 100 kcal
- 4th (Hawk): 100 × 0.10 = 10 kcal

Now fill in the pyramid:

```
[10 kcal] ← Hawk (4th)
[100 kcal] ← Fox (3rd)
[1,000 kcal] ← Rabbit (2nd)
[10,000 kcal] ← Grass (1st)
```

✔ So answers for Q8 would be:
- 1st trophic level: 10,000 kcal
- 2nd trophic level: 1,000 kcal
- 3rd trophic level: 100 kcal
- 4th trophic level: 10 kcal

> ⚠️ Note: These values depend on what was chosen in #3. If your #3 had a different food chain or starting energy, adjust accordingly. But since it's missing, this is a reasonable assumption.

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✔ Final Answers Summary:

#### Q4:
The other 90% is lost as heat through metabolism and waste.

#### Q5:
Multiply the energy at the previous level by 0.10 (or divide by 10).

#### Q6:
- Tertiary consumer (Coyote): 1 kcal
Pyramid:
```
[1 kcal]
[10 kcal]
[100 kcal]
[1,000 kcal]
```

#### Q7:
- 2nd level: 250 kcal
- 3rd level: 25 kcal
Pyramid:
```
[2.5 kcal]
[25 kcal]
[250 kcal]
[2,500 kcal]
```

#### Q8: *(Assuming Grass → Rabbit → Fox → Hawk, 10,000 kcal start)*
- 1st: 10,000 kcal
- 2nd: 1,000 kcal
- 3rd: 100 kcal
- 4th: 10 kcal
Pyramid:
```
[10 kcal]
[100 kcal]
[1,000 kcal]
[10,000 kcal]
```

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If you can provide the food chain from #3, I can update the answer for Q8 precisely. Otherwise, this is a standard example based on typical ecology problems.