Worksheet designed to teach energy flow in ecosystems, featuring food chains and energy pyramids for calculating energy at each trophic level.

Let's solve each part of this problem step by step, focusing on energy transfer in trophic levels and completing the energy pyramids.

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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% is lost as heat due to metabolic processes (like respiration, movement, digestion), or it is used for life functions and not stored in biomass. Some energy may also be lost through waste (feces, urine) or remains that are not consumed by the next level.

> 🔍 *This reflects the 10% Rule in ecology: only about 10% of energy is transferred from one trophic level to the next.*

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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 available at the first level, then:
> - Second level = 1,000 × 0.10 = 100 kcal
> - Third level = 100 × 0.10 = 10 kcal
> - Fourth level = 10 × 0.10 = 1 kcal

So: Multiply the previous level’s energy by 0.10 (or divide by 10).

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Now let's complete the pyramids:

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Question 6: Acorn → Squirrel → Crow → Coyote

Given:
- 1,000 kcal at 1st level (Acorn)
- 100 kcal at 2nd level (Squirrel)
- 10 kcal at 3rd level (Crow)
- Find energy for tertiary consumer (Coyote) → 4th level

Using the 10% rule:
- 10 kcal (Crow) × 0.10 = 1 kcal for Coyote

#### ✔ Fill in pyramid (from bottom to top):

| Level | Organism | Energy (kcal) |
|-------|------------|---------------|
| 1st | Acorn | 1,000 |
| 2nd | Squirrel | 100 |
| 3rd | Crow | 10 |
| 4th | Coyote | 1 |

> 📌 So, 1 kcal is available for the tertiary consumer.

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Question 7: Phytoplankton → Shrimp → Snapper → Shark

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

Use 10% rule to calculate:

- 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)

#### ✔ Fill in pyramid:

| Level | Organism | Energy (kcal) |
|-------|--------------|---------------|
| 1st | Phytoplankton | 2,500 |
| 2nd | Shrimp | 250 |
| 3rd | Snapper | 25 |
| 4th | Shark | 2.5 |

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Question 8: Use food chain from #3 and complete the energy pyramid

But wait — #3 is missing from your image. Since you mentioned "use the food chain you created in #3", but we don’t have that information, I’ll assume a typical 4-level food chain (since #6 and #7 were 4-levels), and use a common example like:

> Grass → Rabbit → Fox → Eagle

But since the question says “use the food chain you created in #3,” and we can't see it, I will assume a standard 4-level food chain for demonstration purposes. Let’s suppose:

👉 Grass → Mouse → Snake → Hawk

We'll assign starting energy at the base. Typically, such problems start with a large number at the producer level.

Let’s say:
- 10,000 kcal at the 1st trophic level (Grass)

Then:

- 2nd level (Mouse): 10,000 × 0.10 = 1,000 kcal
- 3rd level (Snake): 1,000 × 0.10 = 100 kcal
- 4th level (Hawk): 100 × 0.10 = 10 kcal

#### ✔ Fill in pyramid:

| Level | Organism | Energy (kcal) |
|-------|------------|---------------|
| 1st | Grass | 10,000 |
| 2nd | Mouse | 1,000 |
| 3rd | Snake | 100 |
| 4th | Hawk | 10 |

> ⚠️ Note: If you had a different food chain in #3 (e.g., algae → fish → bird → owl), just substitute accordingly. But since we don’t have #3, this is a reasonable assumption based on typical textbook examples.

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✔ Final Answers Summary:

#### Question 4:
> The other 90% is lost as heat during metabolism, used for life processes, or lost as waste.

#### Question 5:
> Multiply the energy at the previous level by 0.10 (or divide by 10).

#### Question 6:
- Tertiary consumer (Coyote): 1 kcal
- Pyramid:
- Bottom: Acorn – 1,000 kcal
- Next: Squirrel – 100 kcal
- Next: Crow – 10 kcal
- Top: Coyote – 1 kcal

#### Question 7:
- 2nd level: 250 kcal
- 3rd level: 25 kcal
- 4th level: 2.5 kcal
- Pyramid:
- Bottom: Phytoplankton – 2,500 kcal
- Next: Shrimp – 250 kcal
- Next: Snapper – 25 kcal
- Top: Shark – 2.5 kcal

#### Question 8:
Assuming food chain: Grass → Mouse → Snake → Hawk
- 1st level: 10,000 kcal
- 2nd level: 1,000 kcal
- 3rd level: 100 kcal
- 4th level: 10 kcal

Pyramid:
- Bottom: Grass – 10,000 kcal
- Next: Mouse – 1,000 kcal
- Next: Snake – 100 kcal
- Top: Hawk – 10 kcal

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If you can provide the food chain from #3, I can adjust Question 8 accordingly!