Osmosis Worksheet: Animal Cells in Different Concentrations

This worksheet is about osmosis — the movement of water across a semipermeable membrane from an area of lower solute concentration to an area of higher solute concentration. The goal is to determine:

1. Direction of water movement (using arrows),
2. Missing percentages (water or solute),
3. Type of solution: isotonic, hypertonic, or hypotonic.

Let’s go through each beaker and explain the reasoning step by step.

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🔹 Osmosis Rules Recap:

- Water moves from low solute → high solute concentration.
- Hypertonic solution: Higher solute concentration outside → water leaves cell → cell shrinks.
- Hypotonic solution: Lower solute concentration outside → water enters cell → cell swells.
- Isotonic solution: Equal solute concentrations → no net movement.

> Note: In animal cells, if the solution is too hypotonic, the cell may burst (lyse). If too hypertonic, it shrivels (crenates).

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Now let's analyze each diagram:

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🟦 Top Row

#### 1. Cell: 90% H₂O, 10% solute
Beaker: 85% H₂O, 15% solute

- Solute in cell: 10%
- Solute in beaker: 15% → higher outside
- Water moves out of the cell → arrow ↓
- Solution is hypertonic → labeled "HYPER"

✔ Correct

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#### 2. Cell: 40% H₂O, 60% solute
Beaker: 90% H₂O, 10% solute

- Cell has 60% solute, beaker has 10% solute → much higher inside
- Water moves into cell → arrow ↑
- Beaker is hypotonic → labeled "HYPO"

✔ Correct

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#### 3. Cell: 75% H₂O, 25% solute
Beaker: 80% H₂O, 20% solute

- Cell: 25% solute
- Beaker: 20% solute → lower outside
- So, water moves into cell → arrow ↑
- Beaker is hypotonic → labeled "HYPO"

✔ Correct

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🟨 Middle Row

#### 4. Cell: 45% H₂O, 55% solute
Beaker: 75% H₂O, 25% solute

- Cell: 55% solute
- Beaker: 25% solute → lower outside
- Water moves into cell → arrow ↑
- Beaker is hypotonic → labeled "HYPO"

✔ Correct

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#### 5. Cell: 90% H₂O, 10% solute
Beaker: 63% H₂O, 37% solute

- Cell: 10% solute
- Beaker: 37% solute → higher outside
- Water moves out → arrow ↓
- Beaker is hypertonic → labeled "HYPER"

✔ Correct

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#### 6. Cell: 50% H₂O, 50% solute
Beaker: 50% H₂O, 50% solute

- Equal concentrations → no net movement
- Arrow is ↔ (or none), labeled "ISO" (isotonic)

✔ Correct

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🟩 Bottom Row

#### 7. Cell: 90% H₂O, 10% solute
Beaker: 90% H₂O, 10% solute

- Identical → isotonic
- No net movement → double-headed arrow or no arrow
- Labeled "ISO"

✔ Correct

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#### 8. Cell: 82% H₂O, 18% solute
Beaker: 25% H₂O, 75% solute

- Cell: 18% solute
- Beaker: 75% solute → much higher outside
- Water moves out → arrow ↓
- Beaker is hypertonic → labeled "HYPER"

✔ Correct

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#### 9. Cell: 90% H₂O, 10% solute
Beaker: 80% H₂O, 20% solute

- Cell: 10% solute
- Beaker: 20% solute → higher outside
- Water moves out → arrow ↓
- Beaker is hypertonic → labeled "HYPER"

✔ Correct

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✔ Summary of All Answers:

| Diagram | Water Movement | Solution Type |
|--------|----------------|---------------|
| 1 | ↓ | Hypertonic |
| 2 | ↑ | Hypotonic |
| 3 | ↑ | Hypotonic |
| 4 | ↑ | Hypotonic |
| 5 | ↓ | Hypertonic |
| 6 | ↔ (equal) | Isotonic |
| 7 | ↔ (equal) | Isotonic |
| 8 | ↓ | Hypertonic |
| 9 | ↓ | Hypertonic |

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💡 Key Concept Reminder:

- Water follows solute concentration.
- Always compare solute concentrations inside vs. outside.
- Use percentages consistently — if one side says 90% H₂O, then solute = 10%, etc.

All answers on the key are correct based on osmosis principles.

✔ Final Answer: The worksheet has been correctly completed as shown.