Osmosis worksheet with educational questions and diagrams illustrating water movement in cells, plant roots, and beverage effects on hydration.

Let's go through each question on the worksheet step by step, explaining the concepts and providing answers based on osmosis — the movement of water across a semi-permeable membrane from an area of lower solute concentration to an area of higher solute concentration.

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1. Why wouldn't bacteria be able to survive on salted fish? Explain using the concept of osmosis.

Answer:
Salted fish has a very high concentration of salt (solute) outside the bacterial cells. When bacteria come into contact with this salty environment, water inside the bacterial cells moves out through the cell membrane via osmosis because the external environment is hypertonic compared to the inside of the cell. This causes the bacteria to lose water, shrink (plasmolysis), and eventually die due to dehydration. The process disrupts their cellular functions and metabolism.

> ✔ Explanation: Osmosis leads to water leaving the bacterial cells → cell shrivels → death.

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2. The cells in the beakers shown below are permeable to water only. Indicate the tonicity of each solution AND indicate the direction of water movement.

We have three diagrams:

#### Beaker A:
- The cell appears swollen or bursting, and there’s a dissolved particle outside.
- The solution outside has fewer solutes than inside the cell.
- So, the outside solution is hypotonic to the cell.
- Water moves into the cell.

✔ Tonicity: Hypotonic
✔ Water Movement: Into the cell

#### Beaker B:
- The cell looks normal, not swollen or shriveled.
- The number of solute particles inside and outside appears equal.
- No net movement of water.

✔ Tonicity: Isotonic
✔ Water Movement: No net water movement

#### Beaker C:
- The cell appears shrunken (plasmolyzed).
- There are more solute particles outside than inside.
- Water moves out of the cell.

✔ Tonicity: Hypertonic
✔ Water Movement: Out of the cell

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3. The roots of a plant have cells that absorb water from the soil. There is a high concentration of minerals inside the root cells compared to the minerals in the soil.

#### a. Explain why water moves from the soil into the root hair cell.

Answer:
The root hair cells contain a higher concentration of dissolved minerals (solutes) than the surrounding soil. Because of this difference, the soil is hypotonic relative to the root cell, and the root cell is hypertonic relative to the soil. Water moves by osmosis from the area of lower solute concentration (soil) to the area of higher solute concentration (root cell).

> ✔ Explanation: Water follows the concentration gradient — moving from low solute to high solute concentration.

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#### b. Complete each sentence below.

1. The soil is hypotonic compared to the root cells.
2. The root cells are hypertonic compared to the soil.

> ✔ These terms describe the relative concentrations of solutes between the two environments.

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4. Soft drinks may contain various concentrations of solutes... Which of these drinks should be marketed as "thirst quenchers"? Explain your answer in terms of water concentration and water movement.

Answer:
Soft drinks with low solute concentration (like plain water or lightly sweetened drinks) should be marketed as "thirst quenchers" because they are hypotonic compared to body cells.

- When you drink a hypotonic beverage, water moves into your cells by osmosis, helping to rehydrate them.
- In contrast, drinks with high solute concentration (e.g., sugary sodas) are hypertonic and can cause water to move out of your cells into the drink, leading to dehydration and worsening thirst.

> ✔ Conclusion: Only soft drinks that are hypotonic (low solute) help hydrate the body and should be called “thirst quenchers.”

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✔ Final Answers Summary:

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1. Bacteria die on salted fish because the high salt concentration causes osmotic loss of water from bacterial cells (plasmolysis), leading to cell death.

2.
| Beaker | Tonicity | Direction of Water Movement |
|--------|--------------|-----------------------------|
| A | Hypotonic | Into the cell |
| B | Isotonic | No net movement |
| C | Hypertonic | Out of the cell |

3.a. Water moves from soil into root hair cells because the root cells have a higher solute concentration, so water moves by osmosis into the cell.

3.b.
1. The soil is hypotonic compared to the root cells.
2. The root cells are hypertonic compared to the soil.

4. Drinks with low solute concentration (hypotonic) should be marketed as "thirst quenchers" because they allow water to enter body cells, aiding hydration. High-solute drinks (hypertonic) draw water out of cells and worsen dehydration.

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