Diffusion and Osmosis Worksheet featuring questions, diagrams, and answers related to cellular transport processes.

Worksheet: Diffusion and Osmosis

#### 1. How are the molecules moving in the examples below? Write OSMOSIS or DIFFUSION.

- a. The student sitting next to you just came from gym class and forgot to shower and you can tell.
- Answer: DIFFUSION
- Explanation: The smell of sweat is a gas (odor molecules) diffusing through the air, spreading from an area of high concentration (near the student) to an area of low concentration (farther away).

- b. After sitting in the bathtub for hours, your fingers start to look like prunes.
- Answer: OSMOSIS
- Explanation: Water moves into the cells of your skin by osmosis because the water concentration outside the cells (in the bathtub) is higher than inside the cells.

- c. The girl sitting two rows ahead of you put on too much perfume this morning.
- Answer: DIFFUSION
- Explanation: Perfume is a gas that diffuses through the air, spreading from an area of high concentration (near the girl) to an area of low concentration (farther away).

- d. One way to get rid of slugs in your garden is to sprinkle salt on them, so they shrivel up.
- Answer: OSMOSIS
- Explanation: When salt is sprinkled on slugs, it creates a hypertonic environment outside the slug's cells. Water moves out of the cells by osmosis, causing the slugs to dehydrate and shrivel.

- e. Yum! Something smells good. The neighbors are cooking on the grill!
- Answer: DIFFUSION
- Explanation: The aroma of food is a gas that diffuses through the air, spreading from the source (the grill) to your nose.

- f. Gargling with salt water when you have a sore throat causes your swollen throat cells to shrink and feel better.
- Answer: OSMOSIS
- Explanation: Salt water is hypertonic compared to the fluid inside your throat cells. Water moves out of the cells by osmosis, reducing swelling.

- g. Oxygen molecules move from the air sacs in the lungs across the cell membranes into the blood.
- Answer: DIFFUSION
- Explanation: Oxygen diffuses from the air sacs (alveoli) in the lungs, where it is at a higher concentration, into the bloodstream, where it is at a lower concentration.

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#### 2. Use arrows to indicate the direction of diffusion in each case below:

- A)
- Answer: Arrows pointing downward.
- Explanation: The particles are more concentrated at the top of the box. Diffusion will cause them to spread downward to achieve equilibrium.

- B)
- Answer: Arrows pointing inward toward the box.
- Explanation: The particles are more concentrated outside the box. Diffusion will cause them to move into the box to achieve equilibrium.

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#### 3. For each of the situations below, use an arrow to indicate the net movement of sugar into or out of the cell. (Assume that the sugar molecules can pass through the cell membrane in each case.)

- Case 1: 1% sugar (inside cell), 5% sugar (outside cell)
- Answer: Arrow pointing upward (out of the cell).
- Explanation: Sugar will diffuse out of the cell because the concentration is higher outside the cell.

- Case 2: 3% sugar (inside cell), 1% sugar (outside cell)
- Answer: Arrow pointing downward (into the cell).
- Explanation: Sugar will diffuse into the cell because the concentration is higher inside the cell.

- Case 3: 1% sugar (inside cell), 1% sugar (outside cell)
- Answer: Arrow pointing both ways (no net movement).
- Explanation: Since the concentrations are equal, there will be no net movement of sugar.

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#### 4. Diffusion always causes particles to move from a region of ________ concentration to a region of ________ concentration.

- Answer: high → low
- Explanation: Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration until equilibrium is reached.

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#### 5. Does a cell use energy when molecules diffuse in or out of the cell? Why?

- Answer: No
- Explanation: Diffusion is a passive process that does not require energy. It occurs due to the random motion of particles and their tendency to move from areas of high concentration to areas of low concentration.

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Final Answer Summary:

1. Examples:
- a. Diffusion
- b. Osmosis
- c. Diffusion
- d. Osmosis
- e. Diffusion
- f. Osmosis
- g. Diffusion

2. Diffusion Directions:
- A: Downward
- B: Inward

3. Sugar Movement:
- Case 1: Out of the cell
- Case 2: Into the cell
- Case 3: No net movement

4. Concentration Gradient:
- High → Low

5. Energy Usage:
- No, because diffusion is passive.

Final Boxed Answers:
\[
\boxed{
\text{1. a. Diffusion, b. Osmosis, c. Diffusion, d. Osmosis, e. Diffusion, f. Osmosis, g. Diffusion}
}
\]
\[
\boxed{
\text{2. A: Downward, B: Inward}
}
\]
\[
\boxed{
\text{3. Case 1: Out, Case 2: In, Case 3: No net movement}
}
\]
\[
\boxed{
\text{4. High → Low}
}
\]
\[
\boxed{
\text{5. No, because diffusion is passive.}
}
\]