Worksheet on diffusion and osmosis with examples and diagrams for educational use.

Here is the solution to the Diffusion and Osmosis Worksheet, with explanations for each answer.

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Definitions Recap:

* Diffusion: The movement of molecules (solutes or gases) from an area of higher concentration to an area of lower concentration. It happens until equilibrium is reached. This can occur in air, water, or across membranes.
* Osmosis: A specific type of diffusion involving the movement of *water* molecules across a semi-permeable membrane from an area of lower solute concentration (higher water concentration) to an area of higher solute concentration (lower water concentration).

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Answers and Explanations (Questions 1-7):

1. The student sitting next to you just came from gym class and forgot to shower and you can tell.
* Answer: DIFFUSION
* Explanation: You are smelling the odor molecules (sweat, bacteria byproducts) that have moved through the air from the student (high concentration near them) to your nose (low concentration). This is the passive movement of molecules down their concentration gradient – diffusion.

2. After sitting in the bathtub for hours, your fingers start to look like prunes.
* Answer: OSMOSIS
* Explanation: The bathwater has a much lower concentration of solutes (like salts and proteins) than the fluid inside your skin cells. Water moves *into* your skin cells via osmosis, causing them to swell. The outer layer of skin wrinkles as it absorbs water and expands unevenly.

3. The girl sitting two rows ahead of you put on too much perfume this morning.
* Answer: DIFFUSION
* Explanation: Similar to question 1, the perfume molecules are moving through the air from the source (the girl, high concentration) to your nose (low concentration). This is diffusion of gas molecules.

4. One way to get rid of slugs in your garden is to sprinkle salt on them, so they shrivel up.
* Answer: OSMOSIS
* Explanation: Sprinkling salt creates a very high solute concentration outside the slug's body. The slug's body fluids have a lower solute concentration (higher water concentration). Water moves *out* of the slug's cells into the salty environment via osmosis, causing the slug to dehydrate and shrivel.

5. Yum! Something smells good. The neighbors are cooking on the grill!
* Answer: DIFFUSION
* Explanation: The smell molecules from the food are diffusing through the air from the grill (high concentration) to your location (low concentration).

6. Gargling with salt water when you have a sore throat causes your swollen throat cells to shrink and feel better.
* Answer: OSMOSIS
* Explanation: The salt water gargle has a higher solute concentration than the fluid inside your swollen throat cells. Water moves *out* of the cells into the salt water via osmosis, reducing the swelling and relieving pressure/pain.

7. Oxygen molecules move from the air sacs in the lungs across the cell membranes into the blood.
* Answer: DIFFUSION
* Explanation: Oxygen concentration is higher in the air sacs (alveoli) than in the blood capillaries surrounding them. Oxygen molecules passively diffuse across the thin cell membranes from the area of high concentration (lungs) to low concentration (blood). While this involves crossing membranes, it's the movement of the *solute* (oxygen gas), not water, so it's diffusion.

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Question 8: Indicating Direction of Diffusion

You need to draw arrows showing the direction molecules (○) will move across the cell membrane (□) to reach equilibrium (even distribution).

* A) Inside the box (cell), there are many molecules (○). Outside the box, there are fewer molecules. Molecules will diffuse *out* of the cell (from high concentration inside to low concentration outside).
* Draw arrows pointing OUT of the box.

* B) Inside the box (cell), there are very few molecules (○). Outside the box, there are many molecules. Molecules will diffuse *into* the cell (from high concentration outside to low concentration inside).
* Draw arrows pointing INTO the box.

*(Note: Since I cannot physically draw on the image, the instructions above describe exactly where to place the arrows.)*

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Summary of Answers:

1. DIFFUSION
2. OSMOSIS
3. DIFFUSION
4. OSMOSIS
5. DIFFUSION
6. OSMOSIS
7. DIFFUSION
8. A) Arrows point OUT of the box. B) Arrows point INTO the box.