Question

gummy bear lab
purpose: to investigate the movement of water by measuring the change in size of a gummy bear.
background: gummy bears are made of gelatin and sugar. diffusion is the movement of materials from an area of high concentration to an area of low concentration. osmosis is the diffusion of water. we will be using gummy bears to model osmosis and diffusion

prelab question:
a student places a piece of fresh potato (which contains living plant cells) into a highly salty solution and leaves it for an hour. when they check it later, the potato feels soft and flexible instead of firm.

question:
using your understanding of osmosis, explain what happened to the plant cells in the potato and why. be sure to describe the direction of water movement and how this affected the cells.

student name: _____________________________ id:_______________

respond with r.a.c.e.	short constructed response (scr)	checklist

| race
restate the question
answer the question
cite text evidence
explain what it means | _________________________
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_________________________ | ☐ did i use complete sentences?
☐ did i answer the question?
☐ did i use the text evidence?
☐ does my evidence back up my answer?
☐ is my response and evidence based on the text?
☐ does it have less than 450 characters? |

Explanation:

1. Restate the Question: We need to explain what happened to the plant cells in the potato when placed in a highly salty solution and why, including water movement direction and cell effects.
2. Answer the Question: The plant cells in the potato lost water, causing them to become plasmolyzed (soft and flexible).
3. Cite Text Evidence: From the background, osmosis is the diffusion of water from high to low concentration. The potato is in a highly salty (high solute, low water) solution, while the plant cells have lower solute (higher water) concentration.
4. Explain What It Means: Due to osmosis, water moved out of the plant cells (from the cell's higher water concentration to the solution's lower water concentration). As water left the vacuoles and cytoplasm, the cells lost turgor pressure, and the cell membrane pulled away from the cell wall, making the potato soft and flexible.

Answer:

To explain what happened to the plant cells in the potato:

• Restate: We explain the change in potato plant cells in a salty solution, including water movement and cell effects.
• Answer: The plant cells in the potato lost water, becoming soft and flexible.
• Evidence: Osmosis is water diffusion from high to low concentration (from background). The salty solution has high solute (low water), and plant cells have low solute (high water).
• Explanation: By osmosis, water moved out of the plant cells (from cell to solution, as solution has lower water concentration). This water loss reduced turgor pressure; the cell membrane shrank from the cell wall (plasmolysis), making the potato soft.