Ideal Cell Size Lab | Biology with Ms Riley

Summary

In this lab, students explore the concept of ideal cell size by using agar cubes and vinegar to simulate diffusion in cells. The experiment involves three different cube sizes (1 cm, 2 cm, and 3 cm) and measures how far vinegar, representing nutrients, diffuses into the cubes. The cubes are observed for 15 minutes to see how their size affects the diffusion rate. Students calculate the diffusion distance, compare surface area to volume ratios, and analyze which cell size allows for the most effective nutrient absorption, reinforcing the importance of cell size in biological functions.

Takeaways

• 😀 The lab demonstrates the concept of ideal cell size using agar cubes as models of cells.
• 😀 Vinegar is used as a substance to simulate the diffusion process into the agar cubes.
• 😀 The agar cubes are colored pink due to phenolphthalein, which changes color when exposed to an acid.
• 😀 The lab uses cubes of three different sizes: 1 cm, 2 cm, and 3 cm, to test how diffusion occurs at different cell sizes.
• 😀 Pre-lab questions involve calculations to help understand the concepts before starting the procedure.
• 😀 The procedure involves placing the agar cubes in vinegar and timing the diffusion process for 15 minutes.
• 😀 After the diffusion period, the cubes are cut in half to observe how far the vinegar has diffused into each cube.
• 😀 The diffusion is measured by checking how much of the cube has turned clear (i.e., vinegar has diffused).
• 😀 Diffusion distance is measured on both sides of the cube to get the total distance the vinegar has penetrated.
• 😀 The lab emphasizes that smaller cells (cubes) are more efficient at absorbing nutrients due to their higher surface area to volume ratio.
• 😀 Students are asked to calculate the surface area to volume ratio and analyze how this affects the rate of diffusion and nutrient absorption in cells.

Q & A

What is the purpose of the Ideal Cell Size lab?

The purpose of the lab is to explore how the size of cells affects their ability to diffuse substances efficiently, using agar cubes soaked in vinegar to simulate diffusion in cells.

Why is phenolphthalein used in the agar cubes?

Phenolphthalein is used as an indicator that changes color from pink to clear in the presence of an acid, such as vinegar. This helps visualize how far the vinegar has diffused into the agar cubes.

Why is vinegar used in this experiment instead of other acids?

Vinegar is used because it is a safe and easy-to-find acid that can simulate the diffusion process in cells without being dangerous.

How are the diffusion rates of different cell sizes measured in the lab?

The diffusion rates are measured by cutting the agar cubes in half and measuring how far the vinegar has diffused into the cubes from the edges. The distance is measured on both sides of the cube to calculate the total diffusion.

What sizes of cubes are used in the experiment, and why are they chosen?

Three different sizes of agar cubes are used: 1 cm³, 2 cm³, and 3 cm³. These sizes are chosen to investigate how the size of the cell (cube) affects the rate of diffusion.

What is the role of the surface area-to-volume ratio in the experiment?

The surface area-to-volume ratio plays a crucial role in determining how efficiently a cell can diffuse nutrients. Smaller cells have a higher surface area-to-volume ratio, allowing for more efficient diffusion.

How does the diffusion process relate to real-life cells?

In real-life cells, nutrients and waste diffuse through the cell membrane. The rate of diffusion is affected by the cell’s size, and cells need to maintain an optimal size to maximize nutrient intake and waste removal.

What is the expected outcome when comparing the diffusion rates in the different-sized cubes?

The expected outcome is that the smaller cubes (with a higher surface area-to-volume ratio) will have more efficient diffusion, with a larger percentage of the cell being exposed to the vinegar compared to the larger cubes.

What mathematical calculations are involved in this experiment?

Students need to calculate the surface area-to-volume ratio for each cube and analyze the diffusion distances to determine which cube size would be optimal for diffusion in a biological context.

How does the size of the cube affect how much of it gets diffused?

Larger cubes will have less diffusion relative to their size because they have a smaller surface area-to-volume ratio. The vinegar can only diffuse so far, and larger cubes have more volume that is harder to reach with the diffusing substance.