Surface Area to Volume Ratio in Cells

Dr. Wifer explains the agar diffusion lab for AP Biology, focusing on why cells are small. The lab uses phenolphthalein and agar blocks to demonstrate diffusion. Students learn to calculate surface area and volume ratios, observing how smaller blocks diffuse faster. The video concludes with the efficiency of small cells in exchanging materials.

What is the main question the agar diffusion lab aims to answer?

• What is the role of DNA in cells?

• How do cells generate energy?

• How do cells divide?

• Why are cells so small?

What happens to phenolphthalein when a base is added?

• It turns blue

• It turns pink

• It turns green

• It remains clear

What is the purpose of cutting the agar block into smaller pieces?

• To make it dissolve faster

• To increase its weight

• To change its color

• To compare diffusion rates

How do you calculate the surface area of a cube?

• 6 x (Length x Width)

• Side x Side x Side

• Length x Width

• Length x Width x Height

Why is the surface area to volume ratio important for cells?

• It determines the cell's color

• It affects the cell's ability to exchange materials

• It controls the cell's energy production

• It influences the cell's genetic material

What was observed after 5 minutes of placing the agar blocks in vinegar?

• No change was observed

• The small blocks showed clear coloring

• The large block turned completely clear

• The vinegar changed color

How long did it take for the uncut block to become completely clear?

• 10 minutes

• 20 minutes

• 30 minutes

• 40 minutes

What is one reason cells are small?

• To decrease energy consumption

• To increase surface area to volume ratio

• To reduce genetic material

• To store more nutrients

What is one way cells can increase their surface area?

• By changing their color

• By dividing into smaller cells

• By increasing their volume

• By reducing their energy consumption

What was the main conclusion of the agar diffusion lab?

• Larger blocks diffuse faster

• Smaller blocks have a higher surface area to volume ratio

• Phenolphthalein is not a reliable indicator

• Vinegar does not affect diffusion