Cell Size and Diffusion: An Agar Experiment in Action

The video tutorial demonstrates a lab experiment to understand why cells are small. It involves using agar cubes with phenolphthalein and sodium hydroxide, which are placed in dilute hydrochloric acid. The experiment shows how diffusion occurs more rapidly in smaller cubes, illustrating the efficiency of nutrient diffusion in small cells. Observations are made at different time intervals, and the results highlight the advantages of smaller cell sizes in terms of diffusion rates.

What is the purpose of using phenolphthalein in the agar cubes?

• To make the cubes more solid

• To increase the size of the cubes

• To serve as a pH indicator

• To act as a nutrient source

What are the three sizes of agar cubes used in the experiment?

• 5 cm, 3 cm, 1 cm

• 4 cm, 3 cm, 2 cm

• 2.5 cm, 1.5 cm, 1 cm

• 3 cm, 2 cm, 1 cm

What is the role of dilute hydrochloric acid in the experiment?

• To increase the temperature of the solution

• To change the color of the cubes

• To facilitate diffusion through the cubes

• To dissolve the agar cubes

How does the diffusion rate compare between the smaller and larger cubes?

• Diffusion is faster in smaller cubes

• Diffusion is faster in larger cubes

• Diffusion does not occur in the cubes

• Diffusion rate is the same for all cubes

What observation is made about the smaller cube after two minutes?

• It remains completely colored

• It has not changed at all

• It is completely colorless

• Only a small part is still colored

Why are smaller cells more efficient in terms of diffusion?

• They have a larger surface area

• They have a smaller surface area

• They require more energy for diffusion

• Diffusion occurs more rapidly in smaller cells

What is the state of the medium cube after six minutes in the acid solution?

• Completely diffused

• Halfway diffused

• Not diffused at all

• Three-quarters diffused

What is the significance of cutting the cubes open at the end of the experiment?

• To measure the weight of the cubes

• To observe the internal diffusion

• To change the color of the cubes

• To increase the diffusion rate

What does the clear agar indicate in terms of pH?

• Lower pH

• Higher pH

• Neutral pH

• No change in pH

What conclusion can be drawn about cell size from this experiment?

• Larger cells are more efficient

• Smaller cells are more efficient

• Cell size does not affect efficiency

• Efficiency is unrelated to diffusion