Osmosis In Potato Required Practical - GCSE Biology | kayscience.com

Summary

This video demonstrates an experiment to determine the sugar concentration in a potato by using varying concentrations of sugar solutions. The process involves preparing potato cylinders, controlling key variables like species, age, and surface area, and measuring the initial and final mass after immersion in the solutions. The percentage change in mass is calculated and plotted against sugar concentration, with the graph showing an inverse relationship. The point where the line crosses the x-axis reveals the sugar concentration inside the potato, estimated at approximately 0.6 moles.

Takeaways

• 😀 Ensure the potato species and age are consistent for reliable results.
• 😀 Use a potato borer to extract cylinders of the same size and shape.
• 😀 Control the volume, temperature, and time of the sugar solution to maintain consistency.
• 😀 The potato cylinders should be weighed before and after submerging them in the sugar solutions.
• 😀 Always remove excess water from the cylinders using tissue paper to avoid inaccurate measurements.
• 😀 Calculate the percentage change in mass using the formula: (Final Mass - Initial Mass) / Initial Mass × 100.
• 😀 Plot the results on a graph, with percentage change in mass on the y-axis and sugar concentration on the x-axis.
• 😀 The point where the graph intersects the x-axis represents the concentration of sugar inside the potato.
• 😀 Osmosis causes the potato cylinders to either absorb or lose water based on the sugar concentration in the solution.
• 😀 The experiment demonstrates the concept of osmosis and how it affects the movement of water across plant cells.

Q & A

Why is it important to control the species of potato in the experiment?

The species of potato must be controlled because different species may have different sugar concentrations, affecting the results. Consistency in the species ensures that any changes in mass are due to the sugar concentration, not other variables.

What are the control variables in the experiment, and why are they necessary?

The control variables include the species of potato, the age of the potato, the surface area, and the volume of the potato cylinders. These are necessary to ensure the experiment's reliability and comparability, minimizing the effects of external factors on the results.

What happens if the potato cylinders are not the same length?

If the potato cylinders are not the same length, the surface area and volume of each cylinder would vary, leading to inconsistent results. Therefore, it is crucial to ensure that the cylinders are cut to the same length.

Why must you control the temperature of the sugar solutions?

The temperature of the sugar solutions must be controlled because temperature can affect the rate of osmosis, which in turn influences the mass change of the potato cylinders. Ensuring a constant temperature makes the results more reliable.

What role does dabbing the potato cylinders with tissue paper serve?

Dabbing the potato cylinders with tissue paper removes excess water from the surface. If this step is skipped, the extra water could affect the final mass measurement, leading to inaccurate results.

Why is it important to measure the initial mass of the potato cylinders?

Measuring the initial mass of the potato cylinders allows you to calculate the percentage change in mass after the experiment. This serves as a baseline for comparing how much mass has been gained or lost due to osmosis in different sugar concentrations.

What does a negative percentage change in mass indicate?

A negative percentage change in mass indicates that the potato cylinders lost mass, meaning water was likely drawn out of the potatoes due to osmosis in a higher sugar concentration solution.

How do you calculate the percentage change in mass of the potato cylinders?

The percentage change in mass is calculated using the formula: (Final mass - Initial mass) / Initial mass * 100. This allows you to compare the change in mass relative to the initial mass.

What does the point where the line intersects the x-axis represent on the graph?

The point where the line intersects the x-axis represents the concentration of sugar inside the potato, which is the point where the percentage change in mass is zero. This indicates the concentration at which the osmotic pressure inside the potato and the external sugar solution are balanced.

What is the purpose of plotting the percentage change in mass against sugar concentration?

Plotting the percentage change in mass against sugar concentration helps visualize the relationship between the two variables. Typically, you would see an inversely proportional relationship, indicating how the concentration of sugar influences the osmosis process in the potato.