# Osmosis Investigation - effect of different strength of glucose solution on potato and apple strips.

Biology Lab Report

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Title: Transport across membrane

Aim: To investigate the osmosis in apple and potato tissue when immersed in different concentrations of glucose solution.

Research question: What is the effect in length of the potato and apple strips when submerged in glucose solution with difference concentration that is 0.2M, 0.3M, 0.4M, 0.5M and 1.0M for 120 minutes?

Hypothesis: As the concentration of the glucose solution gets higher, the differences in length of the strips get bigger.

Variables:

Independent variable: Concentrations of glucose solution.

Dependent variable: Different in length of the strips of apple and potato.

Constant variable:

1. Initial length of the apple and the potato strips which is 4.5 cm and their diameter 0.4 cm. The diameters are fixed by using exactly the same size cork borer while the length of the strips which is 4.5 cm measured using a 15 cm ruler.
2. Time taken for the apple and potato strips to be immersed in their respective glucose solution that is fixed to 120 minutes. The initial time of the strips started to immerse in the glucose solution is taken and they are taken out from the glucose solution after 120 minutes with uncertainties one minute.
3. Volume of the glucose solution which is fixed to 20 ml. The volumes are kept constant at 20 cm3 by measuring them using a measuring cylinder at each trial.

Materials: 50cm3 of 1.0 mol dm-3 glucose solution, distilled water, potato tuber, apple and filter paper.

Apparatus: Boiling tube, cork borer, 15 cm ruler, razor blade, tile, 25.0 cm3 measuring cylinder, forceps, covered Petri dish, stop-watch, marking pen, labelling paper and a 50 ml beaker, 10 cm3 pipette.

Data collection and processing:

Quantitative data :

Table 1.1: Table shows the recorded data for the initial length of the apple strips, cm and the final length of the potato strips, cm.

Table 1.2: Table shows the recorded data for the initial length of the potato strips, cm and the final length of the potato strips, cm.

By using the data in the table 1.1 and 1.2 the difference in length of the apple and potato strips are calculated by using the formula below.

Difference of length of each apple/potato strips, cm:

Initial length of each apple/potato strips, cm – Final length of each apple/potato strips, cm

For example:

The following shows the calculation for the potato strips immersed in 0.2 M of glucose solution.

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