The total surface area to volume ratio and the diffusion rate over large distances are limiting factors to cellular activities in multicellular organisms.
Based on the above information, design a laboratory experiment to study the relationship between the total surface area to volume ratio and how it affects the rate of diffusion. Use the suitable plant tissue to design your experiment.
The planning of your experiment must include the following aspects :
Problem statement
Aim of investigation
Hypothesis
Variables
List of apparatus and materials
Technique used
Experimental procedure or method
Presentation of data
Conclusion [17 marks]
Suggested Answer:
Aim:To study the relationship between the total surface area to volume ratio and its effect on the rate of diffusion.
Problem Statement: How does the total surface area to volume ratio affect the the rate of diffusion ?
Hypothesis:The bigger the size of an object, the lower the total surface area to volume ratio and the lower the rate of diffusion.
Variables:
Manipulated variable – size of potato cube
Responding variable – percentage of stained area
Fixed variable- coloured solution, time
Apparatus and Materials:
Potatoes, coloured solution, Beakers, white tile, ruler, knife
TECHNIQUE : Observe, estimate and record the area of potato being stained using a graph paper .
Procedure:
Sample answer:
1. Use a knife to cut a potato cube of sides 1cm, 2cm and 3cm.
2. Calculate the total surface area and volume of the cube
3. Immerse all the cubes in a beaker containing coloured solution
for 30 minutes. Ensure all cubes are immersed in the coloured solution at the same time
4. Remove all the cubes after 30 minutes.
5. Cut each cube into two halves.
6. Observe the area stained for each cube.
7. Estimate the percentage of area stained using a graph paper and record the results in a table.
Conclusion : Rewrite hypothesis sentence
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