Plant fibres fact file

Question 1

what is the independent variable

Answer 1

temperature/sucrose solution

Question 2

how do you vary the independent variable

Answer 2

water baths (10-60 degrees)
different sucrose solutions

Question 3

what is the dependent variable

Answer 3

tensile strength

Question 4

how do you measure the dependent variable

Answer 4

force/cross sectional area
use weight going up in 100g each time until the fibre breaks

Question 5

what is the organism variable and how is it controlled

Answer 5

length of fibres - use a ruler to measure equal lengths
age - make sure the celery fibres are from the same celery plant

Question 6

what are the environmental variables and how are they controlled

Answer 6

temperature - use water baths at set temperatures
humidity

Question 7

what are the procedural variables and how are they controlled

Answer 7

acclimatisation time - use a timer to ensure each celery fibre has been in the water bath for the same time (e.g. 10 minutes)

Question 8

what repeats should be carried out and how many

Answer 8

5 repeats of each water bath temperature and calculate the mean

Question 9

how is the investigation made safe

Answer 9

wearing goggles and a lab coat
placing carpet on the floor to take the force of the masses when they fall