Investigating Variation in Leaf Size

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Investigating Variation in Leaf Size

Aim:

How much variation will we observe between species in terms of leaf area?  How will this compare with variation within species (or between leaves of the same individual)?

Description:

The leaves of plants are adapted to maximize photosynthesis.  They are also adapted to water availability and humidity.  The size, shape and number of leaves on a given plant will reflect the conditions of its native habitat.

Method:

  • Firstly, form a group of two to three people
  • Then go outside into the garden area and collect a pair of four different types of leaves.  Try to collect a variation in leaf size.
  • After that place the leaves on a piece of squared paper (4mm²) and draw around them with a pencil.  Next count all the individual squares and record the numbers in a chart.  
  • Take the number of the squares for each leaf and multiply that number by 4.  (For example: 132 is the number of counted squares and multiplied by 4 it equals 528).
  • After calculating the area of each leaf, record the results in a table.
  • By adding the numbers together and then dividing that number by two, you will be able to calculate the mean of each leaf type.
  • Then using a ruler measure the length of each leaf but try to make it a fair test by either including or not including the small stem of each leaf.  Make sure that the measurements of length are all calculated in mm².
  • After that calculate the standard deviation of the area and then do the same for the length.
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Kettern 2

Data Collection:

Measures of Variation (Range):

Standard Deviation of Area:

Kettern 3

Then take the mean of Deviation² which is 27293 and square root it which equals 165mm².

Conclusion:

Group 1: 510

Group 2: 165

Group 3: 256

Group 4: 69

Group 5: 46

Comparing the standard deviation of the 5 samples shows that Group 1’s sample was more than 10 times more varied than Group 5’s sample.

Evaluation:

One of the limitations of this investigation was the sample size because more leaves ...

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