# An Investigation To Discover Whether Or Not There Is A Relationship Between Light Intensity And The Surface Area Of A Leaf.

Essay by HelsinkiHigh School, 11th grade March 2004

The aim of this investigation is to see whether I can find a definite relationship between the light intensity onto the leaf's surface and the surface area of the leaf.

Hypothesis

I think the light intensity could affect the surface area in the following way:

ÃÂ·A higher light intensity could make the surface area of the leaf larger.

The reason I think a higher light intensity could make the surface area larger is the fact that there would be a larger amount of chlorophyll, containing chloroplasts, for photosynthesis. By having leaves of a larger surface area, there would be a much more efficient use of the chloroplasts (containing chlorophyll) and the high intensity light available.

Apparatus

In order to carry out this experiment we will need:

ÃÂ·A light probe

ÃÂ·A graphing calculator

ÃÂ·A ruler

Method

ÃÂ·Connect the light probe to the graphing calculator

ÃÂ·Program the graphing calculator to deal with light probes

ÃÂ·Place the light probe in the middle of four leaves.

ÃÂ·Make sure the light probe is pointing in the same direction as the leaves and is facing away from the leaves

ÃÂ·Take the light intensity reading and put it in a table of results

ÃÂ·Measure the length and width of each of the four surrounding leaves and record these results

ÃÂ·Repeat the test 15 times, trying to get a wide range of light intensities.

To make this test a fair test, I will have to control several variables. These are the temperature, the age of the leaves and the nourishment of the leaves.

To control the temperature I will be carrying out the investigation on the same day, in as short a period of time as possible.

By using the same hedge throughout the investigation, I should be able to ensure that the leaves are getting the same...