The Effect of Light Intensity on the Rate of Photosynthesis in an Aquatic Plant

The Effect of Light Intensity on the Rate of Photosynthesis in an Aquatic Plant

Introduction

The input variable I will be investigating is light, as light is just

one of the 4 factors required in the green-plant process of

photosynthesis. Photosynthesis is the process by which green-plants

use sunlight, carbon dioxide, water & chlorophyll to produce their own

food source. This process is also affected by the temperature

surrounding the plant (the species of plant we experimented with, pond

weed, photosynthesised best at around 20 degrees centigrade.)

Light, temperature & CO2 are known as limiting factors, and each is as

important as the next in photosynthesis. Light is the factor that is

linked with chlorophyll, a green pigment stored in chloroplasts found

in the palisade cells, in the upper layer of leaves. The light is

absorbed by the chloroplasts to produce the chlorophyll. The chemical

& word equation for photosynthesis is stated below:

Sunlight

Carbon dioxide + water -----------------> Glucose + oxygen

Chlorophyll

S

6CO2 + 6H20 -----------------> C6H12O6 + 6O2

C

Light in photosynthesis

Photosynthesis cannot take place without light, as light is one of the

factors by which the green plant photosynthesises (makes its own food

source) Light provides the plant with energy to make the chlorophyll

which in turn absorbs the light. From this it can be said that the

more light a plant is provided with (the more of a limiting factor is

takes in) then the higher the rate at which the pond weed, or any

plant, will give off a product of photosynthesis i.e. glucose or

oxygen. From this the knowledge can be gained that depriving the

aquatic plant I will be investigating of all light would be a

pointless investigation, as no outcome could be measured. Instead I

will vary the light intensity the plant is provided with. I will do

this by placing the light at different distances from the aquatic

plant. I also thought about varying the wattage of the lamp I will be