Coursework

What is photosynthesis?

Photosynthesis is a process used by plants and other organisms to change light energy, usually from the sun, into chemical energy that can be re-used. Most plants perform photosynthesis, such organisms are called photoautotrophs. Photosynthesis keeps atmospheric oxygen levels and supplies all of the organic compounds and most of the energy necessary for life on earth.

The equation for photosynthesis [pic 1]

Plants absorb water through their roots an also absorb carbon dioxide through their leaves. Some of the glucose is used for respiration and is changed into insoluble starch for storage. The remaining starch can later be turned back into glucose and used in respiration. Oxygen is released as a side product of photosynthesis  

Investigation purpose:
The purpose of my experiment is to find out how light intensity affects the rate of photosynthesis in pondweed. To do this I will place the light intensity to various distances and observe the amount of oxygen bubble given off from the reaction.

Hypothesis:

The hypothesis that as the light intensity increases the rate of photosynthesis will increase and as the light intensity decreases so will the rate of photosynthesis.

Prediction:
I predict that as the light intensity increases, the rate of photosynthesis will also increase until a certain level is reached. After, the rate of reaction will then fall. In the end the increase in light intensity will no longer affect the rate of reaction. This is because other factors affecting rate of reaction will be limited for example: carbon dioxide and temperature.


Preliminary work 
to check if the range that I chose for my experiment were correct I carried out a preliminary investigation in which I counted the amount of oxygen bubble given off from the reaction at several distances in a given time. To adjust different light intensity I used a lamp at various distances from the reaction of the pondweed. I used the meter ruler to measure the various distances from the plant.

Equipment list:

Retort Stand: To hold the test tube in place

Test tube:  To contain the pond weed and the water

Lamp: To give the pond weed light to make photosynthesis happen

Pond weed: To prove that photosynthesis happens in plants

Ruler: To measure the distance between the light and the pond weed

Water: To show that photosynthesis happens and to contain the pond weed

Timer: To time how long the experiments are

Risk Assessment: