Biology Projects on the Effects of the Intensity of Light on Flowers

Project Preparation

• Take nine flowering plants of the same age, type, and stage of flowering. Build a cabinet with nine compartments, each of equal shape and size. The cabinet can be made out of any sturdy material that will block light, but wood is easiest to obtain and to work with. In each cabinet, install a lamp or lightbulb with an individual dimmer switch you can control. Place the plants in their compartments. It is important to make sure the compartments are sealed from any other sources of light.

Conduct the Experiment

• In three compartments, set the dimmer switch to full. In three other compartments, set the dimmer switch to 50%, or in the middle. In the final three compartments, set the dimmer switch to approximately 10%. Make sure to have three separate compartments of equal intensity. Using three plants for each intensity level helps maintain the integrity of the project and control for anomalous data. Make observations and take photographs over a period of one week.

Analyze Your Results

• Note any differences in the plants and flowers, and analyze the data to see if there is a correlation between the level of light and the appearance of the flowers. The plants that received the most intense light will likely have leaves of a darker green. They may appear healthier, but shorter and with sturdier branches. The plants that received the lowest light intensity are likely to be a brighter green color, and appear to have thinner, weaker branches. Count the number of flowers or flower buds on each plant and note the type of light each plant received. Also note the appearance of the flowers.

Light and Metabolism

• All living things need energy to power their basic functions. Animals obtain their energy from food. Food is broken down into energy by a process called "metabolism." Similarly, plants use a process called photosynthesis to convert light energy to usable energy. Flowering plants, like all plants, contain a chemical called chlorophyl to convert the light to chemical energy, which the plants use for their fuel.

Light and Plants

• Different plants require varying intensities of light and different lengths of exposure to fuel their metabolisms. Try using different variables, such as the amount of time the plants are exposed to light. You can also try changing the color of the light to see whether plants respond to different colors.