Experiment: Phototropism (growth in the direction of light)

Objectives:Investigate the effect of light on root and stem growth

Materials:Petri dishAluminium foilFilter paperLentils

Procedure:1. Place two circles of filter paper inside the Petri dish, taking care to ensure

that the paper is touching the edges2. Moisten the paper with a small amount of water and place the lentils as

indicated.3. Moisten two pieces of filter paper and then cover the lentils with them. Cut a

circular piece of aluminium and place it on top of the filter paper. Put the top on the Petri dish.

4. Put the Petri dish in a light place, however, the area shouldn´t receive direct sunlight. Leave it in the same place for three or four days.

Results:1. After three or four days, remove the

Petri dish´s cover, taking care not to alter the position of the seeds. Observe the development of the roots and stems.

2. Make a drawing of what you have found in the Petri dish.

Questions1. Why did you moisten the filter paper?2. Why did you cover the seeds with the

paper?3. Do the seeds receive light?4. Did you observe any relation between

the light and the development of the roots and stems? Explain this.