What Drives a Seed

The Objective : Are seeds driven by Gravity (Geotropism) or by Light (Phototropism)?


1. You must germinate your bean seeds by placing the seeds in a damp paper towel. Put this in a warm place for 2-3 days. If the paper towel starts to dry out add more water.

2. While your seeds are germinating you must make a place to put your seeds. I chose to make mine out of
cardboard. With slots to put the Petri dishes in.

3. Stretch three cotton balls across the smaller half of each Petri dish.

4. Put 30 ml. of water on the cotton in each Petri dish.

5. After your seeds are germinated place one seed in each of the 24 Petri dishes. 12 of the seeds are placed up-side-down and the other 12 right-side-up.

6. Place the Petri dishes in the prepared holders.

7. Put one holder in a box with the light under the trays, one tray with the light above and one tray with the light to the side. The last tray of six dishes will be in a box that gets no light.

8. Leave the boxes for one day and take pictures the next.

9. Take pictures every other day until the seed's shoots reach the top of the Petri dish.

10. Repeat all steps with corn seeds.

MATERIALS LIST:30 or more Corn and Bean Seeds, 1 Adult to help, An Exact-o-knife Card board, 1 role of duct-tape, 3; 18# fluorescent tube lights, 1 blanket, 72(100%cotton) Cotton balls, 24 Petri dishes, 1 large bowl of water, A measuring devise of 30ml. (liquid), A measuring tape or yard stick


The results of this project were that regardless of the position of light or lack of light the stems of both corn and bean seeds grew opposite of gravity and the roots pointed down or with gravity.


In conclusion the seeds all ended up being geotropic. This means that my hypothesis was incorrect. Roots of bean and corn seeds grow with positive geotropism and stems grow with negative geotropism. Meaning roots go toward gravity or downward and stems grow away from gravity or upward. The direction the light came from did not affect the direction of the growth of the stems or roots of the seeds. They are driven by gravity alone!

This project is about finding out if seeds react to light (phototropism) or gravity (geotropism) or both when growing.

Science Fair Project done By Ciara A. Dwyer



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