Home >> Science & Nature >> Science

Science Projects on How Gravity Affects Plant Growth

Seeds sprout stems that grow upward and roots that grow downward. For example, plants on a hill don't grow perpendicular to the ground --- they grow in the same vertical direction that plants in flat ground grow. This is due to auxin, a chemical present in plant cells that makes such cells elongate. Stems respond to gravity by growing against its force; root cells, in contrast, respond by growing with the gravitational pull. Geotropism, or the effects of gravity on the way plants grow, can be tested and documented in various ways.

Change Direction
- Take several single sheets of paper towel and wet it. Place seeds or beans on the paper towel and place it in a sealable plastic bag. As you close the bag, leave a slight opening to allow air to circulate. Leave the bag on a horizontal surface, moving it only enough to add water as needed. When the seeds sprout, move them 90 or 180 degrees each day and document what happens to each seedling.
Turn the Tables
- Simulate gravity's pull by using a record player or turntable. Prepare the seeds or beans as before and tape the bag to the turntable's base. Set the turntable for 78 rotations per minute (RPM) and allow it to run for five days. Leave the bag in position and cut it open to observe the seedlings and how they have grown. You can alter this experiment by changing the RPM setting and documenting whether or not the results differ.
Radish Cups
- Fill several clear plastic cups with soil and place a radish on top of the soil in each cup. Change the position of the radish in each cup: root end pointed down, root end pointed up, and on its side. Water until moist and continue watering daily. Document how the roots and sprouts form and how they grow.
Bean Angles
- Create four strips of paper towel by folding squares of paper towel four times lengthwise. Lay four pinto beans, each in the same configuration and equally spaced apart on each strip, for a total of 16 beans. Gently roll each strip up and tape it to a square of cardboard. On each square, draw an arrow above the beans pointing upward. Moisten each roll with water and place each square in a sealable plastic bag. To allow air to circulate, do not seal the bags all the way. Pin each bag to a bulletin board, placing them with arrows pointing outward: up, right, down, and left. Keep all rolls moist. Monitor the beans' germination and document how the stems and roots grow.

Science