the+Big+idea

PAGE 632 CH.25!!!!! TROPISMS,PHOTOROPISM ===Phototropism is a big idea in our project, it is the responce of the plant to light. Phototropism causes the plant to grow torwards the light source, which is what we are working with. Which leads to Photoperiodism, were the number of hours of light and darkness effects the plant. Researchers found out that many plants respond to periods of light and darkness. This conntects with the plants hormones. in plants the division, growth, maturation, and development of cells are all controlled by hormones.=== Plant Hormones: chemical substances that control a plants patterns of growth and devopment, and the plants responces to enviromental conditions.

===The hormones moves through the plant from the place were it is produced to the place were it triggers its responce. Tropism is when a plant changes its pattern and direction of growth in responce to a multitude of cues. TROPISM comes from a greek word which means "turning". the Tropism is one of the main ideas in our project because it includes, gravitropism ( the responce of a plant to the force of gravity), Phototropism, and Thigmotropism ( which is the responce of a plants to touch). Thigmotropism may be a problem to our investigation, since we are mesuring only the light source, it may be a problem that we dont mesure other things also, like how much we touch the plant. A plant that is touched reguarly, stunts the growth. (we did not know this before so we will have to write this in our observations.)=== Another major idea is Auxins, they are located on the upper part of the stem. they controll and coordinate how the plant grows. The auxins generally move torwards the spot on the stem that is most shady, and causes it to bend torwards the light.