MadSci Network: General Biology |
Susie, You seem to be asking two different questions here. The first question, Why do plants lose their leaves in the fall?, generally can be answered by saying that the leaves are shut off from the food supply. An abscision zone forms between the petiole and the stem cutting off the leaf from the plant. There are many things that can affect leaf drop in plants. Light, temperature, day length, and hormone concentration are all factors affecting leaf drop. A website you might want to check out is listed below: ht tp://www.nytimes.com/learning/students/scienceqa/archive/971118.html Your second question is a little vague. Are the big tree and little tree the same species? Do they both receive the same amount of light? Do they both have access to the same nutrients? Some trees lose their leaves very rapidly while others lose them more slowly. You need to make sure that both trees are the same species and are subjected to the same environmental conditions before you can answer this question. You can still do your experiment by asking the question, Will this big tree lose its leaves before the little tree?, and make a hypothesis. You could hypothesize: 1) The big tree will lose its leaves first 2) The little tree will lose its leaves first 3) The trees will lose their leaves at the same time Then, watch the trees to see how fast they lose their leaves to determine which hypotheses you have disproved.
Try the links in the MadSci Library for more information on General Biology.