AP BIOLOGY

Detailed explanation-1: -Fallen leaves are recycled. After a leave has reached the ground, it begins to break down (with the help of animals, bacteria, and fungi), creating a layer of decaying organic material at the base of the tree. The leaf matter is converted back into simple carbon dioxide and water.

Detailed explanation-2: -It turns out autumnal leaf drop is a form of self-protection. While evergreen plants in cold climates have thick waxes and resins to protect their leaves from freezing and fracturing, deciduous species generally have thin leaves that are susceptible to cold temperatures.

Detailed explanation-3: -The changes in weather and daylight trigger a hormone that releases a chemical message to each leaf that it is time to prepare for winter. Over the next few weeks, abscission cells form a bumpy line at the place where the leaf stem meets the branch. And slowly, but surely, the leaf is “pushed” from the tree branch.

Detailed explanation-4: -During this season, the amount of sunshine falls and the production of the chlorophyll pigment in the leaves decreases until it completely stops. Consequently, the leaves change to a yellow or red color. Subsequently, the leaves dry out and fall because of a lack of color.