Why do some leaves turn yellow and others red in the fall?

Answer 1

In various trees, certain amount of various chemical compounds exist. But the colors of these chemical compounds are obscured by the chloroplasts that make for a green color. Then as the end of the summer season approaches, the deciduous trees reclaim those parts in the leaves that are needed for later amd most of the chloroplasts die. It is at this time that the other colors are able to be seen. Those chemical compounds were always there, just not visible because of the chlorophyll. With the chlorophyll gone, they then become visable a few weeks before the leaves are shed. In evergreen trees (firs, and other plants that do not regularly shed leaves) those chemical compounds are there as well, but because they never shed their "leaves" in any dynamic display, we pretty much never see any color but green. Helpful??

Answer 2

The color you see on the leaf is actually the color in the light spectrum (between 400-800 nanometers in lenght) that is NOT being absorbed by the leaf. So, chlorophyll actually uses the other "colors", which are actually the different lengths of light waves (the shorter, the more blue...the longer the more red). So when you see a leaf turning yellow or red it is because the other light rays are now being used to aid in photosynthesis and different pigments are being used. Each pigment has it's own range of aborbance and reflection...

Answer 3

it depends if the tree has alternative use for the chlorophill.. if it does the tree sucks it back in and the leaf falls whilst losing colour.. if not it will turn a yellow

Answer 4

leaves have 4 pigments-chl a,chl b, carotene and xanthophyll.In leaf fall chl degrades and if carotene is dominant it turns red,if xanthophyll is dominant it turns yellow.

Answer 5

Because of the PH of their sap.

Answer 6

I though they turned yellow, then red, then fell off. Dunno, bet we'll get a great answer from someone!!!