I was thinking of finding the possibility of a tree
cancer. Looking at cancer as a cell that is defective,

Yes and no. The main defect in cancer cells is unregulated growth. If you use
the analogy of a tumor, rather than cancer, you can come up with an interesting
project. Plants, especially woody plants, do have the capability of producing
various kinds of galls, cankers, and excessive callous tissue, which are
similar to tumors and granulomas in animals. However, probably due to the
differences in the vascular system, I have never heard of gall tissue in a
plant metastasizing the way cancer metastasizes in animals. Also, while tumors
or cancer in animals are sometimes caused by infection or environmental
disturbance, & sometimes by a breakdown in the regulatory system, as far as I
know, the analagous growths in plants are always caused by the environment,
usually infection.
Go with it. You should be able to get photomicrographs of animal tumor cells
and comparable plant tumors, as well as animal and plant photographs, and some
illustrative live plants.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)