How would a decaying tree be classified

The answer is non-living and biotic. Non-living because the processes that characterize a living organism (such as respiration, growth, response to stimuli, nutrition, and etcetera ) cease in the tree. Biotic because the tree is still composed of molecules associated with life such as proteins, carbohydrates, cellulose, lignin, and etcetera, even though the tree is dead.

answer: the blood-brain barrier is a layer of specialized membranes and cell processes designed to keep undesirable substances from passing from the bloodstream into the precious tissues of the brain. while the blood-brain barrier does keep most bad things out of the central nervous system, it is not impermeable.

explanation:

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.