Alcohol,nicotine, and caffeine.
Because it determines if it is isolated or not. This means if other substances can enter or not. This usually relies on the membrane with it´s pores. The pores help the membrane be selectively permeable in what it lets in and out.
Answer:
Demography is the statistical study of human populations. Demography examines the size, structure, and movements of populations over space and time. It uses methods from history, economics, anthropology, sociology, and other fields.
I believe it is K or rather potassium
