Which is the best definition of a prokaryotic cell? it has a cell wall but lacks a well–defined nucleus and organelles, and its cytoplasm doesn't have much structure.
it contains a membrane–bound nucleus and organelles, and its organelles have specialized duties.
it contains a membrane–bound nucleus, a large central vacuole, a cell wall, a cell membrane, and chloroplasts.

Match the examples to the correct level of organization. 1. system level roses, snakes, puppies 2. organism level roots, stamens, leaves 3. tissue level bone, cartilage, blood 4. organ level heart, veins, arteries

1. variations in a population of moths allow for some of its members to be able to adapt to environmental changes. the better adapted of the moths will be able to survive the change and thus prevail as the “fittest” of the species. (a) describe three mechanisms in which variation can occur within a species population. (b) explain which mechanism or mechanisms would be responsible for the survival of a population of peppered moths better than white moths in an environment affected by industrial soot. justify your answer.

If a strand of dna has 35% thymine. what is the percentage of cytosine, adenine, guanine?