What instrument was necessary before the cell theory could be developed?

Plz ! a frog has a genetic mutation in skin cells that causes part of its skin to turn orange the frog will not pass this genetic mutation onto its offspring because, a. the offspring will inherit skin cells from the other parent. b. mutated skin cells cannot divide and produce daughter skin cells. c. skin cells do not contribute genetic material to sex cells. d. parents do not contribute genetic material to their offspring.

Construct at least two possible hypotheses for the student’s experiment.

Veins have a much lower blood pressure than arteries. which of these prevents backflow of blood in veins? a. pressure applied by the heart b. one–way valves in veins c. thin muscular walls of veins