All living organisms are composed of

a. only one cell.
b. at least three cells.
c. at least 100 cells.
d. one or more cells.

Chlorophyll is found in plant leaves and absorbs light from the sun to enable plants to perform photosynthesis. magnesium is an important component of chlorophyll. the concentration of magnesium ions is higher in the root-hair cells of plants than in the soil. which mechanism of ion uptake would best enable a plant to produce a steady supply of chlorophyll? osmosis diffusion passive transport active transport

In this experiment, the was intentionally manipulated. it is the independent variable. the dependent variables that were measured were the

In many humans, exposing the skin to sunlight over prolonged periods of time results in the production of more pigment by the skin cells (tanning). this change in skin color provides evidence that -