Bob was doing an experiment to see what affects the growth of tomato plants. Bob uses a different fertilizer in each of the experimental groups. He keeps everything else constant. Each day, Bob measures the growth of the plants. The height of the tomato plants represents what in the experiment?

unicellular organisms, like bacteria, are able to perform all life functions within one single cell. multicellular organisms need many different types of cells to carry out the same life processes. each of these special types of cells has a different structure that it perform a specific function.