The ocular micrometer has no units. Revolving Nose Piece - Several objective lenses of varying magnification and numerical aperture are mounted on the revolving nosepiece. The nosepiece must click into place for the objective lens to be in proper alignment.
What happens to the population density and competition if the birth rate decreases? The birth rate would increase is the population density competition increased. Hope I helped.
True, the plasma membrane is selectively permeable and controls the various substances that are allowed into the cell and that are allowed to leave the cell.