On the outside of the plasma membrane? acts as signals or makers to cells recognize one another

Outside the plasma membrane there is presence of glycoprotein which is a series of polysaccharides to form the cell coat and is used for ID or cell recognition. Each individual has a unique special code for the glycoprotein.

•there must be variation for the particular trait within a population.

•the variation must be inheritable (that is, it must be capable of being passed on from the parents to their offspring).

•individuals with one version of the trait must produce more offspring than those with a different version of the trait.good

explanation:

a ratio derived from the equality between two different units that can be used to convert from one unit to the other. information obtained from experiments, sometimes called experimental results. the part of the experiment that is affected by the independent variable.