The purpose of the cell membrane is to hold the different components of the cell together and to protect it from the environment outside the cell. The cell membrane also regulates what enters and exits the cell so that it doesn’t lose too many nutrients, or take in too many ions. It also does a pretty good job of keeping harmful things out.Ions and large polar molecules cannot pass through the lipid bilayer. But more specifically, whether a molecule can pass through the membrane depends on its size and its electrical nature. The membrane is highly permeable to non-polar (fat-soluble) molecule.
Answer;
Gene flow
Gene flow is the most important factor that holds a gene pool of a species together and prevents speciation.
Explanation;
-Evolution may occur as a result of genes being transferred from one population to another. This gene flow occurs when there is migration. The loss or addition of people can easily change gene pool frequencies even if there are no other evolutionary mechanisms operating.
-Gene flow may also occur without migration, for instance, when people travel to another area and successfully mate with people in the population there, a transfer of genes occurs between the populations even though the traveler returns home.
-Additionally, gene flow may flow between species. A good example is when segments of DNA are transferred from one species to another by viruses as they invade the cells of animals or plants.
An object will remain at rest until an unbalanced force acts upon it, this basically means that if someone were to kick a still soccer ball, then it shall move from its resting place :)
