I believe the answer is a definition.
The answer is: Survival of the form that will leave the most copies of itself in successive generations.
"Survival of the fittest" is a phrase that originated from Darwinian evolutionary theory.
This is example of natural selection and adaptation.
Genetic variation is important to the population's ability to survive in different situations that affect natural selection.
The environment is constantly changing and different alleles are favored.
Polar covalent bond- a bond where atoms are unevenly shared due to a larger difference in electronegativity of the bonded elements.
Non-polar covalent bond- These are bonds between elements with a low difference in electronegativity. Electrons are shared equally in these bonds between the elements.
Ionic bonds- have such large difference in electronegativity that they take/give electrons to the element they are bonded to. They do not share electrons at all. Bonds between a non-metal and a metal.