Answer:
genetic drift
Explanation:
Genetic drift is an evolutionary force that requires the presence of a small population. It is a random process that fixes one or other alleles randomly in the gene pool of a population. Genetic drift does not take account of survival fitness imparted by alleles to the individuals. Since random and chance events such as the death of all the individuals having a certain allele in a population affect the small population more intensely, genetic drift works on small populations only.
A tetrad consists of 2 homologous chromosomes each of which is made up of 2 sister chromatids
1. an atom
2. compound
3. both
4. atom
