In hemoglobin, the shift from glutamic acid to valine is considered what type of mutation?

Point mutation

Explanation:

Change in single nucleotide of the DNA is referred to as point mutation. In hemoglobin, point mutation replaces the "adenine base" by "thymine" at the 17th nucleotide of the hemoglobin beta gene. This single nucleotide mutation replace the codon GAG (glutamic acid) to GTG (which encodes amino acid valine) and causes sickle cell anemia.

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation:

it cools slower in the earth meaning the crystals have more time to form than lava on the surface