Asmall population of a specific bird species lives on an island in the pacific ocean. all of the birds of this species have a crest of feathers on their heads. the color of the crest can be orange, yellow, or white. an individual's crest color does not effect its chance of survival or its reproductive success. a hurricane hits the island and all of the birds with orange crests are killed, as well as many of the individuals with yellow and white crests. this causes the gene for orange crests to be lost from the population. the loss of the gene coding for an orange crest in the bird population described above is an example of

Genetic drift

Explanation:

Genetic drift  is an evolutionary mechanism that changes the allele frequency by random sampling (by chance). This type of mechanism has the major impact when population is hit by a natural disaster. As a consequence, the population becomes reduced in size and some alleles might be lost (such as that for  for orange crests). The genetic variability is decreased.

enzyme active site and substrate specificity

enzymes bind with chemical reactants called substrates. there may be one or more substrates for each type of enzyme, depending on the particular chemical reaction. in some reactions, a single-reactant substrate is broken down into multiple products