called CF is a condition that causes excess mucus production in the lungs and if untreated causes early death. CF is caused by a deletion of 3 letters in the gene sequence. How might this deletion cause excessive mucus production?

The correct answer is - by absorbing too much sodium and water into the cells in the respiratory system.

Explanation:

Cystic fibrosis or CF is a genetic disorder that is caused by the presence of two defective genes that leads to the production of thick and sticky mucus in an individual that affects the respiratory and digestive system by clogging mucus in it.

Due to defective genes, there is an abnormal electrolyte transport system develops in which cells of the respiratory system including the lungs absorb an excessive amount of salt (sodium) and water. It all caused by deletion of the three letters which means an amino acid from a gene that leads to the disruption of the protein that controls the production of the mucus and abnormal electrolyte transport.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).