Answer:
Mutation
Explanation:
A Mutation alters the genetic message carried by that gene as there are permanent changes in the nucleotide sequence of DNA or a DNA gene.
This can occur by base pairs substitution, deletion or insertion
Simple. Air has mass. And if air has mass it also has weight. You can feel air when the wind blows. Or do an experiment. Weigh an empty container. Then pump it to a vacuum. Weigh it again. The difference is the weight of the air inside.