What is a point mutation? and what are the two consequences?

A point mutation is a mutation that takes place at a particular point in which one base pair in the DNA sequence is altered. During DNA replication is when point mutation usually happens. It causes change in chemical structure of gene or chromosome.

The two consequences can either be either a beneficial or a harmful (catastrophic) type of point mutation. In the gene the point mutation involves substitution, addition, deletion of a single nucleotide. The altered gene structure sometimes create a positive impact clearing the negative one unfortunately this point mutation that occurs brings fatal diseases.  

the answer is b.) hydrogen bonds between bases.

the correct answer is b