Which enzyme is responsible for unzipping the dna double helix?

The enzyme that untwists and unzips the double helix of DNA at the replication forks is called helicase, A protein that functions in DNA replication, helping to relieve strain in the double helix ahead of the replication fork.

Exercise increase the rate at which energy is needed from food, increasing the need for both food and oxygen by the body .this is why when we doing exercise both pulse/heart rate and breathing rate increase. when we doing exercise the pulse rate is an indication of your heart rate as you arteries expand each time the ventricles pump blood out of the heart.