Describes hydrogen bonding in DNA?

Hydrogen bonds are created between the base pairs in DNA. Adenine pairs with thymine and cytosine pairs with guanine. Adenine and thymine create 2 hydrogen bonds while cytosine and guanine create 3. These bonds are fairly weak so that they can be broken when DNA is replicated (by an enzyme called helicase which unwinds DNA). However despite them being weak they do stabilize DNA's double helix structure as well.

Natural selection is when an animal does by nature like by natural causes or the weakest dies while the strong survive while artificial is only making the best traits survive not naturally and keeping the ones with the best traits alive