LIFE SCIENCE

Detailed explanation-1: -DNA base pair. Under normal circumstances, the nitrogen-containing bases adenine (A) and thymine (T) pair together, and cytosine (C) and guanine (G) pair together. The binding of these base pairs forms the structure of DNA .

Detailed explanation-2: -Guanine and thymine are similarly incompatible. A always pairs with T and G always pairs with C because these are the only combinations that allow for hydrogen bonding to occur, given the spatial constraints of the double helix, which requires there to be one purine and one pyrimidine in each base pair.

Detailed explanation-3: -A unit of two bases in a molecule of DNA or RNA. In DNA, adenine always pairs with thymine (A-T), and guanine always pairs with cytosine (G-C). RNA is the same, except that adenine always pairs with uracil (A-U).

Detailed explanation-4: -Guanine binds with cytosine in DNA and RNA and forms three hydrogen bonds. This occurs because guanine has two nitrogen atoms and one oxygen atom that are able to form hydrogen bonds, so three bonds occur between these bases.

Detailed explanation-5: -The Adenine-Thymine base pair is held together by 2 hydrogen bonds while the Guanine-Cytosine base pair is held together by 3 hydrogen bonds. That is also the reason why the two strands of a DNA molecule can be separated more easily at sections that are densely populated by A-T base pairs.