The X-ray crystallography data suggested DNA is double stranded and has a uniform diameter. These observations can be used to rule out base pairing between two of the same nucleotide because .

an A- A pair is wider than a CC pair.

Explanation:

One of the great scientists that worked on how the structure of Deoxyribonucleic acid is is the chemist called Rosalind Franklin. The Deoxyribonucleic acid can be divide into three main, namely: the nitrogen base[ that is the adenine, guanine, cytosine and the thymine], the phosphate and the deoxyribose.

From Franklin's work, it was shown that the Deoxyribonucleic acid is a structure composing of double helix with both having the adenine, guanine, cytosine and the thymine. The diameter will not be the same because there is the case of Adenine- Adenine being wider than Cytosine- Cytosine.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.