After the bases of DNA were identified, Erwin Chargaff analyzed the percentages of adenine, thymine, guanine, and cytosine in the DNA of many different organisms. This table shows the percentages of A, T, G, and C for a human, a bacterium, and a fish. Chargaff observed an approximate rule about these percentages in all of his samples: What is the rule?

A.
A + T = G + C

B.
A = G; T = C

C.
A = C; T = G

D.
A = T; G = C

D) A = T; G = C

Explanation:

Chargaff's rules state that "DNA from any cell of any organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine should be equal to cytosine and the amount of adenine should be equal to thymine".

This pattern is noticed in the DNA strands.

the answer is a) cell division.

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blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.