So they know for sure their answer is correct before they move on.
Attached are two images concerning DNA.
The first image is a diagram that illustrates the base paring of DNA. First, there is the ribose-phosphate backbone that keeps the DNA together. Then the bases thymine and adenine are joined together by two hydrogen bonds. On the other hand, the bases guanine and cytosine are joined together by three hydrogen bonds.
The second image shows the helical structure of the DNA.
<span>If the number of electrons is less than the number of protons, the particle is a positive ion, also called a cation.
</span><span>If the number of electrons is greater than the number of protons, the particle is a negative ion, also called an anion.
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hope I helped...