In the pairing of nitrogen bases, which base always pairs with cytosine? Adenine
Guanine
Thymine
Pyrimidine

Explanation:

In genetic material (DNA-deoxyribonucleic acid and RNA-ribonucleic acid) there are nitrogen bases.

Recall that DNA has a "double helix" structure that mimics a ladder. The base pairs make up the rungs of the ladder. In RNA there are bases, but it is single stranded, so no ladder rungs.

In DNA, the bases pair like so:

In RNA there is no thymine and instead uracil, so the bases pair like so:

In both DNA and RNA, cytosine always pairs with guanine.

why do the isotopes of a particular element behave differently in nuclear reactions but the same in chemical reactions? chemical reactions involve changes to electrons in an atom; isotopes do not differ in electrons, and so they react the same way during chemical changes.

< > according to newton's third law of motion, forces always act in equal but opposite pairs. another way of saying this is for every action, there is an equal but opposite reaction.< >