Dna is composed of repeating structual units called

The structural units are called base pairs

Explanation:

They're called base-pairs, but if you want to get more specific, Base pairs are usually made of adenine, thymine, guanine, and cytosine.

dna is composed of repeating structure units called nucleotides

the transfer for conduction is the heat transfering from the liquid to the spoon

the transfer for convection is the heat rising from the liquid to the air

the transfer for radiation is the heat going through the sides of the cup and to the air

at least that is what i would do