What is the main source of energy?

In dna, only the_ varies from one nucleotide to another. base phosphate sugar amino acid

Ialready know the answers to these questions and they are on the attachment. but i just need to know why that answer is the correct one. plz asap! this is for a report that i need to email by 10!

Which of the following situations describes a adaptation for a mole? question 2 options: a mole is blind and cannot see underground. a mole is bright and attracts the attention of predator birds. a mole has a sensitive sense of smell to it find food underground.