What 3 things make up a nucleotide (unit of DNA/RNA)?

How does the molecular clock work? a. it analyzes the brain functionality of two different species.b. it examines and compares the physical characteristics of two different species.c. it illustrates relationships between two different species.d. it compares the number of mutations that exist in the dna of two different species.

All individuals have two alleles for a given trait. according to mendel's these alleles are passed down one each from both mother and father.

Stephen is a student who wants to test his knowledge of medical terminology. which option could he use?