List and describe at least two ways that similarity between organisms can be determined

1. Similarities/differences in analogous proteins

2. Comparison of DNA sequences

Explanation:

The similarities between a organism a based on their DNA sequences or amino acid sequences.they are closely related.  

Different species possess homologous structures such bones,or organs share both anatomical and  functional similarities Therefore an organism share homologous structures  have evolved from common ancestor. For instance,arm of a human being, limb of a horse,fin of  a fish, wing of a bird all are homologous structures and they perform similar functions.such as movement