Which of the following DNA mutations is likely to have the most negative effect on the protein it specifies? A codon deletion at the end of a sequence
A base pair deletion resulting in a different amino acid
A substitution for one serine codon for a different serine codon
A substitution for one stop codon for another stop codon

Which best explains why viruses do not have special structures or enzymes that allow them to make their own food? viruses can use energy in living cells that they infect. viruses can replicate inside a host that they infect. viruses can cause contagious illnesses in host cells. viruses integrate their rna or dna into infected cells.

When does the circulatory system work with the respiratory system? a. during blood cell formation b. during cellular respiration c. during intestinal digestion d. during a viral infection

How can a geological time scale best be reconstructed? a) comparing vestigial structures in living species b) comparing homologous structures in living species c) examining homologous structures in fossil remains d) examining the written records of scientists from past cultures