A bird flies by moving its wings up and down. Which two systems are most directly responsible for the movement of a bird's wings? A bird flies by moving its wings up and down. Which two systems are most directly responsible for the movement of a bird's wings?
A.
respiratory and muscular systems
B.
skeletal and digestive systems
C.
respiratory and digestive systems
D.
skeletal and muscular systems

How does a lytic infection differ from a lysogenic infection?

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?