What type of immunity uses cells and killer cells to identify and destroy abnormal cells?
a. congenital
b. humoral
c. cellular
d. innate

Which of the following is true of microbes? a. ninety-nine percent of all microbes are pathogenic.b. gene expression in bacteria is very similar to gene expression in humans, which facilitates the use of bacteria in recombinant biotechnology and gene therapy.c. all bacterial enzymes are harmful to humans and the environment.d. microbes create pollutants and toxins that harm the environment.

Ecology can best be described as the study of what

24. how are vaccines used to keep people healthy?