Which of these is an agent of abrasion?
a. rock pieces
b. acid rain
c. high pressures
d. plant roots

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.

What is the main fuel source for the work of the cell

When a cell is in a solution that has the same concentration of water and solutes as its cytoplasm, the cell is said to be in a(n) solution. a. isotonic b. hypotonic c. hypertonic b. facilitated