Driving automobiles and burning coal for electricity are examples of two human activities that negatively impact 

  a. 

the rock cycle

  b. 

air quality

  c. 

the flow of water

  d. 

erosion

Which of the following statements about archaea and bacteria is true? a. neither is single-celled. b. they both have nuclear membranes. c. neither reproduces by binary fission. d. they both lack a nuclear membrane.

Which description provides the best objective summary of the article in the passage?

Describe the structure of amino acid, including what makes amino acids different from eachother