Which of the following is true about a polar amino acid and cellulose?
a. both are polysaccharides.
b. both contain nitrogen.
c. both are hydrophobic.
d. both contain hydrogen atoms.

Which of the following birds remained ancient looking in the miocene epoch? a. crows b. owls c. grouses d. none of the above

Read each description below and determine to which stage of sleep each pertains. then click and drag each box into the appropriate category below.

Which of the following matches the organisms described with the correct domain? a. archaea--multicellular, eukaryotic organisms that do not have cell walls b. eukarya--single-celled and multicellular organisms, with a defined nucleus and a variety of nutritional sources c. bacteria--unicellular, eukaryotic organisms with cell walls that do not contain peptidoglycan d. bacteria--unicellular, eukaryotic organisms that always lack cell walls