(i need this answer quick fast and in a hurry. i'm on a cumulative exam)which element is most important for adding strength to hair, feathers, and outer skin? a. oxygen b. hydrogen c. sulfur d. phosphorus

Which kind of aquatic ecosystem does the photograph most likely show? a. marsh b. swamp c. lake d. river

What is the significance of the protein-lined pits? a. protein attracts other proteins needed for atp synthesis within the cell. b. protein-lined pits are able to transport one molecule at a time down the concentration gradient within the cell. c. the polarity of proteins allows other polar molecules to attach and be transported in the cell by transport channels. d. receptors within the pits allow ligands to fuse and be transported into the cell by endocytosis.

The most famous fossil called archaeopteryx is which of the following? a dinosaur a fern a fish a bird