Dynein is missing from the cilia and flagella of individuals with a specific inherited disorder. These individuals have severe respiratory problems and, if males, are sterile. What is the structural connection between these two symptoms?

Cells lining the trachea have whiplike motile extensions on their free surfaces. What are these extensions, what is their source, and what is their function?

Microvilli are found

(a) Mostly in muscle cells

(b) On the inside of plasma membranes

(c) In large numbers on cells that secrete hormones

(d) In cells that are actively engaged in absorption

(e) Only on cells lining the reproductive tract

What component of the cytoskeletons do motor proteins use to transport vesicles?

In human cells, ___________________ are used to move a cell within its environment while ___________________ are used to move objects in the environment relative to the cell.