Chapter Questions
Some people claim that life's high degree of organization defies the physical law that says that entropy always increases. What makes this statement false?
List some examples of energy-requiring and energy-releasing reactions that have been introduced in previous chapters.
Why is ATP called the cell's "energy currency"?
In what ways is an enzyme's function similar to engineers digging a tunnel through a mountain rather than building a road over the peak?
Use what you know about enzymes to propose an explanation for why our bodies cannot digest the cellulose in dietary fiber. Also, why would a cell's fat-digesting enzymes not be able to digest an artificial fat such as Olestra (see chapter 2 )?
Considering that enzymes are essential to all cells, including microbes, why might refrigeration and freezing help preserve food?
When a person eats a fatty diet, excess cholesterol accumulates in the bloodstream. Cells then temporarily stop producing cholesterol. What phenomenon described in the chapter does this control illustrate?
Diffusion is an efficient means of transport only over small distances. How does this relate to a cell's surface-area-to-volume ratio (chapter 3 )?
Liver cells are packed with glucose. If the concentration of glucose in a liver cell is higher than in the surrounding fluid, what mechanism could the cell use to import even more glucose? Why would only this mode of transport work?
List three ways the content in this chapter relates to an organism's ability to maintain homeostasis.
Golden knifefish use an electric field to detect nearby objects and to communicate. Scientists know that ion channels in the membranes of the electric organ cells are largely responsible for generating the electric field. They also know that knifefish can quickly turn up or turn down the intensity of the electric field. What type of membrane transport might the knifefish use to quickly increase the number of ion channels in the cell membranes of its electric organ? What process would remove ion channels from the cell membranes?