Cellulose could provide an abundant and cheap form of glucose for humans. why is cellulose not a source of nutrients for humans? humans, and most vertebrates, lack the enzyme cellulase. human gut bacteria break down cellulose in the large intestine, after nutrient absorption occurs. animals use starch and glycogen as an energy source, whereas plants use cellulose for energy. humans cannot absorb the hydrolyzed form of cellulose. vertebrate enzymes hydrolyze (α 1–4) glucose linkages, but not glucose in the β configuration.

Achemical reaction (also known as a chemical change) produces substances that are chemically different from the starting materials. an example of a chemical reaction is the formation of water from hydrogen and oxygen gas.in a physical change, a substance changes its physical appearance but not its chemical identity. an example of physical change is the formation of liquid water from solid water, a familiar process called melting. physically, liquid water looks very different from solid water (ice) but the chemical identity, water, is the same for both. which of following changes that affect the composition of our atmosphere involve physical changes and which involve chemical reactions? oxygen gas changes to ozone during thunderstorms carbon dioxide is produced by the combustion of gasoline in an automobile engine. when coal, oil, and natural gas are decomposed in landsills they produce methane gas. freezing rain develops when a warm air mass overrides a cold air mass. fog forms from water vapor when the temperature drops below the dew point

Mike and mitchell decide to have a foot race. they mark off a stretch of 100 yards, and recruit cindy to work the stopwatch. after running the race and looking at the results, cindy declared that mitchell was the fastest. so how did the boys times compare?

Why is the structure of molecule important to its function?