The sliding filament model of contraction involves:

a. actin and myosin sliding past each other and partially overlapping
b. the shortening of thick filaments so that thin filaments slide past
c. actin and myosin shortening but not sliding past each other
d. the z discs sliding over the myofilaments

b is dominant over the allele for the white fur.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.

photosynthesis makes the glucose that is used in cellular respiration to make atp. the glucose is then turned back into carbon dioxide, which is used in photosynthesis. while water is broken down to form oxygen during photosynthesis, in cellular respiration oxygen is combined with hydrogen to form water.