Chapter Chapter 5: The Working Cell
 
Pre-Lab
 

1 .       Energy is observed in two basic forms: potential and kinetic. Which of the following is an example of potential energy? (5.1) [Hint]

 waves crashing against the shoreline
 a hot cup of coffee
 a bowling ball placed on the top shelf of a closet
 the mercury rising within a thermometer
 a car rolling downhill
2 .       According to the second law of thermodynamics _____. (5.2) [Hint]

 life should be impossible
 the quality of energy in the universe is constant
 the quantity of usable energy declines with each energy transformation
 it is not possible to observe an increase in molecular organization
 energy can neither be created nor destroyed
3 .       Which of these reactions is endergonic? (5.3) [Hint]

 the cooling that results from water mixing with urea
 the heating that results when water mixes with sodium hydroxide
 the burning of wood
 the generation of light by fireflies
 none of the above
4 .       The molecule most directly involved in energy transfer within cells is ____________. (5.4) [Hint]

 ATP
 O2
 CO2
 NH3
 CH4
5 .       Enzymes are described as catalysts, which means that they _____. (5.5) [Hint]

 are proteins
 provide activation energy for the reactions they facilitate
 change the rate of a reaction without being consumed by the reaction
 can make an endergonic reaction exergonic
 elevate the activation energy barrier so the molecules will not spontaneously degrade
6 .       What best explains the observation of substrate specificity? (5.6) [Hint]

 There is a precise compatibility between an enzyme's active site and the substrate molecule.
 Specificity refers to the action of the enzyme, such as hydrolysis, and relatively few molecules can be hydrolyzed.
 Molecules and active sites vary in size; only properly sized molecules can fit.
 Reaction-specific enzymes assume a fit by folding around the most numerous substrate molecules.
 Polarity compatibilities: Active sites contain electronegative atoms, while substrates tend to carry slight positive charges.
7 .       Phospholipid molecules in a membrane are arranged with their ____ on the exterior and their ____ on the interior. (5.11) [Hint]

 hydrophobic heads ... hydrophilic tails
 hydrophilic heads ... hydrophobic tails
 nonpolar heads ... polar tails
 hydrophobic tails ... hydrophilic heads
 hydrophilic tails ... hydrophobic heads
8 .       The movement of molecules from an area of higher concentration to an area of lower concentration is called _____. (5.14) [Hint]

 diffusion
 endocytosis
 phagocytosis
 active transport
 osmosis
9 .       In osmosis, water always moves toward the ____ solution: that is, toward the solution with the ____ solute concentration. (5.16) [Hint]

 isotonic ... greater
 hypertonic ... greater
 hypertonic ... lesser
 hypotonic ... greater
 hypotonic ... lesser
10 .       The concentration of calcium in a cell is 0.3%. The concentration of calcium in the surrounding fluid is 0.1%. How could the cell obtain more calcium? (5.18) [Hint]

 passive transport
 diffusion
 active transport
 osmosis
 any of the above