Which of the following is NOT a function of proteins?

The portion of the plasma membrane that generates a barrier?

• 1) The portion of the plasma membrane that generates a barrier preventing the passage of most molecules across the membrane is a) phospholipid bilayer b)cholesterol c)proteins d)carbohydrates e)nucleic acids 2) Which of these statements regarding enzymes is false? a)enzymes are proteins that function as biological catalysts b)enzymes display specificity for certain molecules to which they attach c)enzymes provide energy for the reactions they catalyze d)the activity of enzymes can be regulated by factors in their environment e) an enzyme may be used many times over for a specific reaction 3)which of the following has potential energy a) a water droplet on top of a waterfall b)a glucose molecule c)a diver on a springboard d)a 9v battery e) all of the above 4) In an isolated syste, all the following are true of the second law of thermodynamics except a)useful energy decreases b)spontaneous changes result in more uniform distribution of energy c)all chemical reactions are exergonic d)there is a natural tendency toward greater disorder of the organization of matter e) all are true of the second law 5)For many enzymes the rate of product formation increases as the concentration of substrate increases. Eventually the rate of the reaction reaches a maximum, where further increases in the concentration of substrate have no effect. Why? A) At high concentration of substrate, all of the available enzyme molecules are bound to substrate molecules b)at high concentrations of substrate, the activation energy of the reaction increases c)at high concentrations of substrate the activation of energy of the reaction decreases d)the enzyme is no longer specific for substrate e) at high concentrations of substrate the reaction is endergonic 6) each of the following contains twelves carbon atoms. which of the arrangements demonstrates carbon atoms with the greatest entropy? a) twelve molecules of CO 2 b) one molecule C12 H22 O 11 c)two molecules of C6 H12 O6 d) four molecules of C3 H4 O3 E) It is impossible to determine

• Answer:

  1-A) the phospholipid bilayer, because of its non-polar tails and its polar heads repels most things trying to cross the barrier. 2-C) Enzymes to not provide any energy for a reaction, but they lower the activation energy needed for a reaction to occur by binding to the transition state (the high-energy state between reaction and products where bonds are being broken or formed) 3-E) In order, gravitational, chemical, elastic, and electrochemical potential energy. 4-C) All chemical reactions are not exergonic, spontaneous chemical reactions are exergonic, but by adding energy we can increase the organization of a system (endergonic reaction). 5-A) Eventually you do run out of available catalysts at any one time. They do have their limits 6-A) Because CO2 is a gas and it is a small molecule, these have the highest entropy (you can think of it as degrees of freedom if you'd like)