Question

biol 1100 - 01, - 04, - 07, - 10, - 13, - 16, cellular basis of life
midterm exam 2 (100 pts), fall, 2025

1. plants are generally considered: (a) autotrophs; (b) heterotrophs; (c) chemotrophs.
2. which part of an enzyme is critical for carrying out a chemical reaction? (a) active site; (b)

allosteric site; (c) the entire enzyme is important.

1. enzymes work by: (a) increasing the potential energy of the reactants; (b) increasing the kinetic

energy of the reactants; (c) lowering the activation energy of the reaction; (d) raising the
activation energy of the reaction.

1. in competitive inhibition, a chemical inhibitor competes with the substrate for the (a) distant

domain; (b) active site; (c) allosteric site; (d) none of the above.

1. in noncompetitive inhibition, a chemical inhibitor binds to the (a) distant domain; (b) active site;

(c) allosteric site; (d) none of the above.

1. there is no such thing as a system, either in nature or artificially (e.g., machines), that is 100%

efficient. this is because: (a) energy is always lost as heat; (b) the 2nd law of thermodynamics;
(c) the drive towards continuous disorder; (d) all of the above.

1. in atp, label the bond(s) in which potential energy (high - energy) is stored and then released

during a reaction. (a) bonds a and b; (b) bond a only; (c) bond b only; (d) bonds a and c;
(e) bonds c and d.

1. in a redox reaction, when one molecule gets reduced, the other gets: (a) also reduced; (b)

oxidized.

1. one way to make chemical reactions proceed is to heat them. however, this would kill the cell in

which the chemical reaction is supposed to occur. therefore, what has nature done to make sure
that such reactions proceed? (a) use enzymes; (b) use the potential energy of atp; (c) use the
kinetic energy of atp; (d) use the 2nd law of thermodynamics.

1. which of the following molecules is reduced? (a) nadh; (b) atp; (c) ch3coo - ; (d) fad +.

Explanation:

1. Plants produce their own food via photosynthesis, so they are autotrophs.
2. The active site of an enzyme binds to the substrate to carry out the reaction.
3. Enzymes lower the activation energy of a reaction, making it easier to occur.
4. In competitive inhibition, the inhibitor competes with the substrate for the active site.
5. In non - competitive inhibition, the inhibitor binds to the allosteric site.
6. All the options (A, B, C) are reasons why no system is 100% efficient. The second law of thermodynamics implies energy loss as heat and a drive towards disorder.
7. The high - energy bonds in ATP are the phosphate - phosphate bonds (Bonds A and B).
8. In a redox reaction, if one molecule is reduced (gains electrons), another is oxidized (loses electrons).
9. Enzymes are biological catalysts that speed up reactions without the need for excessive heat.
10. NADH is the reduced form of NAD+ (it has gained electrons). ATP is a high - energy molecule, \(CH_3COO^-\) is acetate, and \(FAD^+\) is the oxidized form.

Answer:

1. A. autotrophs
2. A. active site
3. C. lowering the activation energy of the reaction
4. B. active site
5. C. allosteric site
6. D. all of the above
7. A. Bonds A and B
8. B. oxidized
9. A. Use enzymes
10. A. NADH