Course Number: 211G A20
Course Name: Online – Natural History of Life
Instructor: Catherine Hartkorn
Individual/Partner Project – Biology Math Problems Assignment
Remember to write out your calculations and explanations for ALL problems.
Problem Set 3 – Problems on Enzymes and Cellular Respiration (3 problems):
6. Hydrogen peroxide is usually stored in a brown bottle away from sunlight because it
spontaneously (but slowly) decomposes into O2 and water. In the brown bottle, the free
energy of activation ∆G + = 18 kcal/mol. In the presence of a catalyst, the decomposition
is much faster. For each decrease of 1.36 kcal/mol in ∆G + , the rate of reaction is ten
In the presence of catalase, an enzyme found in the blood, ∆G + = 7 kcal/mol. In the
presence of the inorganic catalyst platinum, ∆G + = 13 kcal/mol.
a. How much faster is peroxide decomposition in the presence of a catalase?
b. How much faster is peroxide decomposition in the presence of platinum?
c. How many times faster is peroxide degradation under the influence of a catalase
than degradation under the influence of platinum?
7. You eat a candy bar that has 180 calories. This energy is converted during respiration to
ATP. The reaction ADP + Pi ATP requires 7.3 kcal/mol. One “dietary” calorie is
equal to 1000 “chemical” calories. Respiration is maximally about 39% efficient in
converting substrate calories to ATP calories.
a. Assuming that all of the energy in the candy actually gets to the respiratory site
in the cell, how many ATPs could your body make from this candy bar?
8. The first two stages in respiration are glycolysis and Kreb’s cycle. For each molecule of
10 NAD + molecules are reduced
2 FADs are reduced
4 ADPs are phosphorylated.
The free energy ∆G 0 ’ of the relevant “respiration reactions” is:
Reaction ∆G 0 ’ (kcal/mol)
NADH + H + + ½ O2 NAD
+ + H2O -51.7
FADH2 + ½ O2 FAD + H2O -43.4
ATP ADP + Pi -7.3
Glucose + 6 O2 6 CO2 + 6H2O -686
a. How much of the energy from one mole of glucose is converted into ATP during
the first two stages?
b. How much of the glucose energy is conserved in the reduced coenzymes NAD+
The third stage of respiration is oxidation phosphorylation.
c. A total of 32 ATPs per glucose molecule are made during oxidative
phosphorylation from the reduce coenzymes. How much of the glucose energy is
conserved in ATP at the end of ALL three stages?
d. What percentage of the total ATP energy is converted by the oxidative
phosphorylation of the reduced coenzymes?
e. What percentage of the glucose energy was lost was heat?