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Chapter 6

Multiple Choice


1. Which of the following processes produces the most ATP molecules per glucose molecule consumed?
a. lactic acid fermentation
b. the Krebs cyscle
c. electron transport and chemiosmosis
d. alcoholic fermentation
e. glycolysis


2. When a poison such as cyanide blocks the electron transport chain, glycolysis and the Krebs cycle soon grind to a halt as well. Why do you think they stop? (Explain your answer)
a. They run out of ATP.
b. The buildup of unused oxygen interferes with glycolysis and the Krebs cycle.
c. They run out of NAD+ AND fad.
d. Electrons are no longer available from the electron transport chain
e. They run out of ADP.


3. A biochemist wanted to study how various substances were used and changed in cellular respiration. In one experiment, he allowed a mouse to breathe air containing a particular isotope of oxygen, O2* (a procedure harmless to the mouse). In the mouse, the "labeled" oxygen atoms, identified by* first showed up in 
a. ATP*
b. Glucose, C6H12O6* 
c. NADH*
d. Carbon dioxide, CO2*
e. Water, H2o*


4. In glycolysis——is oxidized and ——is reduced
a. NAD+……glucose 
b. Glucose……oxygen
c. ATP……ADP
d. Glucose……NAD+
e. ADP……ATP


5. Which of the following is the immediate source of the energy used to make most of the ATP in your cells?
a. the breakdown of ADP
b. the transfer of phosphate groups from glucose breakdown products to ADP
c. the movement of hydrogen ions through a membrane
d. the splitting of glucose into two molecules of pyruvic acid
e. the movement of electrons along the electron transport chain


6. Sports physiologists at an Olympic training center wanted to monitor athletes to determine at what point their muscles were functioning anaerobically. They could do this by checking for a buildup of 
a. ATP
b. Lactic acid
c. Carbon dioxide
d. ADP
e. Oxygen


Thinking as a Scientist


1. An average adult human requires 2200 kcal of energy per day. Suppose your diet provides an average of 2300 kcal per day. To avoid storing the extra calories as fat and gaining weight, you need additional exercise. How many hours per week would you have to walk to burn off the extra caloriex? Swim? Run? (See the table in Module 6.3)


2. As you may know from experience, it is possible for the body to convert excess carbohydrates in the diet (from too many sweets, for example) into fats, resulting in weight gain. It is not possible to convert a carbohydrate of into fats, resulting in weight gain. It is not possible to convert a carbohydrate or fat alone into protein; some input of protein from the diet is needed to assist in this conversion. What does the dietary protein contribute?


3. Your body makes NAD+ and FAD from two B vitamins, niacin and riboflavin. You need only tiny amounts of vitamins; the recommended dietary allowance for niacin is 20 mg daily and for riboflavin, 1.7mg. These amounts are thousands of times less than the amount of glucose your body needs each day to fuel its energy needs.How many NAD+ and FAD molecules are needed for the breakdown of each glucose molecule? Why do you think your daily requirement for these substances is so small?


4. In a detail of the Krebs cycle not shown in Figure 6.11B, succinic acid is converted to a compoun called fumairc acid, with the release of H+ ions. You are studying this reaction using a suspension of bean-cell mitochondria and a blue dye that loses its color as it takes up H+ ions. You know from previous experiments that the higher the concentration of succinic acid, the more rapid the decoloriztion of the blue dye. You set up reaction mixtures with mitochondria, dye, and three different concentrations of succinic acid (0.1 mg/L, 0.2mg/L, and 0.3mg/L). Which of the following graphs represents the results you would expect, and why?

 

Chapter 6 Answers 


Multiple Choice: 1.c 2.c (NAD+ and FAD, which are recycled by electron transport, are limited.) 3.e 4.d 5.c 6.b