Question

(5) NADH and FADH₂ molecules are processed in the final sub pathway of cellular aerobic respiration. These molecules were described as carriers of _________________.

(A) energy                                                      (B) electrons    

(C) carbon units                                             (D) none of the above

(6) Adenosine triphosphate (A.T.P.) is

(A) energy rich compared with Adenosine diphosphate (A.D.P.)   

(B) energy poor compared with Adenosine diphosphate (A.D.P.)   

(C) not water soluble

(D) not dephosphorylated (that is, removal of a phosphate group) to liberate energy

(7) The pyruvate molecule that is produced in the first sub pathway of cellular aerobic respiration has three fates. In the specific case where a person is exercising vigorously and experiences muscle burn, which of the following molecules is produced?

(A) acetyl-CoA                                              (B) ethanol    

(C) lactic acid                                                (D) none of the above

(8) In your readings, you saw that photosynthesis as a classical example of anabolism. The pathway that is involved in breaking down water (H₂O) to produce molecular oxygen (O₂ is called

(A) the citric acid cycle (the Krebs cycle)     (B) the light dependent reactions    

(C) glycolysis                                               (D) the light independent reactions

(9) Which of the following statements are true with respect to the activity of enzymes?

(A)   they speed up chemical and biochemical reactions

(B)   they lower the “activation energy” of a reaction   

(C)   they are highly specific with respect to the molecules that can be bound to them

(D) all of the above

(10) When the molecule to be modified is bound within the enzyme’s active site, the resulting complex is called the

(A) enzyme-inhibitor complex  

(B) enzyme-activator complex

(C) enzyme-enzyme complex

(D) enzyme-substrate complex

(11) In your readings you saw that each step a metabolic pathway is carried out by an enzyme and that enzymes are highly dependent on their immediate environment to function. Which of the following factors affect enzyme activity?

(A) temperature                                             (B) acid-base balance (pH)    

(C) salt concentration (tonicity)                    (D) all of the above

Answer 1

5) NADH and FADH2 are reduced electron carriers, NAD+ and FAD+ are reduced by high energy electrons during glucose oxidation, these carry electrons to electron transport chain, so the answer is B) electrons.

6) ATP is adenosine triphosphate it has three phosphate groups and ADP is adenosine diphosphate, energy in the ATP is stored in anhydride bonds between phosphate groups in ATP there are two anhydride bonds and in ADP is only one anhydride bond between phosphate groups so ATP is rich in energy compared to ADP so the answer is

a) energy-rich compared with Adenosine diphosphate (A.D.P.)   

7) person is exercising vigorously and experiences muscle burn, the oxygen concentration in the muscle decreases, so energy is produced mainly via glycolysis. Pyruvate produced via glycolysis is converted to lactate by lactate dehydrogenase, during this reaction NADH is oxidised to NAD+, so that glycolysis can proceed, ( glycolysis requires NAD+ )

so the answer is (C) lactic acid  

8) during light reactions, electrons are excited from PSII and it finally ends up in NADPH, to replace electron in the PSII, water splitting complex associated with PSII splits water to O2, 2H+ and 2 electrons, so water splitting occurs in (B) the light dependent reactions