SBI4U                                                                         Metabolic Processes

 

Name                                                .                  2003 11 11

 

 

K                               25

I                              5

C                               6

A                            20

Bonus (K or A)                             4

 

Instructions:

1. Read over each question carefully. Attempt each question as no marks will be     

    deducted for incorrect responses.

2. Answer all questions on this test booklet. Show your work in pen (neatly).

3. The KICA allotment and mark breakdown is provided at the beginning of each section.

4. Each question is worth one mark unless otherwise specified.

5. Calculators may not be shared. You will forfeit this test if this rule is breached.

6. Do not write in symbols, abbreviations, or shorthand.

 

Initial here that you have read and understood the instructions           .

 

NB: For this test, assume that NADH_mit yields a maximum of 3 ATP and FADH₂ yields a maximum of 2 ATP.

 

 

1. Fill in the blanks. (8 )

 

a.         metabolism                    is the totality of an organism’s chemical processes.

b.         amino acid                    is a monomer of proteins.

c.         glycerol                         is the backbone of fats.

d.         starch                           is the energy storage molecule of plants.

e.         primary structure           is the amino acid sequence exhibited by polypeptides (give the order of folding).

f.          entropy                         is the scientific term for randomness or disorder.

g.         hydrolysis                      is the process of breaking down polymers into monomers.

h.         condensation/dehydration                       is the process of linking monomers together.

2. Fill in the blanks (9)

A. Non-cyclic electron flow during the photochemical reactions of photosynthesis

            generates ___NADPH______              ___, oxygen and ATP.

B. The first products of the Calvin Cycle (after CO₂ fixation) are two molecules of

            ______PGA_   ___(you may abbreviate).

C. Crassulacean acid (CAM) metabolism allows desert plants to close stomata during

            the_____day                ___ .

D. Photosystem  __I_(700)__ can participate in both cyclic and non-cyclic electron flow.

E. The enzyme rubisco  (you may give the shortened form) is probably the most abundant protein on the planet.

F. The shorter the wavelength of light, the           greater              its energy.

G. A product common to both cyclic and non-cyclic photophosphorylation is

            ATP                 .

H. The release of CO₂ in the presence of light without ATP synthesis is called    

photorespiration                         .

J. The breakdown of a water molecule by light energy is called    photolysis                      .

 

MULTIPLE CHOICE

 

3. If one acetyl CoA molecule is fed into the Krebs cycle, how many ATP molecules are made by substrate-level phosphorylation?

 

            A. one              B. two              C. eleven          D. twelve

4. If one acetyl CoA molecule is fed into the Krebs cycle, how many ATP molecules in total by substrate-level and oxidative phosphorylation?

 

            A. one              B. two              C. eleven          D. twelve

5. Which of the following summary reactions ultimately yields the most new ATP molecules under aerobic conditions? Assume the all electrons enter the electron transport chain.

 

A. 2 pyruvate ® 2 acetyl CoA

B. glucose ® 2 pyruvate

C. 2 G3P ® 2 pyruvate

D. 2 acetyl CoA ® carbon dioxide and water

E. 2 acetyl CoA ® 2 citrate

 

6. Ribulose is a 5 carbon sugar (monosaccharide) found in plants. Calculate the number of each type of molecule required to synthesize ONE molecule of ribulose or that may be formed as byproducts.  Assume C3 metabolism. (4)

 

Carbon dioxide   5      .

 

ATP   15      . 

 

NADPH   10      .

 

Electrons  20       .

 

Water    10       .

 

Oxygen     5       .

 

Photons   40      .

 

 

4. How would your answer in #3 differ if you had assumed C4 or CAM metabolism?

20 ATP would have been consumed instead of 15 (4ATP per carbon)

 

 

 

BONUS Write the balanced equation for the synthesis of one molecule of ribulose in the chloroplast (2)

 

5CO₂+ 10H₂O ® C₅H₁₀O₅ + 5O₂ + 5H₂0

 

 

 

1. How could you quantitatively observe whether a plant was using non-cyclic or cyclic photophosphorylation? Assume the technology exists. (2)

 

Since non-cyclic photophosphorylation evolves oxygen and cyclic does not, you could measure the oxygen output during the day. 

OR you could use radioactive water and see if the oxygen coming off the plant is radioactive.

 

 

2. In a working muscle, what would convince you beyond any doubt that pyruvate was not entering the mitochondrion?

 

If no carbon dioxide is being evolved, then pyruvate is not entering the mitochondrion.

 

 

3.  Choose EITHER photosynthesis OR cellular respiration. Prove that this process is a redox reaction. Be certain to indicate which molecule is being reduced and which is being oxidized(2)

 

P/S 6CO₂+ 12H₂O ® C₆H₁₂O₆ + 6O₂ + 6H₂0

carbon dioxide is reduced (accepts electrons) while water is oxidized (loses electrons)

 

OR

CR

C₆H₁₂O₆ + 6O₂ ®6CO₂+ 6H₂O  

glucose is oxidized (loses electrons) while oxygen is reduced (gains electrons)

 

 

 

 

 

 

1. State clearly and completely the First and Second Laws of Thermodynamics (2).

 

First law- Energy can be neither created nor destroyed only transferred or transformed

Second law- Every energy transfer or transformation increases the entropy of the universe

 

2. COMPARE the maximum ATP yield between an 18C saturated fatty acid AND 3 molecules of glucose. Indicate the starting point, sequence of reactions, all electron carriers, and type of phosphorylation. You may create a table to answer this question. (4)

 

legend SLP = substrate-level phosphorylation

OP = oxidative phosphorylation

 

18 C fatty acid                                                       3 glucose molecules (18C)

starts as 9 Acetyl CoA                                                              starts as glucose entering glycolysis                               

Krebs cycle 9 times                                                                   glycolysis, conversion of pyruvate, Krebs cycle (3 times)

9 ATP (SLP)                                                                            6 NADH (cytoplasmic) 24 NADH (mitochondrial) 6 FADH₂ as electron carriers

99 ATP (OP)                                                                            12 ATP (SLP)

27 NADH and 9 FADH₂ as electron carriers                              96 ATP (OP)

MAXIMUM ATP = 108                                                            MAXIMUM ATP 108                         

 

 

 

 

1. The diagram below represents an experiment with isolated chloroplasts.  The chloroplasts were first made acidic by soaking them in a solution at pH 4. After the thylakoid space reached pH 4, the chloroplasts were transferred to a basic solution of pH 8. This solution also contained ADP and inorganic phosphate.  The chloroplasts then made ATP in the dark.  Explain this result (3)

The chloroplasts carry a proton-motive force as protons from the acidic solution enter the thylakoid space. When the chloroplasts enter the basic solution

the protons diffuse down their concentration gradient into the solution. As the protons pass through the ATP synthase in the thylakoid membrane,

ATP is synthesized from the ADP and inorganic phosphate also present in the solution.

(Light is not necessary since a proton gradient has been artificially established)

 

 

2.  Of the following, a cell without enzymes would be most like

 

        A. an airport without air traffic controllers to route all the planes

        B .exploring a dark cave without a flashlight to see the way

        C. a college dormitory without a cafeteria for student dining

        D. an automobile factory without parts to assemble into cars

 

3. Of the basic processes of photosynthesis (11)

            A. cyclic photophosphorylation   B. non-cyclic photophosphorylation

            C. both light reactions    D. Calvin cycle             E. both light reactions and Calvin cycle

 

which process (or combination) involves

 

     D    utilization of CO₂                                   D    occurrence in the stroma of chloroplast

     E     redox reactions                               B     splitting of water

     C     light energized electrons                   C    production of ATP

     B     production of NADPH                    D    synthesis of G3P

     B     production of O₂                                      D   the utilization of NADPH

     A    chlorophyll as initial electron donor and final electron acceptor

 

4. What is the advantage of the light reactions producing ATP and NADPH on the stroma side of the thylakoid membrane?

The enzymes for the Calvin cycle are located in the stroma where the ATP and NADPH will be consumed.

 

5. CHOOSE A or B. (4)

A. Explain why a poison that inhibits an enzyme in the Calvin cycle will also inhibit the light reactions?

B. Explain why a poison that prevents oxygen from picking up electrons at the end of the electron transport chain will also prevent pyruvate from entering the mitochondrion.

A. If the Calvin cycle cannot run to completion if one step is inhibited, NADP+ and ADP + Pi cannot be returned (recycled/regenerated )to the light reactions. If electrons are not taken from the cycle, NADPH cannot be made so the chloroplast is limited to cyclic electron flow. But if there’s no ADP and Pi, no ATP will be made.

OR

B. If electrons can’t be siphoned off the electron transport chain, electron carriers cannot donate electrons to the chain. If NADH from glycolysis cannot

give up its electrons to the mitochondrion, then it must give them to pyruvate in the process of fermentation. Pyruvate cannot enter the mitochondrion during fermentation

 

 

BONUS (2) What do ‘B’ and ‘D’ represent in the diagram below?

B represents the activation energy

D represents the overall energy change (DG) of the reaction