MIC 102 - MIDTERM 2 QUESTIONS & ANSWERS
Carbon fixation is a feeder pathway for - Answers -autotrophs
Why is carbon fixation considered to be an expensive pathway? - Answers -requires
lots of ATP, reducing power from NADPH, and complex series of reactions to convert
inorganic CO2 into organic molecules.
Which of the following best represents the inputs and outputs of the Calvin cycle in most
species?
a. 6 CO2 + 18 ATP + 12 NADPH --> 1 Glucose
b. 6 CO2 + 18 ATP + 12 NADPH --> 1 Fructose-6-phosphate
c. 6 CO2 + 12 ATP + 18 NADPH --> 1 Fructose-6-phosphate
d. 6 CO2 + 18 ATP + 12 NADH --> 1 Fructose-6-phosphate - Answers -b. 6 CO2 + 18
ATP + 12 NADPH --> 1 Fructose-6-phosphate
The Calvin cycle requires __ ATP, __ NADPH, and __ molecules of carbon dioxide to
synthesize one molecule of Fructose-6-phosphate. - Answers -18 ATP
12 NADPH
6 CO2
Carbon fixation must be _______________ in carboxysomes for increased efficiency -
Answers -sequestered (isolated)
What is the critical enzyme for carbon fixation? - Answers -RuBisCO
What is RuBisCO sensitive to? - Answers -oxygen
What is the primary function of RuBisCO in the Calvin cycle?
a. fixing CO2 into organic molecules
b. converting ATP to ADP
c. breaking down glucose for energy
d. facilitating oxygen exchange in chloroplasts - Answers -a. fixing CO2 into organic
molecules
Why is RuBisCO considered a slow and inefficient enzyme despite its key role in
photosynthesis?
a. it requires large amounts of ATP to function
b. it has a low affinity for carbon dioxide
c. it can react with oxygen, leading to photorespiration
,d. it functions only under high-light conditions - Answers -c. it can react with oxygen,
leading to photorespiration
What is the difference between photophosphorylation and oxidative phosphorylation? -
Answers -phosphorylation energy source comes from light
oxidative phosphorylation energy source comes from oxidation of some reduced
compound
What are the two types of anoxygenic photosynthesis? - Answers -1. cyclic (purple
bacteria)
2. non-cyclic (green bacteria)
What is the primary difference between oxygenic and anoxygenic photosynthesis?
a. Oxygenic photosynthesis produces oxygen, while anoxygenic photosynthesis does
not.
b. Oxygenic photosynthesis uses light energy, while anoxygenic photosynthesis does
not.
c. Oxygenic photosynthesis uses organic electron donors, while anoxygenic
photosynthesis uses water.
d. Anoxygenic photosynthesis produces glucose, while oxygenic photosynthesis does
not. - Answers -a. Oxygenic photosynthesis produces oxygen, while anoxygenic
photosynthesis does not.
Which statement best describes cyclic anoxygenic photosynthesis?
a. Electrons are passed along an electron transport chain and eventually return to the
original photosystem.
b. Electrons are passed along an electron transport chain and end up reducing NADP+
to NADPH.
c. Oxygen is produced as a byproduct.
d. Water is used as the electron donor. - Answers -a. Electrons are passed along an
electron transport chain and eventually return to the original photosystem.
---
In cyclic anoxygenic photosynthesis, electrons circulate in a closed loop, returning to the
same photosystem from which they originated. This process primarily generates ATP.
What is the key difference between cyclic and non-cyclic anoxygenic photosynthesis?
a. Cyclic photosynthesis does not produce oxygen, while non-cyclic photosynthesis
does.
b. Cyclic photosynthesis involves water as the electron donor, while non-cyclic
photosynthesis uses other electron donors.
, c. Cyclic photosynthesis results in ATP production, while non-cyclic photosynthesis can
also produce NADPH.
d. Cyclic photosynthesis occurs in plants, while non-cyclic photosynthesis occurs in
bacteria - Answers -c. Cyclic photosynthesis results in ATP production, while non-cyclic
photosynthesis can also produce NADPH.
---
In cyclic anoxygenic photosynthesis, electrons return to their source, leading primarily to
ATP production. Non-cyclic anoxygenic photosynthesis, on the other hand, can also
generate reducing power (like NADPH), as electrons do not return to the originating
photosystem.
Describe the cyclic cycle - Answers
-electrons get excited via light --> become better electron doner --> transfers to ETC -->
PMF (makes ATP) --> returns to terminal electron acceptor --> repeat
Describe the non-cyclic cycle - Answers
-reaction center 1 gets excited via light --> becomes better electron donor --> transfers
to ETC --> PMF --> different electron donor used to re-reduce ETC
Carbon fixation is a feeder pathway for - Answers -autotrophs
Why is carbon fixation considered to be an expensive pathway? - Answers -requires
lots of ATP, reducing power from NADPH, and complex series of reactions to convert
inorganic CO2 into organic molecules.
Which of the following best represents the inputs and outputs of the Calvin cycle in most
species?
a. 6 CO2 + 18 ATP + 12 NADPH --> 1 Glucose
b. 6 CO2 + 18 ATP + 12 NADPH --> 1 Fructose-6-phosphate
c. 6 CO2 + 12 ATP + 18 NADPH --> 1 Fructose-6-phosphate
d. 6 CO2 + 18 ATP + 12 NADH --> 1 Fructose-6-phosphate - Answers -b. 6 CO2 + 18
ATP + 12 NADPH --> 1 Fructose-6-phosphate
The Calvin cycle requires __ ATP, __ NADPH, and __ molecules of carbon dioxide to
synthesize one molecule of Fructose-6-phosphate. - Answers -18 ATP
12 NADPH
6 CO2
Carbon fixation must be _______________ in carboxysomes for increased efficiency -
Answers -sequestered (isolated)
What is the critical enzyme for carbon fixation? - Answers -RuBisCO
What is RuBisCO sensitive to? - Answers -oxygen
What is the primary function of RuBisCO in the Calvin cycle?
a. fixing CO2 into organic molecules
b. converting ATP to ADP
c. breaking down glucose for energy
d. facilitating oxygen exchange in chloroplasts - Answers -a. fixing CO2 into organic
molecules
Why is RuBisCO considered a slow and inefficient enzyme despite its key role in
photosynthesis?
a. it requires large amounts of ATP to function
b. it has a low affinity for carbon dioxide
c. it can react with oxygen, leading to photorespiration
,d. it functions only under high-light conditions - Answers -c. it can react with oxygen,
leading to photorespiration
What is the difference between photophosphorylation and oxidative phosphorylation? -
Answers -phosphorylation energy source comes from light
oxidative phosphorylation energy source comes from oxidation of some reduced
compound
What are the two types of anoxygenic photosynthesis? - Answers -1. cyclic (purple
bacteria)
2. non-cyclic (green bacteria)
What is the primary difference between oxygenic and anoxygenic photosynthesis?
a. Oxygenic photosynthesis produces oxygen, while anoxygenic photosynthesis does
not.
b. Oxygenic photosynthesis uses light energy, while anoxygenic photosynthesis does
not.
c. Oxygenic photosynthesis uses organic electron donors, while anoxygenic
photosynthesis uses water.
d. Anoxygenic photosynthesis produces glucose, while oxygenic photosynthesis does
not. - Answers -a. Oxygenic photosynthesis produces oxygen, while anoxygenic
photosynthesis does not.
Which statement best describes cyclic anoxygenic photosynthesis?
a. Electrons are passed along an electron transport chain and eventually return to the
original photosystem.
b. Electrons are passed along an electron transport chain and end up reducing NADP+
to NADPH.
c. Oxygen is produced as a byproduct.
d. Water is used as the electron donor. - Answers -a. Electrons are passed along an
electron transport chain and eventually return to the original photosystem.
---
In cyclic anoxygenic photosynthesis, electrons circulate in a closed loop, returning to the
same photosystem from which they originated. This process primarily generates ATP.
What is the key difference between cyclic and non-cyclic anoxygenic photosynthesis?
a. Cyclic photosynthesis does not produce oxygen, while non-cyclic photosynthesis
does.
b. Cyclic photosynthesis involves water as the electron donor, while non-cyclic
photosynthesis uses other electron donors.
, c. Cyclic photosynthesis results in ATP production, while non-cyclic photosynthesis can
also produce NADPH.
d. Cyclic photosynthesis occurs in plants, while non-cyclic photosynthesis occurs in
bacteria - Answers -c. Cyclic photosynthesis results in ATP production, while non-cyclic
photosynthesis can also produce NADPH.
---
In cyclic anoxygenic photosynthesis, electrons return to their source, leading primarily to
ATP production. Non-cyclic anoxygenic photosynthesis, on the other hand, can also
generate reducing power (like NADPH), as electrons do not return to the originating
photosystem.
Describe the cyclic cycle - Answers
-electrons get excited via light --> become better electron doner --> transfers to ETC -->
PMF (makes ATP) --> returns to terminal electron acceptor --> repeat
Describe the non-cyclic cycle - Answers
-reaction center 1 gets excited via light --> becomes better electron donor --> transfers
to ETC --> PMF --> different electron donor used to re-reduce ETC
