Phototrophy, Chemolithotrophy, & Biosynthesis (E2)

Question 1

Photoautotrophy combines the { } rxn (energy step) and { } rxn (carbon fixation).

Answer 1

1) Light
2) Dark

Question 2

Another name for the light reaction.

Answer 2

What is photophosphorylation?

Question 3

Another name for the dark reaction.

Answer 3

What is the Calvin cycle?

Question 4

This type of phototrophy releases oxygen.

Answer 4

What is oxygenic?

Question 5

This type of phototrophy is only seen in prokaryotes and doesn’t result in oxygen release.

Answer 5

What is anoxygenic/anaerobic?

Question 6

This type of phototrophy converts sun energy to ATP in non-photosynthetic prokaryotes but can’t use CO2 to make organic molecules.

Answer 6

What is Rhodopsin-based?

Question 7

What are the primary pigments for oxygenic and anoxygenic phototrophy, respectively.

Answer 7

Oxygenic - chlorophyll

Anoxygenic - bacteriochlorophyll

Question 8

Oxygenic phototrophy uses { } photosystem(s) while anoxygenic uses { }.

Answer 8

1) 2
2) 1

Question 9

What are the electron donors for oxygenic and anoxygenic phototrophy, respectively?

Answer 9

Oxygenic - H2O

Anoxygenic - H2, H2S, reduced iron

Question 10

This type of phosphorylation produces only ATP.

Answer 10

What is cyclic?

Question 11

This type of phosphorylation produces ATP, NADPH, and O2.

Answer 11

What is non-cyclic?

Question 12

What molecule is split as a source of electrons to make NADPH in oxygenic phototrophy?

Answer 12

Water

Question 13

Why is reverse electron flow considered energy-expensive?

Answer 13

It requires ATP

Question 14

Why is reverse electron flow important to anoxygenic phototrophy?

Answer 14

Generating reducing power

Question 15

What are the 3 requirements for biosynthesis?

Answer 15

1) Organic elements (HONC)
2) Reducing agents (NADPH)
3) Energy

Question 16

What can biosynthetic reaction intermediates be used for?

Answer 16

Precursor metabolites for other pathways

Question 17

What is the purpose of the Calvin cycle?

Answer 17

To consume energy (ATP, NADPH) to fix CO2

Question 18

What are the 3 steps of the Calvin cycle?

Answer 18

1) Carboxylation
2) Reduction
3) Regeneration of RuBP

Question 19

This organelle, present in some bacteria, increases the efficiency of light absorption.

Answer 19

What are thylakoids?

Question 20

What is the purpose of the carboxysome?

Answer 20

To store enzymes required for reducing CO2 into sugars

Question 21

Given that the Calvin cycle is a biosynthetic process, it can be said to be…

Answer 21

Anabolic

Question 22

Since archaea have no true photosystems, what pigment complex do they use to capture radiant energy via light-driven PMF?

Answer 22

Bacteriorhodopsin

Question 23

Given that the prefix “lith” in lithotrophy means stone, lithotrophy requires { } compounds to serve as electron donors and an energy source.

Answer 23

Inorganic

Question 24

Name 3 chemolithotrophic electron donor processes.

Answer 24

1) Sulfur & metal oxidation
2) Nitrogen oxidation
3) Hydrogenotrophy

Question 25

For what 2 reasons is chemolithoautotrophy very inefficient?

Answer 25

1) More energy spent on making reducing power than ATP
2) Many organics grow as heterotrophs if given organic carbon