Q: During the light-dependent reactions of oxygenic photosynthesis, what is the overall chemical equation for the process?

$$6\ \mathrm{CO}_2 + 12\ \mathrm{H}_2\mathrm{O} + \text{light energy} \rightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\ \mathrm{H}_2\mathrm{O} + 6\ \mathrm{O}_2$$

Question 1

Which of the following best describes the relationship between catabolic and anabolic pathways in cellular metabolism?

Accepted Answer

Catabolic pathways release energy by breaking down macromolecules, and this energy is used by anabolic pathways to build macromolecules from simple molecules.

Question 2

Which of the following statements about bacteriorhodopsin-based phototrophy is correct?

Accepted Answer

It is found in halophilic archaea and involves a single-protein, light-driven proton pump.

Question 3

In cyclic photophosphorylation, which of the following occurs?

Accepted Answer

Electrons return to chlorophyll after passing through the electron transport chain, and only ATP is produced.

Question 4

Which of the following is a key difference between Photosystem I (PSI) and Photosystem II (PSII) in bacterial photosynthesis?

Accepted Answer

PSI is involved in cyclic photophosphorylation and produces only ATP, while PSII can produce both ATP and NAD(P)H.

Question 5

During the light-dependent reactions of oxygenic photosynthesis, what is the overall chemical equation for the process?

Accepted Answer

$$6\ \mathrm{CO}_2 + 12\ \mathrm{H}_2\mathrm{O} + 	ext{light energy} ightarrow \mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6 + 6\ \mathrm{H}_2\mathrm{O} + 6\ \mathrm{O}_2$$

Question 6

Which of the following best describes the function of the Calvin-Benson cycle?

Accepted Answer

It uses ATP and NADPH to fix $$\mathrm{CO}_2$$ into organic sugars.

Question 7

Which of the following is a correct summary of the Z-pathway (oxygenic photolysis) in cyanobacteria and chloroplasts?

Accepted Answer

It absorbs eight photons, removes 4H+ and 4e- from 2H2O, produces O2, and forms 3 ATP and 2 NADPH per 2 H2O photolyzed.

Question 8

Which of the following statements about photophosphorylation and oxidative phosphorylation is correct?

Accepted Answer

Both processes use an electron transport chain to generate a proton gradient that drives ATP synthesis via ATP synthase.

Question 9

A bacterium that uses light as an energy source and organic compounds as a carbon source is best classified as which nutritional type?

Accepted Answer

Photoheterotroph

Question 10

Which of the following is an example of an amphibolic pathway?

Accepted Answer

Glycolysis, because it can function in both the breakdown of glucose and the synthesis of intermediates for biosynthesis.

Question 11

Which of the following best explains how amino acids are synthesized in bacteria?

Accepted Answer

Amino acids are synthesized from intermediates of carbohydrate metabolism, such as those from the Krebs cycle, pentose phosphate pathway, and Entner-Doudoroff pathway.

Question 12

Which of the following is a correct description of transamination in amino acid biosynthesis?

Accepted Answer

Transamination is the process by which an amino group is transferred from an amino acid to a keto acid, forming a new amino acid and a new keto acid.

Question 13

Which of the following statements about the biosynthesis of nucleotides is correct?

Accepted Answer

The pentose sugar in nucleotides is derived from the pentose phosphate pathway or Entner-Doudoroff pathway, and the nitrogenous bases are synthesized from amino acids such as glutamine and aspartic acid.

Question 14

A mutant cyanobacterium is unable to split water during photosynthesis. Which of the following would most likely be affected?

Accepted Answer

The production of O2 and the supply of electrons to the electron transport chain in the Z-pathway.

Question 15

Which of the following best summarizes energy production in cells?

Accepted Answer

Cells obtain energy by oxidizing molecules such as glucose, sulfur, or sunlight, transferring electrons through an electron transport chain to generate a proton gradient that drives ATP synthesis.

Question 16

Which of the following is a real-world example of a chemoheterotroph?

Accepted Answer

A human, which obtains both energy and carbon from organic compounds.

Question 17

Which of the following best describes the integration of metabolic pathways using peptidoglycan synthesis as an example?

Accepted Answer

Peptidoglycan synthesis uses intermediates from glycolysis and the pentose phosphate pathway, demonstrating how catabolic and anabolic pathways share common intermediates.

Question 18

Which of the following is a correct multi-step pathway for the biosynthesis of simple lipids in bacteria?

Accepted Answer

Dihydroxyacetone phosphate from glycolysis is converted to glycerol, and acetyl CoA from the Krebs cycle is used to synthesize fatty acids. Glycerol and fatty acids combine to form simple lipids.

Microbial Metabolism: Photosynthesis, Energy Production, and Metabolic Pathways

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