Q: What is the overall stoichiometry for the Calvin cycle in terms of CO$$_2$$ fixation?

$$6 \text{CO}_2 + 12 \text{NADPH} + 18 \text{ATP} \rightarrow C_6H_{12}O_6$(P) + 12 \text{NADP}^+ + 18 \text{ADP} + 17 \text{P}_i$$

Question 1

Which of the following best describes a photoautotroph?

Accepted Answer

An organism that uses light energy to generate ATP and fixes carbon dioxide into organic compounds.

Question 2

Which pigment is most directly responsible for capturing light energy in oxygenic photosynthesis?

Accepted Answer

Chlorophyll a

Question 3

What is the main difference between oxygenic and anoxygenic photosynthesis?

Accepted Answer

Oxygenic photosynthesis generates oxygen as a byproduct, while anoxygenic does not.

Question 4

Which of the following is a key enzyme in the Calvin cycle?

Accepted Answer

Ribulose bisphosphate carboxylase

Question 5

Which process is responsible for the oxygenation of Earth's atmosphere, enabling aerobic respiration?

Accepted Answer

Oxygenic photosynthesis by cyanobacteria

Question 6

Which of the following statements about fermentation is correct?

Accepted Answer

Fermentation generates ATP by substrate-level phosphorylation.

Question 7

In the absence of oxygen, which process allows some bacteria to use nitrate as a terminal electron acceptor?

Accepted Answer

Anaerobic respiration

Question 8

Which of the following best describes the role of carotenoids in phototrophic organisms?

Accepted Answer

They serve as accessory pigments, protecting cells from photooxidative damage.

Question 9

Which pathway is used by green sulfur bacteria for carbon fixation?

Accepted Answer

The reverse citric acid cycle

Question 10

What is the overall stoichiometry for the Calvin cycle in terms of CO$$_2$$ fixation?

Accepted Answer

$$6 	ext{CO}_2 + 12 	ext{NADPH} + 18 	ext{ATP} ightarrow C_6H_{12}O_6$(P) + 12 	ext{NADP}^+ + 18 	ext{ADP} + 17 	ext{P}_i$$

Question 11

Which of the following is true about nitrogen fixation?

Accepted Answer

It requires the enzyme nitrogenase and a significant input of ATP.

Question 12

Which of the following best explains why fermentations yield less ATP than respirations?

Accepted Answer

Fermentations do not utilize an ion motive force for ATP generation.

Question 13

Which of the following is a correct description of the Z scheme in oxygenic photosynthesis?

Accepted Answer

It refers to the interaction between photosystem I and photosystem II to generate both ATP and NADPH.

Question 14

Which of the following is NOT a requirement for the Calvin cycle?

Accepted Answer

Ferredoxin

Question 15

A bacterium is found to use light as an energy source, organic compounds as an electron donor, and organic compounds as a carbon source. What is its nutritional type?

Accepted Answer

Photoorganoheterotroph

Question 16

Which of the following is a common electron acceptor in anaerobic respiration?

Accepted Answer

NO$$_3^-$$

Question 17

Which of the following statements about the reverse citric acid cycle is correct?

Accepted Answer

It is a pathway of CO$$_2$$ fixation used by green sulfur bacteria.

Question 18

Which of the following best describes the role of water in oxygenic photosynthesis?

Accepted Answer

It is split to provide electrons, resulting in the evolution of oxygen.

Question 19

Which of the following is a distinguishing feature of chemolithoautotrophs?

Accepted Answer

They use inorganic compounds as electron donors and CO$$_2 as a $$carbon source.

Metabolic Diversity in Microorganisms: Phototrophy, Autotrophy, Respiration, and Fermentation

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