Q: Which equation correctly represents the overall chemical reaction for cellular respiration?

$$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} \rightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O} + \text{energy}$$

Q: Which equation correctly represents the overall chemical reaction for photosynthesis?

$$6\mathrm{CO_2$} + 12\mathrm{H_2O} + \text{light energy} \rightarrow \mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} + 6\mathrm{H_2O}$$

Question 1

Which of the following best describes substrate-level phosphorylation during cellular respiration?

Accepted Answer

ATP is produced directly by transferring a phosphate group from a substrate molecule to ADP.

Question 2

What is the main difference between oxidative phosphorylation and substrate-level phosphorylation?

Accepted Answer

Oxidative phosphorylation uses a proton gradient and ATP synthase, while substrate-level phosphorylation transfers a phosphate directly from a substrate to ADP.

Question 3

Is glycolysis oxygen dependent or independent, and why is this significant for cells in anoxic environments?

Accepted Answer

Glycolysis is oxygen independent, allowing cells to generate ATP even when oxygen is unavailable.

Question 4

Why is the electron transport chain (ETC) considered oxygen dependent?

Accepted Answer

Oxygen acts as the terminal electron acceptor, allowing electrons to flow through the chain and enabling ATP production.

Question 5

During the Krebs (citric acid) cycle, why is the process considered oxygen dependent even though O$$_2 is $$not directly used?

Accepted Answer

The cycle produces NADH and FADH$$_2$$, which must be oxidized by the electron transport chain that requires oxygen.

Question 6

If oxygen supply is cut off, what happens to the electron transport chain and ATP production?

Accepted Answer

The electron transport chain stops, NADH accumulates, and ATP production via oxidative phosphorylation ceases.

Question 7

In anoxic environments, some cells perform metabolism exclusively via fermentation. What is the main advantage of fermentation?

Accepted Answer

Fermentation allows regeneration of NAD$$^+$$, enabling glycolysis to continue producing ATP without oxygen.

Question 8

Which of the following is a product of lactic acid fermentation?

Accepted Answer

Lactic acid

Question 9

Alcohol fermentation is commonly found in which type of organism?

Accepted Answer

Yeast

Question 10

Which equation correctly represents the overall chemical reaction for cellular respiration?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} ightarrow 6\mathrm{CO_2$} + 6\mathrm{H_2O} + 	ext{energy}$$

Question 11

Which equation correctly represents the overall chemical reaction for photosynthesis?

Accepted Answer

$$6\mathrm{CO_2$} + 12\mathrm{H_2O} + 	ext{light energy} ightarrow \mathrm{C_6H_{12}O_6$} + 6\mathrm{O_2$} + 6\mathrm{H_2O}$$

Question 12

Which organelle is responsible for photosynthesis in eukaryotic cells?

Accepted Answer

Chloroplast

Question 13

What is the role of chlorophyll in photosynthesis?

Accepted Answer

It absorbs light energy to drive the synthesis of organic molecules.

Question 14

Which organisms are capable of photosynthesis?

Accepted Answer

Plants, cyanobacteria, and some algae

Question 15

What is the main global significance of photosynthesis?

Accepted Answer

It captures solar energy and converts atmospheric CO$$_2$$ into organic molecules, supporting most life on Earth.

Question 16

Which part of the chloroplast contains the green pigment chlorophyll?

Accepted Answer

Thylakoid membrane

Question 17

During the light reactions of photosynthesis, what is the primary function of water?

Accepted Answer

Water is split to provide electrons and protons, releasing O$$_2 as a $$byproduct.

Question 18

Which process in cellular respiration produces the most ATP per glucose molecule?

Accepted Answer

Oxidative phosphorylation

Question 19

Why do atmospheric CO$$_2$$ levels fluctuate seasonally, as observed at Mauna Loa Observatory?

Accepted Answer

Photosynthetic activity in northern hemisphere forests increases in spring and summer, lowering CO$$_2$$ levels, and decreases in fall and winter, raising CO$$_2$$ levels.

Cellular Respiration and Photosynthesis: Key Concepts and Pathways

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