Q: Which of the following equations correctly represents the overall process of cellular respiration?

$$\mathrm{C_6H_{12}O_6$} + \mathrm{6\ O_2$} \rightarrow \mathrm{6\ CO_2$} + \mathrm{6\ H_2O} + \text{Energy (ATP + Heat)}$$

Question 1

Which of the following best describes the role of oxygen in aerobic cellular respiration?

Accepted Answer

Oxygen acts as the final electron acceptor in the electron transport chain, becoming reduced to form water.

Question 2

A patient’s muscle cells are deprived of oxygen during intense exercise. Which process allows these cells to continue producing ATP, and what is the final electron acceptor?

Accepted Answer

Lactic acid fermentation; pyruvate is the final electron acceptor.

Question 3

Which of the following equations correctly represents the overall process of cellular respiration?

Accepted Answer

$$\mathrm{C_6H_{12}O_6$} + \mathrm{6\ O_2$} ightarrow \mathrm{6\ CO_2$} + \mathrm{6\ H_2O} + 	ext{Energy (ATP + Heat)}$$

Question 4

Which of the following statements about the electron transport chain (ETC) in mitochondria is correct?

Accepted Answer

Electrons from NADH and FADH$$_2$$ are transferred through a series of increasingly electronegative carriers, ultimately reducing oxygen to water.

Question 5

During which stage of cellular respiration is the majority of ATP produced, and by what mechanism?

Accepted Answer

Oxidative phosphorylation; ATP is produced by chemiosmosis as H$$^+$$ ions flow through ATP synthase.

Question 6

Which of the following best explains why fats yield more ATP per gram than carbohydrates during cellular respiration?

Accepted Answer

Fats have more C–H bonds, providing more electrons for oxidation in the electron transport chain.

Question 7

A plant is exposed to light, but its thylakoid membranes are damaged. Which process will be most directly affected?

Accepted Answer

The light reactions, including ATP and NADPH production, will be impaired.

Question 8

Which adaptation allows CAM plants to survive in hot, dry environments?

Accepted Answer

They open their stomata at night to fix CO$$_2$$, storing it for use during the day when stomata are closed.

Question 9

Which enzyme catalyzes the fixation of CO$$_2 to $$RuBP in the Calvin cycle, and what is a consequence if this enzyme binds O$$_2$$ instead?

Accepted Answer

RUBISCO; photorespiration occurs, wasting energy and releasing CO$$_2.$$

Question 10

Which of the following is a correct sequence of events in a G-protein coupled receptor (GPCR) signaling pathway?

Accepted Answer

Ligand binds receptor → G-protein exchanges GDP for GTP → G-protein activates adenylyl cyclase → cAMP is produced.

Question 11

A mutation causes a kinase in a phosphorylation cascade to be constitutively active (always on). What is a likely cellular consequence?

Accepted Answer

The signal transduction pathway will remain active, possibly leading to uncontrolled cell responses.

Question 12

Which of the following best describes the difference between paracrine and endocrine signaling?

Accepted Answer

Paracrine signaling acts on nearby cells using local regulators, while endocrine signaling uses hormones that travel through the bloodstream to distant cells.

Question 13

During which phase of mitosis do sister chromatids separate and move toward opposite poles of the cell, and what protein is cleaved to allow this separation?

Accepted Answer

Anaphase; cohesin proteins are cleaved.

Question 14

A researcher observes a cell with condensed chromosomes aligned at the metaphase plate, spindle fibers attached to kinetochores, and centrosomes at opposite poles. Which phase is this cell in?

Accepted Answer

Metaphase

Question 15

Which of the following statements about binary fission in bacteria is correct?

Accepted Answer

Binary fission does not involve mitosis; the bacterial chromosome is replicated starting at the origin of replication.

Question 16

Which checkpoint in the cell cycle is most critical for determining whether a cell will divide or enter a non-dividing state, and what is this non-dividing state called?

Accepted Answer

G1 checkpoint; the non-dividing state is called G0.

Question 17

A cancer cell line is observed to divide indefinitely, even when crowded and after DNA damage. Which features of normal cell cycle regulation are most likely lost in these cells?

Accepted Answer

Density-dependent inhibition and apoptosis.

Question 18

Which of the following best describes the role of second messengers in cell signaling?

Accepted Answer

They are small, non-protein molecules that help amplify the signal within the cell.

Question 19

Which of the following is a correct description of substrate-level phosphorylation?

Accepted Answer

ATP is formed directly by transferring a phosphate group from a substrate to ADP during glycolysis or the citric acid cycle.

Question 20

Which of the following is a direct input to the Calvin cycle, and what is the main sugar product that exits the cycle?

Accepted Answer

CO$$_2 is an $$input; G3P is the main sugar product.

Cellular Respiration, Photosynthesis, Cell Signaling, and the Cell Cycle: Exam II Study Guide

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