BIO 156 - Chapter 6 (Mastering Biology)

Which of the following best describes the electron transport chain? A. Hydrogens are added to CO2 to make an energy-rich compound. B. Electrons pass from one carrier to another, releasing a little energy at each step. C. Electrons are pumped across a membrane by active transport. D. Acetyl CoA is fully oxidized to CO2.

B. Electrons pass from one carrier to another, releasing a little energy at each step.

Which of the following statements regarding glycolysis is FALSE? A. Glycolysis does not require compartmentalization by internal membranes. B. Glycolysis evolved in an oxygen-rich environment. C. Glycolysis is the most widespread metabolic pathway found in Earth's life. D. Glycolysis plays a role in both fermentation and respiration.

B. Glycolysis evolved in an oxygen-rich environment.

The transfer of ______________ from one molecule to another is an oxidation-reduction reaction, or redox reaction.

Electrons

For each glucose that enters glycolysis, _____ NADH enter the electron transport chain.

10 For each glucose molecule that enters glycolosis, a total of 10 NADH are produced -- 2 are produced in glycolysis, 2 are produced in acetyl CoA production, and 6 are produced in the citric acid cycle.

In glycolysis there is a net gain of _____ ATP.

2

In glycolysis, what starts the process of glucose breakdown?

ATP

The energy released from the redox reactions in the electron transport chain is used by the cell to make ______.

ATP

Which of these is NOT a product of the citric acid cycle (also called the Krebs cycle)?

acetyl CoA

Which of these enters the citric acid cycle (also called the Krebs cycle)?

acetyl CoA Acetyl CoA is a reactant in the citric acid cycle (also called the Krebs cycle).

Each turn of the citric acid cycle generates one ATP and ___ additional energy-rich molecules: __________.

four; 3 NADH and 1 FADH2 The citric acid cycle generates 3 molecules of NADH and 1 molecule of FADH2. These molecules carry high energy electrons that will be delivered to the electron transport chain.

The proximate (immediate) source of energy for oxidative phosphorylation is _____.

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient

In muscle cells, fermentation produces _____.

lactate and NAD+

Sports physiologists at an Olympic training center want to monitor athletes to determine at what point their muscles begin to function anaerobically. They could do this by checking for a buildup of _____.

lactic acid

NADH delivers electrons to an electron transport chain, which passes the electrons through carrier molecules in a series of redox reactions to the final electron acceptor, _______________.

oxygen

During electron transport, energy from _____ is used to pump hydrogen ions into the _____.

NADH and FADH2 ... intermembrane space The energy released as electrons, which have been donated by NADH and FADH2, is passed along the electron transport chain and used to pump hydrogen ions into the intermembrane space.

In cellular respiration, glucose becomes ___________ to carbon dioxide (CO2) as it loses electrons (in hydrogen atoms).

Oxidized

In eukaryotes, most of the high-energy electrons released from glucose by cellular respiration __________.

reduce NAD+ to NADH, which then delivers them to the electron transport chain Most of the high-energy electrons released from the glucose are picked up by NAD+ and sent through the electron transport chain.

A gram of fat oxidized by cellular respiration produces approximately __________ as much ATP as a gram of carbohydrate.

twice

In cellular respiration, organic molecules become oxidized as _________ picks up electrons and H+ and becomes reduced to NADH.

NAD+

Which of these is NOT a product of glycolysis?

FADH2

In cellular respiration, most ATP molecules are produced by _____.

oxidative phosphorylation

A chemist has discovered a drug that blocks phosphoglucoisomerase, an enzyme that catalyzes the second reaction in glycolysis. He wants to use the drug to treat people with bacterial infections. However, he can't do this because _____.

human cells also perform glycolysis; the drug might also poison them

We inhale O2 and we exhale CO2. Carbon dioxide is produced __________.

in the reaction that creates acetyl CoA (coenzyme A) from pyruvate Carbon dioxide is produced in the transition between glycolysis and the citric acid cycle when the three-carbon pyruvate is cleaved to a two-carbon acetyl molecule with the remaining carbon of pyruvate released as carbon dioxide. Carbon dioxide is also produced in the citric acid cycle itself.

In glycolysis, ATP molecules are produced by _______________________.

substrate-level phosphorylation

In the citric acid cycle (also called the Krebs cycle), ATP molecules are produced by _____.

substrate-level phosphorylation

How many NADH are produced by glycolysis?

2

Bacteria have no membrane-enclosed organelles. However, some still generate ATP through cellular respiration. Where might the electron transport chain be found in these organisms?

Plasma Membrane The electron transport chain requires a membrane that will act as a barrier to hydrogen ions that are being pumped across this space. The only membrane in a bacterial cell is the plasma membrane. Note that the inner membrane of a mitochondrion is a bacterial membrane obtained by the eukaryote through endosymbiosis.

In cellular respiration, oxygen becomes _________________ to water (H2O) as it gains electrons (in hydrogen atoms) that came from glucose.

Reduced

Through respiration, humans breathe in O2 and breathe out CO2. However, what would happen if we did not breathe in O2?

We would not make enough ATP to meet our energy requirements

In nutrient-rich environments (like your mouth), bacteria can use the provided amino acids to synthesize their proteins. However, should the environmental conditions change and become nutrient-poor, bacteria would need to synthesize their amino acids. They can do this using __________.

citric acid cycle intermediates

A single glucose molecule produces about 38 molecules of ATP through the process of cellular respiration. However, this only represents approximately 34% of the chemical energy present in this molecule. The rest of the energy from glucose is __________.

converted to heat

In the equation shown below, during cellular respiration __________ is oxidized and __________ is reduced.

glucose ... oxygen In cellular respiration, electrons and hydrogen are removed from glucose and added to oxygen.

A scientist wants to study the enzymes of the citric acid cycle in eukaryotic cells. What part of the cell would she use as a source of these enzymes?

mitochondrial matrix The water-soluble citric acid cycle intermediates and enzymes of a eukaryotic cell are found in the mitochondrial matrix, where the newly synthesized NADH and FADH2 diffuse to proteins of the electron transport chain held within the inner mitochondrial membrane. The matrix corresponds to the cytoplasm of the bacterium from which mitochondria are descended.

Some human cells, such as nerve cells, are restricted to aerobic respiration to recycle NADH and FADH2. If these cells are deprived of oxygen, then __________.

oxidative phosphorylation would come to a halt because there wouldn't be any oxygen to "pull" the electrons down the transport chain

The final electron acceptor of cellular respiration is _____.

oxygen

Most NADH molecules generated during cellular respiration are produced during __________.

the citric acid cycle There are 6 NADH molecules produced by the citric acid cycle per molecule of glucose. Two molecules of FADH2 are also produced by this cycle, which makes it a big source of high energy electron carriers.