Question 1

How are NADH and FADH₂similar?

Accepted Answer

NADH and FADH2 both contain high energy electrons, which are used in the electron transport chain to produce ATP indirectly. They do not directly produce ATP, are not used in glycolysis, do not contain high energy phosphates, and are in their reduced forms (not oxidized) when carrying electrons.

Question 2

Which answer best describes energy flow in biological systems?

Accepted Answer

Energy in biological systems often flows from glucose to G3P (glyceraldehyde 3-phosphate) during glycolysis, then to NADH as part of the electron transport chain, and finally to ATP, which is the main energy currency of the cell.

Question 3

If the inner membrane of the mitochondria were compromised in some way, what effect would this have on cellular respiration?

Accepted Answer

B

Question 4

At the end of cellular respiration, oxygen combines with electrons of a very low energy level. How are the specific properties of oxygen beneficial to the organism that uses it as a final electron acceptor?

Accepted Answer

Oxygen allows a maximum output of energy for ATP synthesis.

Question 5

What is the ultimate fate of the atoms in oxygen gas (O₂) in cellular respiration?

Accepted Answer

In cellular respiration, the oxygen gas (O2) atoms are ultimately incorporated into water (H2O) as a result of the electron transport chain and chemiosmosis, where oxygen acts as the final electron acceptor.

Question 6

During glycolysis, glucose molecules are broken down by breaking the carbon-hydrogen bonds that are present and forming carbon-oxygen bonds. In this process, glucose is ____.

Accepted Answer

Glycolysis involves the partial oxidation of glucose, where glucose is broken down into pyruvate, and in the process, some of its carbon-hydrogen bonds are broken and replaced with carbon-oxygen bonds, indicating oxidation. However, it is not completely oxidized; that occurs later in cellular respiration.

Question 7

Where would you expect to find proteins responsible for controlling the substances that enter and leave mitochondria?

Accepted Answer

The inner mitochondrial membrane contains proteins that control the passage of substances into and out of the mitochondria, as it is selectively permeable and contains transport proteins and channels.

Question 8

In the absence of ATP synthase, animal cells would not be able to ____.

Accepted Answer

ATP synthase is the enzyme that synthesizes ATP from ADP and inorganic phosphate. In the absence of ATP synthase, animal cells would not be able to produce ATP.

Question 9

What type of chemical reaction must occur for electrons to flow from one molecule to the next and supply the energy for metabolism?

Accepted Answer

Reduction/oxidation (redox) reactions involve the transfer of electrons from one molecule to another. This electron transfer is fundamental to the process of generating energy in biological systems, as it drives the flow of electrons through the electron transport chain, ultimately leading to ATP synthesis in cellular respiration and photosynthesis.

Question 10

What supplies the electrons for oxidative phosphorylation?

Accepted Answer

NADH and FADH2 are electron carriers that donate electrons to the electron transport chain, which is a crucial part of oxidative phosphorylation.

Question 11

In prokaryotes, ____ occur(s) in the cytosol.

Accepted Answer

Glycolysis, pyruvate oxidation, and the citric acid cycle all occur in the cytosol of prokaryotes.

Question 12

It has been thought that many diseases now associated with aging are related to malfunctioning mitochondria. Why are the mitochondria so important to all cells?

Accepted Answer

Mitochondria are known as the powerhouses of the cell because they produce energy in the form of ATP (adenosine triphosphate), which is essential for various cellular functions.

Question 13

Oxidative phosphorylation is the process by which ____.

Accepted Answer

Oxidative phosphorylation involves the use of a final electron acceptor (usually oxygen) to indirectly facilitate the production of ATP through the electron transport chain and ATP synthase.

Question 14

The initial step of glycolysis involves the ____ of glucose.

Accepted Answer

The initial step of glycolysis involves the phosphorylation of glucose, which is the addition of a phosphate group to glucose to form glucose-6-phosphate. This step is catalyzed by the enzyme hexokinase or glucokinase and requires ATP.

Question 15

The enzymes responsible for hydrolyzing glucose into glyceraldehyde-3-phosphate (G3P) are found in which part of the cell?

Accepted Answer

The enzymes responsible for hydrolyzing glucose into glyceraldehyde-3-phosphate (G3P), a step in glycolysis, are found in the cytosol of the cell.

Question 16

How does cellular respiration differ in prokaryotes and eukaryotes?

Accepted Answer

Eukaryotes perform cellular respiration reactions in mitochondria, while prokaryotes, lacking mitochondria, carry out these reactions across their plasma membrane.

Question 17

When individuals have mitochondrial disorders, why are the skeletal and heart muscles and the brain most often affected?

Accepted Answer

Skeletal and heart muscles and the brain are most often affected by mitochondrial disorders because these tissues have the highest energy needs. Mitochondria are responsible for producing the energy that cells need to function, so when there are problems with the mitochondria, tissues that require a lot of energy are more severely impacted.

Question 18

In the process of aerobic metabolism, carbon containing molecules are broken down and the energy from the electrons is used to ____.

Accepted Answer

In aerobic metabolism, the energy from electrons released during the breakdown of carbon-containing molecules is used to generate a proton gradient across a membrane. This proton gradient is then used to produce ATP through oxidative phosphorylation, providing energy for cellular processes.

Question 19

When a molecule is reduced, it ____.

Accepted Answer

When a molecule is reduced, it gains electrons. This is a fundamental principle of redox reactions in chemistry, where reduction refers to the gain of electrons.

Question 20

The final product of glycolysis is ____.

Accepted Answer

The final product of glycolysis is pyruvate. Glycolysis is a metabolic pathway that converts glucose into pyruvate, generating ATP and NADH in the process.

Quiz 7: Cellular Respiration: Harvesting Chemical Energy

How are NADH and FADH2similar?