1. their difference in size
2. their mode of nutrition
3. their difference in metabolic heat production
4. their mode of ATP production

1. the cytosol
2. the mitochondria
3. the plasma membrane
4. the nucleus

1. aerobic respiration
2. the citric acid cycle
3. oxidative phosphorylation
4. glycolysis

1. Glycolysis is the primitive pathway as it is found in all three domains. It also occurs in anaerobic conditions and in the cytosol.
2. This pathway occurs in the cytosol, is found in all animals and plants, and does not require oxygen.
3. Glycolysis takes place in anaerobic conditions, can metabolize cholesterol and fatty acids, and occurs even in methanogens.
4. This pathway only occurs in the mitochondria. It is highly flexible because it is found in almost all organisms.

1. the inner mitochondrial membrane
2. the mitochondrial matrix
3. a eukaryotic plasma membrane
4. the cytosol

What would be the most direct result of blocking Structure Z in the graphic?

Figure 7.23

1. Cytochrome c would not pass electrons from complex III to complex IV.
2. Ubiquinone would not pass electrons from complex III to complex IV.
3. NADH would not be converted to NAD⁺, and the electron transport chain would stop.
4. No protons would be pumped across the membrane.

Where do the electrons moving along the membrane in the figure come from, and where do the electrons end up?

Figure 7.24

1. The electrons are released by NADH and FADH₂ and finally accepted by oxygen to form water.
2. The electrons are given off by water and finally accepted by NAD⁺ and FAD⁺ to produce the energy currencies NADH and FADH₂.
3. The electrons are emitted by ubiquinone that are, in turn, transferred from complex I to complex II. Water finally accepts the electrons.
4. The electrons are given out by NADH and FADH₂ and are, in turn, finally accepted by H₂O.

Glucose catabolism pathways are sequential and lead to the production of energy. What is the correct order of the pathways for the breakdown of a molecule of glucose as shown in the formula

C₆H₁₂O₆ + O₂ → CO₂ + H₂O + energy?

1. oxidative phosphorylation → citric acid cycle → oxidation of pyruvate → glycolysis
2. the oxidation of pyruvate → citric acid cycle → glycolysis → oxidative phosphorylation
3. glycolysis → oxidation of pyruvate → citric acid cycle → oxidative phosphorylation
4. citric acid cycle → glycolysis → oxidative phosphorylation → oxidation of pyruvate

1. During cold periods, pond-dwelling animals can increase the number of unsaturated fatty acids in their cell membranes while some plants make antifreeze proteins to prevent ice crystal formation in their tissues.
2. Bacteria lack introns while many eukaryotic genes contain many of these intervening sequences.
3. Carnivores have more teeth that are specialized for ripping food while herbivores have more teeth specialized for grinding food.
4. Plants generally use starch molecules for storage while animals use glycogen and fats for storage.

1. Glycolysis produces pyruvate, which is converted to acetyl-CoA and enters the citric acid cycle. This cycle produces $\text{NADH}$ and ${\text{FADH}}_2$, which donate electrons to the electron transport chain to pump protons and produce $\text{ATP}$ through chemiosmosis. Production of $\text{ATP}$ using an electron transport chain and chemiosmosis is called oxidative phosphorylation.
2. The citric acid produces pyruvate, which converts to glucose to enter glycolysis. This pathway produces $\text{NADH}$ and ${\text{FADH}}_2$, which enter oxidative phosphorylation to produce $\text{ATP}$ through chemiosmosis.
3. Citric acid produces $\text{NADH}$ and ${\text{FADH}}_2$, which undergo oxidative phosphorylation. This produces $\text{ATP}$ by pumping protons through chemiosmosis. The $\text{ATP}$ produced is utilized in large amount in the process of glycolysis.
4. Glycolysis produces pyruvate, which directly enters the citric acid cycle. This cycle produces the energy currency that undergoes the electron transport chain to produce water and ATP.