Unit 10 Target 3: Cellular Respiration Quiz

Explanation
The correct answer is Pyruvic acid (pyruvate) and NADH. This is because the aerobic pathway of cellular respiration requires pyruvic acid (pyruvate) to enter the mitochondria and undergo further reactions, while the anaerobic pathway requires NADH to be converted back into NAD+ in order to continue the process of glycolysis. ATP is produced in both pathways, but it is not a requirement for glycolysis to occur.

Explanation
During alcoholic fermentation, glucose is split into three pyruvate molecules. This process does not require oxygen and occurs in the absence of it. One of the key steps in this process is the regeneration of NAD+. NAD+ is an important molecule in glycolysis, and its regeneration allows the process to continue. Without the regeneration of NAD+, glycolysis would come to a halt, and the production of ATP would cease. Therefore, the regeneration of NAD+ is crucial for the continuation of glycolysis during alcoholic fermentation.

Explanation
Fermentation and glycolysis are anaerobic processes that occur in the cytoplasm of the cell. Fermentation is a metabolic process that converts sugars into acids, gases, or alcohol, without the use of oxygen. Glycolysis is the initial step in cellular respiration, where glucose is broken down into pyruvate, also occurring in the absence of oxygen. Both processes take place in the cytoplasm to produce energy in the form of ATP.

Explanation
The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondria of cells. It is an important part of cellular respiration, which is the process by which cells produce energy. The Krebs cycle starts with pyruvic acid, which is a product of glycolysis, the first step of cellular respiration. During the Krebs cycle, pyruvic acid is converted into carbon dioxide, releasing energy in the process. This energy is used to produce ATP, the main source of energy for cells. Therefore, the correct answer is that the Krebs cycle starts with pyruvic acid and yields carbon dioxide.

Explanation
Lactic acid fermentation occurs in muscle cells. This is because during intense exercise, when oxygen supply is limited, muscle cells switch to anaerobic respiration to produce energy. In this process, glucose is broken down into lactic acid, which accumulates in the muscles and leads to fatigue and soreness.

Explanation
Photosynthesis and cellular respiration are almost opposite processes because photosynthesis removes carbon dioxide from the atmosphere, while cellular respiration puts it back. During photosynthesis, plants use sunlight to convert carbon dioxide and water into glucose and oxygen. This process helps to reduce the amount of carbon dioxide in the atmosphere. On the other hand, during cellular respiration, organisms break down glucose and oxygen to produce carbon dioxide, water, and energy. This process releases carbon dioxide back into the atmosphere. Therefore, option B is the correct answer as it accurately describes the opposite effects of photosynthesis and cellular respiration on the carbon dioxide levels in the atmosphere.

Explanation
The energy of the electrons passing along the electron transport chain is used to make ATP.

Explanation
The process that generates the most ATP produced during cellular respiration is the Electron Transport Chain (ETC). The ETC is the final stage of cellular respiration and occurs in the inner membrane of the mitochondria. It involves the transfer of electrons through a series of protein complexes, creating a proton gradient across the membrane. This gradient drives the synthesis of ATP by ATP synthase. Glycolysis and the Krebs cycle also produce ATP, but the ETC generates the most ATP out of all the processes involved in cellular respiration. Fermentation does not produce ATP through the same mechanisms as the other processes mentioned.

Explanation
NADH and FADH2 pass high-energy electrons into the electron transport chain. These molecules are produced during the citric acid cycle (also known as the Krebs cycle) in cellular respiration. NADH and FADH2 carry the high-energy electrons to the electron transport chain, where they undergo a series of redox reactions, ultimately leading to the production of ATP. Acetyl-CoA is an intermediate molecule in the citric acid cycle, while citric acid is the first molecule in the cycle. ATP and ADP are not directly involved in passing high-energy electrons into the electron transport chain.

Explanation
The equation represents cellular respiration, which is the process by which cells break down glucose and convert it into energy in the form of ATP. This process occurs in the mitochondria of the cell. Therefore, the correct answer is C) mitochondria.

Explanation
Cellular respiration occurs in all eukaryotic cells. Eukaryotic cells are a type of cell that have a nucleus and other membrane-bound organelles. This includes cells in plants, animals, fungi, and protists. Cellular respiration is the process by which cells break down glucose and other organic molecules to produce energy in the form of ATP. Therefore, it occurs in all eukaryotic cells, not just in plant cells or animal cells.

Explanation
At the end of the electron transport chain, the electrons combine with oxygen and protons to form water. This is known as the final step of cellular respiration, where oxygen acts as the final electron acceptor and combines with electrons and protons to produce water. This process occurs in the inner membrane of the mitochondria. Option A correctly states this process without any ambiguity.

Explanation
The correct sequence of events in aerobic cellular respiration is glycolysis, followed by the Krebs cycle, and then the electron transport chain. Glycolysis is the initial step in which glucose is broken down into pyruvate. The pyruvate then enters the Krebs cycle, where it is further broken down and produces energy-rich molecules. Finally, the energy-rich molecules are used in the electron transport chain to generate ATP, the main energy currency of the cell. Therefore, option C, glycolysis > Krebs cycle > electron transport, is the correct sequence.

Explanation
During the Krebs cycle, only 2 ATP molecules are produced, not 4 ATP molecules. The Krebs cycle is the second stage of aerobic cellular respiration and occurs in the mitochondria. It involves a series of chemical reactions that break down acetyl-CoA molecules, releasing energy in the form of ATP, NADH, and FADH2. The net gain of ATP molecules during the Krebs cycle is 2, not 4.

Explanation
The Krebs cycle takes place in the matrix, which is the innermost compartment of the mitochondria. This is where the majority of the chemical reactions of the Krebs cycle occur. Option C states that the Krebs cycle takes place in area 4 only, which refers to the matrix. Therefore, option C is the correct answer.

Explanation
Glycolysis is the process by which glucose is broken down into pyruvic acid (pyruvate). This is true because glycolysis is the first step in cellular respiration and occurs in the cytoplasm of the cell. During glycolysis, glucose is converted into two molecules of pyruvate, producing a small amount of ATP and NADH. Therefore, option C is the correct answer.

Explanation
Pathway C occurs in the presence of oxygen. This is because pathway C produces a large amount of ATP (36 ATP) through aerobic respiration, which requires oxygen. Pathway A and B, on the other hand, produce a smaller amount of ATP (2 ATP) through anaerobic respiration, which does not require oxygen. Therefore, only pathway C occurs in the presence of oxygen.