1.
Where does glycolysis take place?
Correct Answer
A. Cytoplasm
Explanation
Glycolysis is the metabolic pathway that breaks down glucose into pyruvate. It is the first step in cellular respiration and occurs in the cytoplasm of the cell. The cytoplasm is the fluid-filled region between the cell membrane and the nucleus, where many cellular processes take place. Therefore, glycolysis takes place in the cytoplasm.
2.
Which of the following statements best describes cellular respiration?
Correct Answer
C. Carbon-based molecules from food and oxygen are used to make ATP.
Explanation
Cellular respiration is the process by which cells convert carbon-based molecules from food and oxygen into ATP, which is the main source of energy for cellular activities. This process occurs in the mitochondria of cells and involves a series of chemical reactions that break down glucose and other organic molecules to release energy in the form of ATP. The answer option correctly describes this process by stating that carbon-based molecules from food and oxygen are used to make ATP.
3.
Which of the following are end products of glycolysis?
Correct Answer
D. Pyruvate, NADH, and ATP
Explanation
Glycolysis is the process of breaking down glucose into pyruvate. NADH and ATP are also produced during glycolysis. Therefore, the correct answer is pyruvate, NADH, and ATP.
4.
What is the main function of the Krebs cycle?
Correct Answer
C. Producing molecules that carry high-energy electrons to the electron transport chain
Explanation
The Krebs cycle, also known as the citric acid cycle, is a series of chemical reactions that occur in the mitochondria of cells. Its main function is to produce molecules that carry high-energy electrons to the electron transport chain. These high-energy electrons are generated through the breakdown of pyruvate molecules, which are derived from glucose metabolism. The Krebs cycle produces molecules such as NADH and FADH2, which carry these high-energy electrons to the electron transport chain, where they are used to generate ATP, the energy currency of the cell. Therefore, the correct answer is "producing molecules that carry high-energy electrons to the electron transport chain."
5.
In the electron transport chain, energy from the Krebs cycle is used to pump hydrogen ions
Correct Answer
A. Across the inner mitochondrial membrane.
Explanation
The electron transport chain is a series of protein complexes located in the inner mitochondrial membrane. It plays a crucial role in oxidative phosphorylation, the final step of cellular respiration. During the Krebs cycle, high-energy electrons are produced and carried by electron carriers to the electron transport chain. As these electrons pass through the protein complexes, they release energy, which is used to pump hydrogen ions across the inner mitochondrial membrane. This creates a concentration gradient, which is essential for ATP synthesis and the generation of cellular energy. Therefore, the correct answer is that energy from the Krebs cycle is used to pump hydrogen ions across the inner mitochondrial membrane.
6.
What is the function of oxygen in cellular respiration?
Correct Answer
B. To pick up electrons at the end of the electron transport chain
Explanation
Oxygen serves as the final electron acceptor at the end of the electron transport chain in cellular respiration. During the process of cellular respiration, electrons are passed along the electron transport chain, creating a flow of protons across the inner mitochondrial membrane. Oxygen then combines with these electrons and protons to form water, thus picking up the electrons and completing the chain. This process is crucial for the production of ATP, the main energy currency of the cell.
7.
Which of the following types of organisms uses cellular respiration for their cellular energy needs?
Correct Answer
A. Eukaryotes
Explanation
Eukaryotes use cellular respiration for their cellular energy needs. Cellular respiration is the process by which cells convert glucose and oxygen into carbon dioxide, water, and ATP (adenosine triphosphate), which is the main source of energy for cellular activities. Eukaryotes, which include plants, animals, fungi, and protists, have complex cellular structures and organelles, such as mitochondria, where cellular respiration takes place. Prokaryotes, on the other hand, lack mitochondria and have simpler cellular structures, relying on other mechanisms for energy production.
8.
Which process breaks down sugars to make ATP when oxygen is present?
Correct Answer
B. Cellular respiration
Explanation
Cellular respiration is the correct answer because it is the process by which cells break down sugars to produce ATP when oxygen is present. This process occurs in the mitochondria of cells and involves the conversion of glucose into carbon dioxide and water, releasing energy in the form of ATP. Anaerobic respiration is a process that occurs when oxygen is not present, glycolysis is the initial step of cellular respiration, and photosynthesis is the process by which plants convert sunlight into energy.
9.
The part of cellular respiration in which glucose is broken down is called
Correct Answer
D. Glycolysis.
Explanation
Glycolysis is the correct answer because it is the initial step in cellular respiration where glucose is broken down into two molecules of pyruvate. This process occurs in the cytoplasm and does not require oxygen, making it anaerobic. Photosynthesis, on the other hand, is the process by which plants convert sunlight into energy, while aerobic respiration and electron transport are subsequent steps in cellular respiration that require oxygen.
10.
Two products of the Krebs cycle are
Correct Answer
B. ATP and carbon dioxide.
Explanation
The Krebs cycle is a series of chemical reactions that occur in the mitochondria of cells, and it is an important part of cellular respiration. During the Krebs cycle, carbon dioxide is produced as a waste product, while ATP is generated as a form of energy currency for the cell. Therefore, the correct answer is ATP and carbon dioxide.
11.
What provides the electron transport chain in cellular respiration with the energy it needs to function?
Correct Answer
D. Krebs cycle
Explanation
The Krebs cycle, also known as the citric acid cycle, provides the electron transport chain in cellular respiration with the energy it needs to function. During the Krebs cycle, acetyl-CoA is oxidized and produces high-energy molecules such as NADH and FADH2. These molecules then transfer their electrons to the electron transport chain, where they generate ATP through oxidative phosphorylation. Therefore, the Krebs cycle plays a crucial role in supplying the energy required for the electron transport chain to function effectively.
12.
The electron transport chain produces water and ATP. Where do the hydrogen atoms come from that are used to form water?
Correct Answer
B. NADH and FADH2
Explanation
NADH and FADH2 are electron carriers that are produced during the citric acid cycle and glycolysis. These molecules donate their electrons to the electron transport chain, which is a series of protein complexes located in the inner mitochondrial membrane. As the electrons pass through the electron transport chain, they create a proton gradient across the membrane. This gradient drives the synthesis of ATP, and the electrons ultimately combine with oxygen to form water. Therefore, the hydrogen atoms used to form water in the electron transport chain come from NADH and FADH2.
13.
Which organelle converts molecules from the food you eat into usable energy?
Correct Answer
C. Mitochondrion
Explanation
The mitochondrion is the correct answer because it is the organelle responsible for converting molecules from the food we eat into usable energy in the form of ATP (adenosine triphosphate) through a process called cellular respiration. This energy is then used by the cell to carry out various functions and activities. The Golgi apparatus is involved in sorting, modifying, and packaging proteins, while chloroplasts are responsible for photosynthesis in plant cells. Lysosomes are involved in the breakdown and recycling of cellular waste materials.
14.
What is another name for the Krebs cycle?
Correct Answer
A. Citric acid cycle
Explanation
The correct answer is Citric acid cycle. The Krebs cycle is also known as the citric acid cycle. It is a series of chemical reactions that occur in the mitochondria of cells, where acetyl-CoA is oxidized and carbon dioxide, ATP, and high-energy electrons are produced. The cycle is named after Hans Krebs, the scientist who discovered it in the 1930s. The Calvin cycle, on the other hand, is a series of reactions that occur in photosynthetic organisms to convert carbon dioxide into glucose. Motor cycle and cell cycle are not related to the Krebs cycle.
15.
In the electron transport chain, hydrogen ions are pumped across the mitochondrial membrane. What provides the energy to operate the protein pumps?
Correct Answer
A. Electrons
Explanation
Electrons provide the energy to operate the protein pumps in the electron transport chain. As electrons move through the chain, they transfer energy to the protein pumps, allowing them to actively pump hydrogen ions across the mitochondrial membrane. This creates an electrochemical gradient, which is later used to generate ATP, the main energy currency of the cell. Oxygen is the final electron acceptor in the chain, while carbon dioxide is not directly involved in providing energy for the protein pumps.
16.
What enzyme is located at the end of the electron transport chain?
Correct Answer
A. ATP synthase
Explanation
ATP synthase is the correct answer because it is the enzyme located at the end of the electron transport chain. This enzyme is responsible for the synthesis of ATP, the main energy currency of the cell. It catalyzes the conversion of ADP (adenosine diphosphate) and inorganic phosphate into ATP through a process called oxidative phosphorylation. ATP synthase utilizes the energy generated from the flow of protons across the inner mitochondrial membrane to drive the synthesis of ATP.
17.
Which of the following is not a stage of cellular respiration?
Correct Answer
D. Calvin cycle
Explanation
The Calvin cycle is not a stage of cellular respiration. It is actually a series of chemical reactions that occur in the stroma of chloroplasts during photosynthesis. The Calvin cycle is responsible for converting carbon dioxide into glucose, using the energy from ATP and NADPH produced during the light-dependent reactions. In contrast, cellular respiration is the process by which cells convert glucose into ATP, and it consists of three stages: glycolysis, the Krebs cycle, and the electron transport chain.
18.
Which of the following stages occurs in the mitochondrial matrix?
Correct Answer
A. The cirtic acid cycle
Explanation
The correct answer is the citric acid cycle. The citric acid cycle, also known as the Krebs cycle, is a series of chemical reactions that occur in the mitochondrial matrix. It is an important part of cellular respiration and plays a crucial role in the production of energy in the form of ATP. During the citric acid cycle, acetyl-CoA is oxidized and carbon dioxide, ATP, NADH, and FADH2 are produced. This cycle takes place in the mitochondrial matrix, which is the innermost compartment of the mitochondria.
19.
The three-carbon molecule formed by glycolysis is ___.
Correct Answer
A. Pyruvate
Explanation
Glycolysis is the metabolic pathway that breaks down glucose into pyruvate. During glycolysis, a six-carbon glucose molecule is converted into two molecules of three-carbon pyruvate. Pyruvate is then further metabolized in various ways depending on the organism and the availability of oxygen. Therefore, the correct answer is pyruvate.
20.
In the diagram to the right, what is structure A?
Correct Answer
A. Folded inner membrane
21.
In the diagram to the right, what is structure B?
Correct Answer
B. Mitochondrial matrix
Explanation
Structure B in the diagram is the mitochondrial matrix. The mitochondrial matrix is the fluid-filled space inside the inner membrane of the mitochondria. It contains enzymes, DNA, and ribosomes, and is the site of several metabolic reactions, including the citric acid cycle.
22.
Where does the Krebs Cycle take place?
Correct Answer
A. Mitochondrial matrix
Explanation
The Krebs Cycle, also known as the citric acid cycle, takes place in the mitochondrial matrix. This is the innermost compartment of the mitochondria, where the enzymes and other molecules necessary for the cycle are located. The Krebs Cycle is an essential part of cellular respiration, where glucose is broken down to produce energy in the form of ATP.
23.
Where does the electron transport chain take place?
Correct Answer
B. Folded inner membrane
Explanation
The electron transport chain takes place in the folded inner membrane of the mitochondria. This membrane is highly folded to increase its surface area, allowing for more electron transport chain complexes to be present. The electron transport chain is a series of protein complexes embedded in the inner membrane that transfer electrons and generate a proton gradient. This gradient is then used to produce ATP through oxidative phosphorylation.
24.
How many net ATP can be produced from one molecule of glucose during aerobic respiration?
Correct Answer
A. 38 ATP
Explanation
During aerobic respiration, one molecule of glucose can produce a maximum of 38 ATP. This occurs through a series of biochemical reactions in the mitochondria, including glycolysis, the Krebs cycle, and oxidative phosphorylation. These processes generate energy in the form of ATP through the transfer of electrons in the electron transport chain. The net production of 38 ATP represents the maximum energy yield from one molecule of glucose during aerobic respiration.