Exam 3 Biology 111 Study Guide: Cellular Respiration, Mitosis & Meiosis, Inheritance, and DNA Structure

Q1. What kind of energy change is associated with the citric acid cycle? (Is it endergonic or exergonic?)

Background

Topic: Cellular Respiration – Citric Acid Cycle

This question tests your understanding of the energy transformations that occur during the citric acid (Krebs) cycle, a key metabolic pathway in cellular respiration.

Key Terms:

• Endergonic: A reaction that requires energy input.

• Exergonic: A reaction that releases energy.

• Citric Acid Cycle: Also called the Krebs cycle; a series of chemical reactions used by all aerobic organisms to generate energy.

Step-by-Step Guidance

1. Recall that the citric acid cycle is part of cellular respiration, which is the process cells use to extract energy from nutrients.

2. Think about whether the cycle as a whole releases energy or requires energy input. Consider what happens to the high-energy electrons and ATP during the cycle.

3. Remember that the products of the cycle include NADH and FADH2, which are energy carriers, as well as ATP (or GTP) and CO2.

4. Ask yourself: Does the cycle result in a net release or absorption of energy?

Try solving on your own before revealing the answer!

Q2. Know the stages of Respiration: Glycolysis, Pyruvate oxidation, Krebs Cycle, and the ETC. Know what is added to the cycle (ATP, NAD+, etc.) and what comes out.

Background

Topic: Cellular Respiration Pathways

This question tests your ability to identify the main stages of cellular respiration and the key inputs and outputs of each stage.

Key Terms:

• Glycolysis: The breakdown of glucose into pyruvate, producing ATP and NADH.

• Pyruvate Oxidation: Conversion of pyruvate to acetyl-CoA, producing NADH and CO2.

• Krebs Cycle (Citric Acid Cycle): Series of reactions that generate NADH, FADH2, ATP, and CO2.

• Electron Transport Chain (ETC): Uses NADH and FADH2 to produce ATP via oxidative phosphorylation.

Step-by-Step Guidance

1. List the four main stages of cellular respiration in order: Glycolysis, Pyruvate Oxidation, Krebs Cycle, and ETC.

2. For each stage, identify the main reactants (what goes in) and products (what comes out). For example, glycolysis uses glucose and produces pyruvate, ATP, and NADH.

3. Consider which molecules are added (e.g., NAD+, FAD, ADP) and which are produced (e.g., NADH, FADH2, ATP, CO2).

4. Make a table or diagram to organize the inputs and outputs for each stage.

Try organizing the information before checking the answer!

Q3. Be able to label the diagram of the cycle with the reactants and products.

Background

Topic: Citric Acid Cycle (Krebs Cycle) Diagram

This question tests your ability to visually identify and label the key molecules involved in the citric acid cycle.

Key Terms:

• Reactants: Substances consumed during the cycle (e.g., Acetyl-CoA, NAD+).

• Products: Substances produced (e.g., NADH, FADH2, CO2, ATP).

Step-by-Step Guidance

1. Review a diagram of the citric acid cycle and identify the entry point (Acetyl-CoA joining with oxaloacetate).

2. Label where NAD+ and FAD are reduced to NADH and FADH2.

3. Mark where ATP (or GTP) is produced and where CO2 is released.

4. Check that you can match each reactant and product to the correct step in the cycle.

Try labeling a blank diagram before checking the answer!

Q4. Where does each stage of cellular respiration happen?

Background

Topic: Cellular Respiration – Compartmentalization

This question tests your knowledge of the cellular locations where each stage of respiration occurs.

Key Terms:

• Cytoplasm: Fluid part of the cell outside organelles.

• Mitochondria: Organelle where most respiration steps occur.

• Mitochondrial Matrix: Innermost compartment of mitochondria.

• Inner Mitochondrial Membrane: Site of the electron transport chain.

Step-by-Step Guidance

1. Recall that glycolysis occurs in the cytoplasm.

2. Remember that pyruvate oxidation and the Krebs cycle take place in the mitochondrial matrix.

3. Know that the electron transport chain is located in the inner mitochondrial membrane.

4. Try to match each stage to its correct cellular location.

Test yourself by matching stages to locations before checking the answer!

Q5. Why is it important that the electrons are passed down the electron transport chain?

Background

Topic: Electron Transport Chain (ETC) Function

This question tests your understanding of the role of the ETC in energy production during cellular respiration.

Key Terms:

• Electron Transport Chain: Series of protein complexes that transfer electrons and pump protons.

• ATP Synthesis: The process of making ATP using the energy from the ETC.

• Proton Gradient: Difference in proton concentration across the inner mitochondrial membrane.

Step-by-Step Guidance

1. Recall that electrons from NADH and FADH2 are transferred through the ETC.

2. Understand that as electrons move through the chain, energy is released and used to pump protons across the membrane.

3. Consider why creating a proton gradient is essential for ATP production.

4. Think about what would happen if electrons were not passed down the chain.

Reflect on the importance of the ETC before checking the answer!

Q6. Why does your respiration rate increase when you are exercising (explain in context of the citric acid cycle)?

Background

Topic: Cellular Respiration and Exercise

This question tests your understanding of how increased energy demand during exercise affects cellular respiration, especially the citric acid cycle.

Key Terms:

• Respiration Rate: The rate at which cells consume oxygen and produce carbon dioxide.

• ATP Demand: The need for more ATP during physical activity.

• Citric Acid Cycle: Central pathway for energy production.

Step-by-Step Guidance

1. Recognize that exercise increases the demand for ATP in muscle cells.

2. Recall that the citric acid cycle is a major source of ATP (indirectly, via NADH and FADH2).

3. Understand that increased ATP demand leads to increased rates of the citric acid cycle and electron transport chain.

4. Think about how this increased activity requires more oxygen and produces more CO2, raising your respiration rate.

Try explaining this process in your own words before checking the answer!

Q7. What is an electron acceptor and why does it accept an electron? What does the electron acceptor do with the electron?

Background

Topic: Redox Reactions in Cellular Respiration

This question tests your understanding of electron acceptors and their role in cellular respiration.

Key Terms:

• Electron Acceptor: A molecule that gains electrons during a redox reaction.

• Redox Reaction: Chemical reaction involving the transfer of electrons.

• Oxygen: The final electron acceptor in aerobic respiration.

Step-by-Step Guidance

1. Define what an electron acceptor is in the context of cellular respiration.

2. Explain why electron acceptors are necessary for the flow of electrons in metabolic pathways.

3. Describe what happens to the electron after it is accepted (e.g., formation of water in aerobic respiration).

4. Consider the consequences if there were no electron acceptors available.

Try to answer these questions before checking the answer!

Q8. What is oxygen used for during cellular respiration? Why do you need oxygen to live?

Background

Topic: Role of Oxygen in Cellular Respiration

This question tests your understanding of why oxygen is essential for aerobic organisms.

Key Terms:

• Final Electron Acceptor: Oxygen's role in the electron transport chain.

• ATP Production: Oxygen enables efficient ATP synthesis.

• Water Formation: Oxygen combines with electrons and protons to form water.

Step-by-Step Guidance

1. Recall that oxygen is the final electron acceptor in the electron transport chain.

2. Understand that without oxygen, the ETC cannot function, and ATP production is severely limited.

3. Explain how oxygen's role in accepting electrons prevents the backup of electrons and allows continued energy production.

4. Think about what happens to cells and organisms if oxygen is not available.

Try to explain the importance of oxygen before checking the answer!

Q9. What does one glucose molecule make throughout the Citric Acid cycle (hint: the cycle runs 2x for each glucose)?

Background

Topic: Citric Acid Cycle Yield per Glucose

This question tests your ability to calculate the total products generated from one glucose molecule during the citric acid cycle.

Key Terms:

• Glucose: One molecule yields two pyruvate molecules, each entering the cycle.

• NADH, FADH2, ATP (or GTP), CO2: Main products of the cycle.

Step-by-Step Guidance

1. Recall that each glucose produces two acetyl-CoA molecules, so the cycle turns twice per glucose.

2. List the products generated per turn of the cycle (e.g., NADH, FADH2, ATP, CO2).

3. Multiply each product by two to get the total per glucose molecule.

4. Organize your answer in a table or list for clarity.

Try calculating the totals before checking the answer!

Q10. Anaerobic and aerobic respiration: how do they differ? What are the differences between fermentation and the lactic acid cycle?

Background

Topic: Types of Respiration and Fermentation

This question tests your understanding of the differences between aerobic and anaerobic respiration, as well as between fermentation and lactic acid fermentation.

Key Terms:

• Aerobic Respiration: Uses oxygen as the final electron acceptor.

• Anaerobic Respiration: Uses other molecules as electron acceptors.

• Fermentation: Process that allows glycolysis to continue without oxygen.

• Lactic Acid Fermentation: Produces lactic acid as a byproduct.

Step-by-Step Guidance

1. Define aerobic and anaerobic respiration, focusing on the presence or absence of oxygen.

2. Explain how fermentation allows cells to regenerate NAD+ in the absence of oxygen.

3. Describe the main differences between alcoholic fermentation and lactic acid fermentation.

4. Compare the energy yields of each process.

Try outlining the differences before checking the answer!

Q11. What is the function of cellular respiration? Write out the basic formula and list why each reactant is necessary.

Background

Topic: Cellular Respiration Overview

This question tests your understanding of the overall purpose of cellular respiration and the chemical equation involved.

Key Terms and Formula:

• Cellular Respiration: Process of converting glucose and oxygen into ATP, CO2, and water.

Key Formula:

$\text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O} + \text{ATP}$

Step-by-Step Guidance

1. Write out the balanced equation for cellular respiration.

2. Identify each reactant (glucose and oxygen) and each product (carbon dioxide, water, ATP).

3. Explain the role of each reactant in the process (e.g., glucose as fuel, oxygen as electron acceptor).

4. Describe why each reactant is necessary for efficient ATP production.

Try writing the equation and explaining each part before checking the answer!