BackBIO 130L Quiz 3 Review: Cellular Respiration & Photosynthesis Study Guidance
Study Guide - Smart Notes
Tailored notes based on your materials, expanded with key definitions, examples, and context.
Q1. Explain reducing and oxidizing reactions.
Background
Topic: Redox (Reduction-Oxidation) Reactions in Biology
This question tests your understanding of how electrons are transferred between molecules during metabolic processes, such as cellular respiration and photosynthesis.
Key Terms and Concepts:
Oxidation: Loss of electrons from a molecule, atom, or ion.
Reduction: Gain of electrons by a molecule, atom, or ion.
Redox Reaction: A chemical reaction involving the transfer of electrons between two species.
Step-by-Step Guidance
Recall that in a redox reaction, one substance loses electrons (is oxidized) and another gains electrons (is reduced).
Remember the mnemonic "OIL RIG": Oxidation Is Loss (of electrons), Reduction Is Gain (of electrons).
Think about how, in cellular respiration, glucose is oxidized and oxygen is reduced.
Consider how these reactions are coupled—one cannot occur without the other.
Try explaining these concepts in your own words before checking the answer!
Final Answer:
Reducing reactions involve the gain of electrons (reduction), while oxidizing reactions involve the loss of electrons (oxidation). In biological systems, these reactions are essential for energy transfer, such as in cellular respiration where glucose is oxidized and oxygen is reduced.
Q2. What is the difference between aerobic respiration, anaerobic respiration, and fermentation?
Background
Topic: Types of Cellular Respiration
This question tests your understanding of how cells generate energy under different environmental conditions (presence or absence of oxygen).
Key Terms:
Aerobic Respiration: Cellular respiration that requires oxygen.
Anaerobic Respiration: Respiration that does not use oxygen but uses other electron acceptors.
Fermentation: Energy production in the absence of oxygen, without an electron transport chain.
Step-by-Step Guidance
Identify which process uses oxygen as the final electron acceptor (aerobic respiration).
Determine what alternative electron acceptors might be used in anaerobic respiration (e.g., nitrate, sulfate).
Recognize that fermentation does not use an electron transport chain and regenerates NAD+ by transferring electrons to organic molecules.
Compare the ATP yield of each process—think about which is most efficient.
Try to summarize the differences before revealing the answer!
Final Answer:
Aerobic respiration uses oxygen as the final electron acceptor and produces the most ATP. Anaerobic respiration uses other molecules as electron acceptors and produces less ATP. Fermentation does not use an electron transport chain and yields the least ATP, regenerating NAD+ by transferring electrons to organic molecules.
Q3. What is the simplified chemical reaction for cellular respiration? What is being reduced and what is being oxidized? What form of chemical energy is being generated by this process?
Background
Topic: Cellular Respiration Equation and Redox
This question tests your ability to recall the overall equation for cellular respiration, identify redox components, and recognize ATP as the energy currency.
Key Formula:
Glucose () is oxidized to carbon dioxide ().
Oxygen () is reduced to water ().
ATP is generated as the main energy product.
Step-by-Step Guidance
Write out the overall equation for cellular respiration.
Identify which molecule loses electrons (is oxidized) and which gains electrons (is reduced).
Determine what form of energy is produced and how it is used by the cell.
Try to write the equation and identify the redox components before checking the answer!
Final Answer:
The simplified equation is . Glucose is oxidized, oxygen is reduced, and ATP is the chemical energy generated.
Q4. What occurs during glycolysis: what is the starting material and what are the products? Where does glycolysis occur?
Background
Topic: Glycolysis in Cellular Respiration
This question tests your understanding of the first stage of cellular respiration, including substrates, products, and cellular location.
Key Terms:
Glycolysis: The breakdown of glucose to pyruvate, producing ATP and NADH.
Cytoplasm: The location in the cell where glycolysis occurs.
Step-by-Step Guidance
Identify the starting molecule for glycolysis (glucose).
List the main products of glycolysis (pyruvate, ATP, NADH).
Recall where in the cell glycolysis takes place (cytoplasm).
Try to recall the steps and products before revealing the answer!
Final Answer:
Glycolysis starts with glucose and produces pyruvate, ATP, and NADH. It occurs in the cytoplasm of the cell.
Q5. What occurs during the TCA/Krebs cycle: what is the starting material and what are the products? Where does it occur?
Background
Topic: Krebs Cycle (Citric Acid Cycle) in Cellular Respiration
This question tests your knowledge of the second stage of cellular respiration, including substrates, products, and cellular location.
Key Terms:
TCA/Krebs Cycle: A series of reactions that generate NADH, FADH2, and ATP from acetyl-CoA.
Mitochondrial Matrix: The location where the Krebs cycle occurs.
Step-by-Step Guidance
Identify the starting molecule for the Krebs cycle (acetyl-CoA).
List the main products (NADH, FADH2, ATP/GTP, CO2).
Recall the cellular location (mitochondrial matrix).
Try to list the products and location before checking the answer!
Final Answer:
The Krebs cycle starts with acetyl-CoA and produces NADH, FADH2, ATP (or GTP), and CO2. It occurs in the mitochondrial matrix.
Q6. What occurs during oxidative phosphorylation? Where does it occur? What are the roles of the electron transport chain, ATP synthase, and oxygen during oxidative phosphorylation?
Background
Topic: Oxidative Phosphorylation in Cellular Respiration
This question tests your understanding of the final stage of cellular respiration, focusing on the electron transport chain and ATP synthesis.
Key Terms:
Electron Transport Chain (ETC): Series of protein complexes that transfer electrons and pump protons.
ATP Synthase: Enzyme that synthesizes ATP using the proton gradient.
Oxygen: Final electron acceptor in the ETC.
Inner Mitochondrial Membrane: Location of oxidative phosphorylation.
Step-by-Step Guidance
Describe how electrons from NADH and FADH2 are transferred through the ETC.
Explain how the ETC pumps protons to create a gradient across the inner mitochondrial membrane.
Discuss how ATP synthase uses this gradient to produce ATP.
Identify the role of oxygen as the final electron acceptor, forming water.
Try to outline the process before revealing the answer!
Final Answer:
During oxidative phosphorylation, electrons pass through the ETC, protons are pumped to create a gradient, and ATP synthase uses this gradient to make ATP. Oxygen acts as the final electron acceptor, forming water. This process occurs in the inner mitochondrial membrane.
Q7. Know the parts of the mitochondria—outer membrane, inner membrane, intermembrane space, and matrix.
Background
Topic: Mitochondrial Structure
This question tests your ability to identify and describe the main structural components of mitochondria.
Key Terms:
Outer Membrane: The smooth outer covering of the mitochondrion.
Inner Membrane: The highly folded membrane inside the mitochondrion.
Intermembrane Space: The space between the outer and inner membranes.
Matrix: The innermost compartment containing enzymes for the Krebs cycle.
Step-by-Step Guidance
Visualize or sketch a mitochondrion and label each part.
Recall the function of each part (e.g., where the ETC is located, where the Krebs cycle occurs).
Think about how the structure supports the function of cellular respiration.
Try to label a diagram before checking the answer!
Final Answer:
The mitochondrion consists of an outer membrane, inner membrane (with cristae), intermembrane space, and matrix. The inner membrane houses the ETC, and the matrix contains enzymes for the Krebs cycle.
Q8. How does the reaction of fermentation allow glycolysis to occur in the absence of oxygen/oxidative phosphorylation? What two reactants of glycolysis are the products of alcohol fermentation?
Background
Topic: Fermentation and Glycolysis
This question tests your understanding of how cells regenerate NAD+ to keep glycolysis running when oxygen is not available.
Key Terms:
Fermentation: Process that allows glycolysis to continue by regenerating NAD+.
Alcohol Fermentation: Converts pyruvate to ethanol and CO2, regenerating NAD+.
Step-by-Step Guidance
Recall that glycolysis requires NAD+ to accept electrons.
Explain how, in the absence of oxygen, fermentation regenerates NAD+ by reducing pyruvate.
Identify the products of alcohol fermentation (ethanol and CO2) and relate them to glycolysis intermediates.
Try to connect glycolysis and fermentation before revealing the answer!
Final Answer:
Fermentation regenerates NAD+ so glycolysis can continue without oxygen. The products of alcohol fermentation are ethanol and CO2, which are derived from pyruvate, a glycolysis product.
Q9. Which laboratory organism can be used to study alcohol fermentation?
Background
Topic: Model Organisms in Fermentation Studies
This question tests your knowledge of common organisms used in laboratory studies of fermentation.
Key Term:
Yeast (Saccharomyces cerevisiae): A eukaryotic microorganism commonly used to study alcohol fermentation.
Step-by-Step Guidance
Recall which organisms are capable of alcohol fermentation.
Think about which are commonly used in labs for bread, beer, or wine production.
Identify the scientific name of the most common laboratory yeast.
Try to recall the organism before checking the answer!
Final Answer:
Yeast, specifically Saccharomyces cerevisiae, is commonly used to study alcohol fermentation in the laboratory.
Q10. Explain the difference between autotrophs and heterotrophs. Of the major groups of organisms (prokaryotes, fungi, plants, animals, protists), which groups contain species that are autotrophs and which contain species that are heterotrophs?
Background
Topic: Nutritional Modes in Biology
This question tests your understanding of how organisms obtain energy and carbon.
Key Terms:
Autotrophs: Organisms that produce their own food from inorganic sources (e.g., plants via photosynthesis).
Heterotrophs: Organisms that obtain food by consuming other organisms.
Step-by-Step Guidance
Define autotrophs and heterotrophs.
List which major groups contain autotrophic species (e.g., plants, some protists, some prokaryotes).
List which groups contain heterotrophic species (e.g., animals, fungi, some protists, some prokaryotes).
Note that some groups (prokaryotes, protists) have both types.
Try to categorize each group before revealing the answer!
Final Answer:
Autotrophs make their own food; heterotrophs consume others. Plants and some protists/prokaryotes are autotrophs; animals, fungi, and some protists/prokaryotes are heterotrophs.
Q11. What is the simplified equation for photosynthesis? Is this an exergonic or endergonic reaction? Which molecules are reduced and which are oxidized?
Background
Topic: Photosynthesis Equation and Redox
This question tests your ability to recall the overall equation for photosynthesis, classify the reaction, and identify redox components.
Key Formula:
CO2 is reduced to glucose.
H2O is oxidized to O2.
Photosynthesis is an endergonic reaction (requires energy input).
Step-by-Step Guidance
Write the overall equation for photosynthesis.
Identify which molecules are oxidized and which are reduced.
Determine if the reaction absorbs or releases energy.
Try to write the equation and classify the reaction before checking the answer!
Final Answer:
The equation is . CO2 is reduced, H2O is oxidized, and the reaction is endergonic.
Q12. What occurs during the light reactions? What is the starting material and what is produced? What are the components of PSII and PSI? Which pigments are found in light harvesting complexes and what are their roles? How do pigments work? Why do they appear to us to have a certain color?
Background
Topic: Light Reactions of Photosynthesis
This question tests your understanding of the first stage of photosynthesis, including the roles of pigments and photosystems.
Key Terms:
Light Reactions: Convert light energy to chemical energy (ATP, NADPH).
Photosystem II (PSII) and Photosystem I (PSI): Protein complexes involved in light absorption and electron transport.
Pigments: Chlorophyll a, chlorophyll b, carotenoids.
Step-by-Step Guidance
Identify the starting materials (light, water, ADP, NADP+).
List the products (ATP, NADPH, O2).
Describe the roles of PSII and PSI in electron transport.
Explain how pigments absorb specific wavelengths and reflect others, giving them color.
Relate pigment color to the wavelengths they do not absorb.
Try to outline the process and pigment roles before revealing the answer!
Final Answer:
Light reactions use light and water to produce ATP, NADPH, and O2. PSII and PSI contain chlorophyll and carotenoids, which absorb light. Pigments appear colored because they reflect certain wavelengths.
Q13. Where do the light reactions take place?
Background
Topic: Chloroplast Structure and Function
This question tests your knowledge of the cellular location of the light reactions in photosynthesis.
Key Term:
Thylakoid Membrane: The site of the light reactions in chloroplasts.
Step-by-Step Guidance
Recall the structure of the chloroplast and the location of thylakoids.
Identify where the protein complexes for the light reactions are embedded.
Try to recall the location before checking the answer!
Final Answer:
The light reactions take place in the thylakoid membrane of the chloroplast.
Q14. How does the light reaction produce ATP?
Background
Topic: Photophosphorylation in Photosynthesis
This question tests your understanding of how light energy is converted into chemical energy (ATP) during photosynthesis.
Key Terms:
Electron Transport Chain: Transfers electrons and pumps protons.
ATP Synthase: Enzyme that synthesizes ATP using the proton gradient.
Photophosphorylation: The process of ATP formation using light energy.
Step-by-Step Guidance
Describe how light excites electrons in chlorophyll, starting electron flow through the ETC.
Explain how the ETC pumps protons into the thylakoid space, creating a gradient.
Discuss how ATP synthase uses this gradient to produce ATP from ADP and Pi.
Try to outline the process before revealing the answer!
Final Answer:
Light energy drives electron flow, creating a proton gradient across the thylakoid membrane. ATP synthase uses this gradient to synthesize ATP (photophosphorylation).
Q15. What occurs during the Calvin Cycle? What enzyme is responsible for fixing carbon? Where does the Calvin Cycle take place?
Background
Topic: Calvin Cycle (Light-Independent Reactions)
This question tests your understanding of the second stage of photosynthesis, including carbon fixation and the enzyme involved.
Key Terms:
Calvin Cycle: Series of reactions that fix CO2 into organic molecules.
Rubisco: The enzyme that catalyzes carbon fixation.
Stroma: The location in the chloroplast where the Calvin Cycle occurs.
Step-by-Step Guidance
Describe the main purpose of the Calvin Cycle (carbon fixation).
Identify the enzyme responsible for incorporating CO2 into organic molecules (Rubisco).
Recall the location of the Calvin Cycle (stroma of the chloroplast).
Try to recall the enzyme and location before checking the answer!
Final Answer:
The Calvin Cycle fixes CO2 into sugars using the enzyme Rubisco. It occurs in the stroma of the chloroplast.
Q16. What is chromatography? Why does the solvent have hydrophobic properties/why do we not use water? (Think about where photosynthetic pigments are found in the cell—is this environment hydrophobic or hydrophilic?)
Background
Topic: Chromatography and Pigment Separation
This question tests your understanding of how chromatography separates pigments based on their solubility and the properties of the solvent.
Key Terms:
Chromatography: Technique for separating mixtures based on solubility and affinity for the solvent.
Hydrophobic Solvent: Nonpolar solvent used to dissolve nonpolar pigments.
Step-by-Step Guidance
Define chromatography and its purpose in pigment separation.
Explain why a hydrophobic (nonpolar) solvent is used instead of water.
Relate the solubility of pigments to their location in the chloroplast (thylakoid membrane is hydrophobic).
Try to explain the reasoning before revealing the answer!
Final Answer:
Chromatography separates pigments based on solubility. Hydrophobic solvents are used because photosynthetic pigments are nonpolar and found in the hydrophobic thylakoid membrane, so water would not dissolve them well.
Q17. Know the parts of the chloroplast—outer membrane, inner membrane, thylakoid membrane, thylakoid space, thylakoid disks, granum, stroma.
Background
Topic: Chloroplast Structure
This question tests your ability to identify and describe the main structural components of chloroplasts.
Key Terms:
Outer Membrane: The outermost layer of the chloroplast.
Inner Membrane: The membrane just inside the outer membrane.
Thylakoid Membrane: The site of the light reactions.
Thylakoid Space (Lumen): The internal space of the thylakoid.
Thylakoid Disks: Flattened sacs that make up the thylakoid membrane system.
Granum (pl. Grana): Stack of thylakoid disks.
Stroma: The fluid-filled space surrounding the grana, site of the Calvin Cycle.
Step-by-Step Guidance
Visualize or sketch a chloroplast and label each part.
Recall the function of each part (e.g., where light reactions and Calvin Cycle occur).
Think about how the structure supports the function of photosynthesis.
Try to label a diagram before checking the answer!
Final Answer:
The chloroplast consists of an outer membrane, inner membrane, thylakoid membrane (forming disks), thylakoid space, grana (stacks of disks), and stroma. Light reactions occur in the thylakoid membrane; the Calvin Cycle occurs in the stroma.
