Comprehensive Study Guidance for Biology 104 Exam 3 Topics

Q1. What are the inputs and outputs of the light reactions and the Calvin cycle? Where do the inputs come from? Where do the outputs go?

Background

Topic: Photosynthesis (Light Reactions and Calvin Cycle)

This question tests your understanding of the two main stages of photosynthesis, including the substances required and produced in each stage, and the flow of energy and matter through the process.

Key Terms and Concepts:

• Light reactions: Occur in the thylakoid membranes, use light energy to produce ATP and NADPH.

• Calvin cycle: Occurs in the stroma, uses ATP and NADPH to fix carbon dioxide into sugars.

• Inputs: Substances required for each stage (e.g., water, CO2, light).

• Outputs: Products generated (e.g., O2, glucose, NADP+, ADP).

Step-by-Step Guidance

1. List the main reactants (inputs) and products (outputs) for the light reactions. Consider where each comes from (e.g., water from the environment, light from the sun).

2. Identify the main reactants and products for the Calvin cycle. Think about which molecules are recycled and which are newly produced.

3. For each input and output, specify its source or destination (e.g., O2 released to atmosphere, ATP used in Calvin cycle).

4. Consider how the products of the light reactions are used in the Calvin cycle, and vice versa.

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Q2. What happens in the thylakoid vs. what happens in the stroma of the chloroplast?

Background

Topic: Chloroplast Structure and Function

This question focuses on the compartmentalization of photosynthetic processes within the chloroplast and the specific roles of the thylakoid and stroma.

Key Terms:

• Thylakoid: Membrane-bound sacs where light reactions occur.

• Stroma: Fluid-filled space surrounding thylakoids; site of the Calvin cycle.

Step-by-Step Guidance

1. Recall which stage of photosynthesis occurs in the thylakoid and which in the stroma.

2. Describe the main events or processes that take place in each compartment.

3. Think about the movement of molecules (e.g., ATP, NADPH) between these regions.

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Q3. What is the role of the thylakoid membrane in photosynthesis?

Background

Topic: Photosynthetic Membranes

This question examines your understanding of how the thylakoid membrane facilitates the light-dependent reactions of photosynthesis.

Key Terms:

• Thylakoid membrane: Contains photosystems, electron transport chain, and ATP synthase.

• Proton gradient: Essential for ATP synthesis.

Step-by-Step Guidance

1. Identify the main protein complexes embedded in the thylakoid membrane.

2. Explain how the thylakoid membrane contributes to the generation of a proton gradient.

3. Describe how this gradient is used to produce ATP.

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Q4. How do the inputs and outputs of cellular respiration and photosynthesis ‘match up’ with one another? What are the consequences of this for the biosphere?

Background

Topic: Relationship Between Photosynthesis and Cellular Respiration

This question tests your ability to compare and contrast the two processes and understand their ecological significance.

Key Terms:

• Photosynthesis: Converts CO2 and H2O into glucose and O2.

• Cellular respiration: Converts glucose and O2 into CO2 and H2O.

• Biosphere: The global sum of all ecosystems.

Step-by-Step Guidance

1. Write out the overall equations for photosynthesis and cellular respiration.

2. Compare the reactants and products of each process.

3. Discuss how these processes are interconnected in the biosphere (e.g., cycling of carbon and oxygen).

4. Consider the implications for energy flow and ecosystem function.

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Q5. What is the relationship between the electron transport chain and the photosystems of photosynthesis?

Background

Topic: Light Reactions of Photosynthesis

This question focuses on how the electron transport chain (ETC) and photosystems I and II work together during the light reactions.

Key Terms:

• Photosystem II (PSII) and Photosystem I (PSI): Protein complexes that absorb light and transfer electrons.

• Electron transport chain: Series of molecules that transfer electrons and pump protons.

Step-by-Step Guidance

1. Identify the sequence of events starting from light absorption in PSII.

2. Describe how electrons move through the ETC and reach PSI.

3. Explain the role of the ETC in generating a proton gradient and reducing NADP+.

Try solving on your own before revealing the answer!