Comprehensive Study Guidance for Biology 104 Exam 3 Topics

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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 that enter and leave each stage, and their sources and destinations.

Key Terms and Concepts:

Light reactions
Calvin cycle (dark reactions)
Inputs: water, carbon dioxide, light energy, NADP+, ADP
Outputs: oxygen, ATP, NADPH, glucose (or G3P)

Step-by-Step Guidance

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).
Identify the main reactants and products for the Calvin cycle. Think about which molecules are produced by the light reactions and used in the Calvin cycle.
For each input and output, specify its source (e.g., atmosphere, water, previous reaction) and its destination (e.g., released as gas, used in next step, stored as sugar).
Consider how the two stages are connected by the flow of energy and molecules (ATP, NADPH).

Try solving on your own before revealing the answer!

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

Background

Topic: Chloroplast Structure and Function

This question is about compartmentalization within the chloroplast and the specific processes that occur in each region.

Key Terms:

Thylakoid: membrane-bound sacs inside chloroplasts
Stroma: fluid-filled space surrounding thylakoids
Light reactions, Calvin cycle

Step-by-Step Guidance

Recall which stage of photosynthesis occurs in the thylakoid membranes and what is produced there.
Identify which stage occurs in the stroma and what is synthesized there.
Think about why these processes are separated into different compartments.

Try solving on your own before revealing the answer!

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

Background

Topic: Photosynthetic Membranes

This question focuses on the function of the thylakoid membrane in capturing light energy and facilitating electron transport.

Key Terms:

Photosystems
Electron transport chain
ATP synthase
Proton gradient

Step-by-Step Guidance

Describe how the thylakoid membrane houses the components necessary for the light reactions.
Explain how the membrane helps establish a proton gradient.
Consider how this gradient is used to generate ATP.

Try solving on your own before revealing the answer!

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 examines the cyclical nature of these two processes and their ecological significance.

Key Terms:

Photosynthesis:
Cellular respiration:
Biosphere, carbon cycle, oxygen cycle

Step-by-Step Guidance

Write out the overall equations for both processes and compare the reactants and products.
Identify how the outputs of one process serve as the inputs for the other.
Discuss the importance of this relationship for life on Earth (e.g., recycling of gases, energy flow).

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

Background

Topic: Light Reactions – Electron Flow

This question is about how light energy is used to move electrons through a series of proteins, generating ATP and NADPH.

Key Terms:

Photosystem II, Photosystem I
Electron transport chain (ETC)
ATP, NADPH

Step-by-Step Guidance

Describe the role of each photosystem in capturing light energy and exciting electrons.
Explain how electrons move from water through the photosystems and the ETC.
Discuss how this movement leads to the production of ATP and NADPH.

Try solving on your own before revealing the answer!

Q6. How is the increased H+ concentration in the thylakoid generated?

Background

Topic: Chemiosmosis in Photosynthesis

This question focuses on the mechanisms that create a proton gradient across the thylakoid membrane.

Key Terms:

Water splitting (photolysis)
Electron transport chain
Proton pumps

Step-by-Step Guidance

Identify the steps in the light reactions where protons are released into the thylakoid lumen.
Explain how the movement of electrons through the ETC contributes to proton accumulation.
Consider the role of water splitting at Photosystem II.

Try solving on your own before revealing the answer!

Q7. What is the role of ATP synthase in the light reaction and how does it compare to its role in cellular respiration?

Background

Topic: ATP Production in Cells

This question compares the function of ATP synthase in chloroplasts and mitochondria.

Key Terms:

ATP synthase
Proton gradient
Photophosphorylation vs. oxidative phosphorylation

Step-by-Step Guidance

Describe how ATP synthase uses the proton gradient to generate ATP in the chloroplast.
Compare this process to ATP production in mitochondria during cellular respiration.
Identify similarities and differences in the source of the proton gradient and the location of the enzyme.

Try solving on your own before revealing the answer!

Q8. What does ‘carbon fixation’ refer to in the context of photosynthesis? When/where does it occur?

Background

Topic: Calvin Cycle – Carbon Fixation

This question is about the process by which inorganic carbon is incorporated into organic molecules.

Key Terms:

Carbon fixation
Calvin cycle
RuBisCO
Stroma

Step-by-Step Guidance

Define carbon fixation in your own words.
Identify the enzyme responsible for this process and the location within the chloroplast.
Describe when during photosynthesis this step occurs.