Unit 3 Study Guide

Aerobic vs Anaerobic Respiration

• Aerobic Respiration

  • Occurs in the presence of oxygen.

  • Releases more energy.

  • Slower process.

  • Examples:

    • Human muscle activity

    • Plant respiration

• Anaerobic Respiration

  • Occurs without oxygen.

  • Releases less energy.

  • Faster process.

  • Examples:

    • Alcohol fermentation

    • Lactic acid fermentation

Photosynthesis: Light-Dependent vs Light-Independent Reactions

Light-Dependent Reactions

• Location:

  • Thylakoid membranes of chloroplasts

• Energy Source:

  • Require light energy (photons)

• Primary Function:

  • Convert light energy into chemical energy (ATP and NADPH)

• Inputs:

  • Water (H₂O), light energy, ADP, and NADP⁺

• Outputs:

  • Oxygen (O₂), ATP, and NADPH

• Key Processes:

  • Photolysis (splitting of water)

  • Generation of ATP via photophosphorylation

  • Reduction of NADP⁺ to NADPH

• Dependency on Light:

  • Directly dependent

• Byproduct:

  • Oxygen (O₂) is released

Light-Independent Reactions (Calvin Cycle)

• Location:

  • Stroma of chloroplasts

• Energy Source:

  • Use chemical energy (ATP and NADPH) from light-dependent reactions

• Primary Function:

  • Fix carbon dioxide into organic molecules (glucose)

• Inputs:

  • Carbon dioxide (CO₂), ATP, and NADPH

• Outputs:

  • Glucose (C₆H₁₂O₆), ADP, and NADP⁺

• Key Processes:

  • Carbon fixation (via RuBisCO)

  • Reduction phase

  • Regeneration of RuBP

• Dependency on Light:

  • Indirectly dependent (uses products from light-dependent reactions)

• Byproduct:

  • No gaseous byproducts

Summary

• Light-Dependent Reactions:

  • Capture and convert solar energy into chemical energy (ATP and NADPH) and release oxygen.

• Light-Independent Reactions:

  • Use chemical energy to synthesize glucose from carbon dioxide through enzyme-mediated steps.

Photosynthesis Input and Output

• Inputs:

  • Water, carbon dioxide, sunlight

• Outputs:

  • Glucose and oxygen

Cellular Respiration Process

• Equation:

  • Glucose + 2 NAD⁺ + 2 Pi + 2 ADP → 2 pyruvate + 2 NADH + 2 ATP + 2 H⁺ + 2 H₂O + energy

• Input and Output:

  • Inputs: Glucose, NAD⁺, Pi, ADP

  • Outputs: Pyruvate, NADH, ATP, H⁺, H₂O, energy

• ATP Synthesized:

  • 2 ATP molecules

Special Type of Photosynthesis

• Type:

  • Occurs in some organisms based on their environment.

• Distinction:

  • Regular photosynthesis primarily occurs in plants, algae, and some bacteria, producing oxygen and glucose

  • Alternative forms may differ in outputs or the type of organisms involved.

Anaerobic Processes During Exercise

• Process:

  • Lactic acid fermentation

• Reactant and Product:

  • Reactant: Glucose

  • Product: ATP and lactic acid

• Context:

  • Used by muscles during intense exercise when oxygen is insufficient.

Glycolysis

• Input and Output:

  • Inputs:

    • 1 glucose molecule

  • Outputs:

    • 2 pyruvate molecules

    • 4 ATP molecules (net gain of 2 ATP)

    • 2 NADH molecules

Chloroplast and Mitochondria Structure

• Chloroplasts:

  • Use sunlight to make glucose in the stroma

  • Store H⁺ ions in thylakoids

• Mitochondria:

  • Break down glucose into ATP in their cristae

  • Release CO₂ in the matrix

Energy Pyramid

• Description:

  • Shows energy flow from producers (plants) to consumers (herbivores, carnivores)

• Energy Transfer:

  • 10% of energy is transferred to the upper level

  • 90% is lost as heat

Carbon Cycle

• Storage:

  • Most carbon is stored in rocks and sediments

Nitrogen Cycle and Nitrogen-Fixing Bacteria

• Purpose:

  • Capture atmospheric nitrogen, convert it to ammonia

• Products:

  • Ammonia used by plants to create organic molecules

Outline of Cycles

• Phosphorus Cycle:

  • Moves through rocks, soil, and living things

• Water Cycle:

  • Moves through evaporation, rain, and rivers

• Oxygen Cycle:

  • Cycles between plants making it and animals using it