Photosynthesis Flashcards

Photosynthesis Overview

• Chemical Formula: Photosynthesis is represented by the equation 6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂, demonstrating the transformation of carbon dioxide and water into glucose and oxygen.
• Location: Photosynthesis occurs in chloroplasts, specialized organelles within plant cells.

Inputs and Outputs

• Required Inputs: Essential components for photosynthesis include light, carbon dioxide, and water.
• Outputs: The process generates sugars (like glucose) and oxygen, crucial for life on Earth.

Light-Dependent Reactions

• Function: This phase utilizes light energy to produce ATP and NADPH, which are energy-carrying molecules.
• Process Details: Light energy is captured by chlorophyll, exciting electrons and facilitating the generation of energy carriers.

Light-Independent Reactions (Calvin Cycle)

• Process Description: Also known as the Calvin Cycle, this stage does not require light. It uses ATP and NADPH to synthesize high-energy compounds, primarily sugar.
• Role of Carbon Dioxide: Six molecules of carbon dioxide are utilized to ultimately create one molecule of glucose.

Role of Chloroplasts

• Chloroplast Structure: Chloroplasts consist of thylakoids (membranous sacs) arranged in stacks (grana) and the surrounding fluid matrix called stroma.
• Pigmentation: Various pigments, like chlorophyll a and b, capture different wavelengths of light, optimizing energy absorption for photosynthesis.

Importance of Water

• Water's Role: Water supplies the necessary electrons and hydrogen ions for the light-dependent and light-independent reactions, making it crucial for the entire process.
• Hydrogen and Electron Production: Electrons from water enable NADPH and ATP formation during the light-dependent phase.

ATP and NADPH

• ADP vs. ATP: ATP has an additional phosphate group compared to ADP, indicating higher energy storage capacity.
• NADPH Function: NADPH serves as an electron carrier, transferring high-energy electrons for sugar production during the light-independent reactions.

Electron Transport Chain (ETC)

• ETC Functionality: The energy from excited electrons is used to create a hydrogen ion concentration gradient across the thylakoid membrane, facilitating ATP synthesis.

Ecological Significance of Plants

• Life on Earth: Plants play a foundational role in ecosystems by converting solar energy into chemical energy in the form of sugars and oxygen, essential for most living organisms.

Summary of Photosynthesis Steps

• Light energy penetrates leaves and is captured by chlorophyll in chloroplasts.
• Water is split to produce hydrogen and oxygen; oxygen is released.
• NADPH and ATP are generated from the energy derived from light.
• Carbon dioxide enters the chloroplasts, and in the stroma, hydrogen and carbon combine to form carbohydrates.
• Energy-rich carbohydrates are distributed to plant cells for growth and energy.