Biology Chapter 8 Test Review

Energy Cycle

• CO2 enters chloroplasts, undergoing photosynthesis to produce O2 and glucose.
• The process of cellular respiration uses glucose and O2 to release energy, producing CO2 and H2O.

Photosynthesis

• Takes place in the chloroplast, a subcellular structure found in plant cells.
• Organisms that photosynthesize primarily include plants.
• Chemical equation: 6CO2 + 12H2O + light → C6H12O6 + 6O2 + H2O.
• Process converts light energy into chemical energy stored in glucose.

Cellular Respiration

• Occurs in the mitochondria, also a subcellular structure.
• All organisms with mitochondria perform cellular respiration, including plants and animals.
• Equation: C6H12O6 → CO2 + H2O + energy (ATP).

Relationship Between Photosynthesis and Cellular Respiration

• Both processes can occur in the same organism; plants perform both for energy.
• Photosynthesis produces glucose and oxygen, used by the plant for cellular respiration, generating energy.
• The ultimate energy source for nearly all living organisms is sunlight.

Photosynthesis Process

• Begins with light energy transformed into chemical energy, then stored in glucose.
• Purpose: Produce energy for producers (autotrophs).
• The term "photosynthesis" combines "photo" (light) and "synthesis" (producing).

Light Reactions and Calvin Cycle

• Light reactions occur in thylakoids; they convert solar energy to chemical energy (ATP and NADPH).
• The Calvin Cycle takes place in the stroma, using ATP and NADPH to synthesize glucose from carbon dioxide.
• Light reactions require sunlight directly, while the Calvin Cycle does not; it relies on products from light reactions.

Chlorophyll and Plant Structure

• Chlorophyll appears green because it absorbs all other colors of light while reflecting green and some blue light.
• Chloroplast structure: consists of thylakoids arranged in stacks called granum.

Gas Exchange

• Photosynthesis and cellular respiration are interconnected through the exchange of gases: oxygen and carbon dioxide.