Plant Growth and Biochemical Processes

Plant Growth Requirements

• Water is vital for photosynthesis, nutrient transport, and plant structure.
• Light is needed for photosynthesis, providing energy.
• Nutrients (nitrogen, phosphorus, potassium, trace elements) are essential for growth.
• Temperature affects enzyme activity and metabolic rates.
• Space is needed for root and shoot growth and sunlight access.

Producers and Autotrophs

• Producers create their own food (plants, algae, some bacteria).
• Autotrophs produce their own food.
  • Photoautotrophs use light energy (plants).
  • Chemoautotrophs use chemical energy (certain bacteria).

Biochemical Reactions in Plants

• Photosynthesis converts light energy into chemical energy stored in glucose.
• Light is crucial for the light-dependent reactions of photosynthesis.

Dehydration Synthesis and Hydrolysis

• Dehydration synthesis joins molecules by removing water.
• Hydrolysis breaks down molecules by adding water.

Water & Biomolecules

Water Structure and Properties

• Water's molecular formula is H₂O.
• Water is a polar molecule (unequal electron sharing).
• Hydrogen bonds form between water molecules.
• Water is cohesive (sticks to itself) and adhesive (sticks to other substances).
• Water has a high specific heat (absorbs heat without significant temperature change).
• Water is a universal solvent (dissolves many substances).

Types of Biomolecules

• Carbohydrates: Energy storage and structure (sugars, starches).
• Lipids: Energy storage, membrane structure, and insulation (fats, oils).
• Proteins: Catalysts (enzymes), structure, transport, and immune function.
• Nucleic Acids: Store and transmit genetic information (DNA, RNA).

Organic vs. Inorganic

• Organic molecules contain carbon and hydrogen (carbohydrates, proteins).
• Inorganic molecules lack significant carbon (water, salts).

Structural Differences

• Carbohydrates are chains of sugar molecules (saccharides).
• Lipids are long chains of hydrocarbons (fatty acids).
• Proteins are chains of amino acids.
• Nucleic acids are chains of nucleotides.

Enzyme Functionality

• Enzymes are proteins that speed up reactions without being consumed.
• Enzyme activity is specific to substrates and affected by temperature and pH.

Energy Storage

• Plants store energy as starch.
• Animals store energy as glycogen.

Photosynthesis

Organelles and Components

• Chlorophyll absorbs light energy.
• Chloroplasts are the organelles where photosynthesis occurs.
• Thylakoid membranes have light-dependent reactions.
• Grana are stacks of thylakoids.
• Stroma is fluid around thylakoids (Calvin Cycle).
• Stomata allow gas exchange (CO₂ in, O₂ out).

ATP and ADP

• ATP (Adenosine Triphosphate) is a primary energy carrier.
• ADP (Adenosine Diphosphate) is the lower-energy form of ATP.

Photosynthesis Reactions

• Light-dependent reactions (thylakoid membrane): Inputs: light, H₂O. Outputs: ATP, NADPH, O₂.
• Light-independent reactions (Calvin Cycle, stroma): Inputs: CO₂, ATP, NADPH. Outputs: glucose.

Balanced Photosynthesis Equation

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂

Factors Affecting Photosynthesis

• Light intensity affects reaction rate.
• CO₂ concentration affects reaction rate.
• Temperature affects enzyme activity (up to a point).

Respiration

Heterotrophs

• Heterotrophs obtain energy by consuming other organisms (animals, fungi).

Mitochondria

• Mitochondria are the sites of aerobic respiration.

Organisms That Respire

• All animals, plants, fungi, and most microorganisms.

ATP Production

• Aerobic respiration produces 36-38 ATP/glucose.
• Anaerobic respiration (fermentation) produces 2 ATP/glucose.

Fermentation Types

• Lactic acid fermentation produces lactic acid.
• Alcoholic fermentation produces ethanol and CO₂.

Aerobic Respiration Inputs/Outputs

• Inputs: glucose (C₆H₁₂O₆), O₂.
• Outputs: CO₂, H₂O, ATP.

Balanced Aerobic Respiration Equation

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 36-38 ATP

Factors Affecting Respiration

• Oxygen availability affects rate.
• Temperature affects enzyme activity (up to a point).

Carbon Cycle

Carbon Cycle Summary

• Photosynthesis absorbs CO₂ from the atmosphere.
• Cellular respiration releases CO₂.
• Burning fossil fuels releases stored carbon.
• Forest fires release CO₂.
• Decomposition releases CO₂.
• Oceans absorb CO₂ and store in sediments.