Respiration and Photosynthesis Notes

Biochemical Processes

• A biochemical process is a chemical reaction in a living thing.

• Respiration releases energy from food; photosynthesis uses energy to make food.

What is Respiration?

• Respiration is the release of energy from food.

• Aerobic respiration requires oxygen; anaerobic does not.

• Respiration equation: $food \rightarrow energy$$$food \rightarrow energy$$

Anaerobic Respiration

• In humans, anaerobic respiration produces lactic acid and some energy: $glucose \rightarrow lactic \, acid + small \, amount \, of \, energy$$$glucose \rightarrow lactic \, acid + small \, amount \, of \, energy$$

• In yeast cells, it yields alcohol, carbon dioxide, and some energy: $glucose \rightarrow alcohol + carbon \, dioxide + small \, amount \, of \, energy$$$glucose \rightarrow alcohol + carbon \, dioxide + small \, amount \, of \, energy$$

Products of Respiration

• Energy: Used by living things; more activity requires more respiration.

• Carbon dioxide: Waste product released into the air by animals; plants may use some for photosynthesis.

• Water (vapour): Waste product released into the air by plants and animals.

Factors Affecting Respiration

• Temperature: Enzymes control respiration rate, with optimal temperatures varying (37°C for humans, 20°C-30°C for plants).

• Oxygen: Essential for aerobic respiration; shortage leads to anaerobic respiration.

• Water: Lack of water slows respiration rate.

Aerobic Respiration

• Equation: $glucose + oxygen \rightarrow carbon \, dioxide + water + energy$$$glucose + oxygen \rightarrow carbon \, dioxide + water + energy$$

• Glucose is carried by blood plasma, and oxygen is carried by hemoglobin to cells.

• Aerobic respiration occurs in cytoplasm and finishes in mitochondria.