AQA Biology GCSE Topic 4: Bioenergetics

Flashcards for AQA Biology GCSE Topic 4: Bioenergetics, covering photosynthesis, respiration, and metabolism.

Photosynthesis

The process by which plants make glucose from sunlight; an endothermic reaction where energy is transferred from the environment to chloroplasts by light.

Carbon dioxide chemical symbol

CO2

Water chemical symbol

H2O

Oxygen chemical symbol

O2

Glucose chemical symbol

C6H12O6

Effect of Temperature on Photosynthesis

As temperature increases, the rate of photosynthesis increases until enzymes denature.

Effect of Light Intensity on Photosynthesis

The higher the light intensity, the faster the rate of photosynthesis (for most plants).

Effect of Carbon Dioxide Concentration on Photosynthesis

As carbon dioxide concentration increases, the rate of photosynthesis increases.

Chlorophyll

A pigment in the leaf that converts light energy to food for the plant; essential for photosynthesis.

Limiting Factor

An environmental condition that restricts the rate of photosynthesis, even with increases in other factors.

Inverse Proportion

Describes a relationship where one factor increases while another decreases.

Inverse Square Law

Light intensity is inversely proportional to the square of the distance light intensity ∝ 1/distance2

Uses of Glucose from Photosynthesis

For respiration, converted into insoluble starch for storage, to produce fat/oil for storage, to produce cellulose for cell walls, and combined with nitrates to form amino acids for proteins.

Respiration

The process of transferring energy from glucose so living processes can occur; occurs in every cell; exothermic.

Aerobic Respiration

Respiration using oxygen; yields the most energy; reactions occur in the mitochondria.

Anaerobic Respiration

Respiration without oxygen; does not yield as much energy; used as a last resort.

Anaerobic Respiration in Animals

Glucose (C6H12O6) ---> Lactic acid

Anaerobic Respiration in Plant and Yeast Cells (Fermentation)

Glucose (C6H12O6) ---> Ethanol + Carbon dioxide (CO2)

Oxygen Debt

The amount of extra oxygen the body needs after exercise to react with accumulated lactic acid and remove it from the cells

Metabolism

The sum of all reactions in a cell or the body; controlled by enzymes.