B8 : Photosynthesis

Photosynthesis

The process by which plants synthesize glucose using light energy from the Sun, converting light energy into chemical energy.

Location of Photosynthesis

Within chloroplasts in leaf palisade cells, containing chlorophyll that absorbs light energy.

Equations for Photosynthesis (Word)

Carbon dioxide + water → glucose + oxygen

Equations for Photosynthesis (Symbol)

6CO2 + 6H2O → C6H12O6 + 6O2

Endothermic or Exothermic Reaction

Photosynthesis is endothermic, transferring energy from the environment to chloroplasts by light.

Showing Plant Gives Off Oxygen

Using a water plant (e.g., Elodea) to collect gas bubbles produced during photosynthesis, which relight a glowing splint due to the presence of oxygen.

Leaf Adaptations for Photosynthesis

Broad and thin leaves maximize surface area and minimize diffusion distance, chlorophyll traps light energy, veins transport water and remove products, air spaces allow gas exchange, and guard cells control stomata opening.

Factors Affecting Photosynthesis

Temperature, light intensity, carbon dioxide concentration, and amount of chlorophyll.

Temperature Effect on Photosynthesis

Increasing temperature increases the rate until enzymes become denatured, decreasing the rate.

Light Intensity Effect on Photosynthesis

Increasing light intensity increases the rate until another factor becomes limiting.

Carbon Dioxide Effect on Photosynthesis

Increasing carbon dioxide concentration increases the rate until another factor becomes limiting, as CO2 is required for glucose production.

Chlorophyll Effect on Photosynthesis

Decreasing chlorophyll decreases the rate as it's required to absorb light energy.

Limiting Factor

An environmental factor restricting the rate of photosynthesis, e.g., light intensity.

Calculating Photosynthesis Rate

Using a bubble potometer apparatus to measure oxygen production, where the distance moved by the bubble is used to calculate the volume of oxygen produced.

Farmers' Use of Limiting Factors

Controlling temperature, light intensity, and CO2 concentration to achieve the fastest rate of photosynthesis, leading to a greater yield.

Inverse Square Law

Describes the relationship between the distance of a light source from a plant and light intensity, stating that light intensity is inversely proportional to the square of the distance.

Uses of Glucose Produced

Respiration, starch for storage, cellulose for strength, amino acid and protein synthesis, and lipids for energy storage in seeds.