Photosynthesis

• Photosynthesis is a chemical reaction that takes place inside photosynthetic organisms such as plants and algae, converting light energy into chemical energy.
• The word equation for photosynthesis is: carbon dioxide + water → glucose + oxygen.
• A graph can be drawn to show the effect of carbon dioxide concentration on the rate of photosynthesis.
• The symbol equation for photosynthesis is: 6CO2 + 6H2O → C6H12O6 + 6O2.
• As carbon dioxide concentration increases, the rate of photosynthesis increases.
• The rate of photosynthesis eventually plateaus even if CO2 concentration continues to increase due to another factor becoming limiting.
• Carbon dioxide concentration affects the rate of photosynthesis.
• Photosynthesis is important because it produces glucose which has a wide range of uses: used in respiration to release energy, converted to starch and stored, and used to make complex organic molecules which are used for growth, making up an organism’s biomass.
• Photosynthesis takes place within chloroplasts.
• Photosynthesis is an endothermic reaction that takes in energy (in the form of light).
• Chlorophyll is a pigment found in chloroplasts that absorbs light.
• The two main stages of photosynthesis are: 1) Chlorophyll absorbs light energy which is used to split water into oxygen gas (waste product) and hydrogen ions.
• Higher temperatures provide more KE for enzymes involved in photosynthesis so the rate increases as temperature rises.
• A variable that limits the rate of a particular reaction is referred to as a limiting factor.
• Carbon dioxide combines with hydrogen ions to form glucose.
• The optimum temperature for photosynthesis is usually 25°C.
• If the temperature becomes too high (around 45°C), enzymes become denatured and the rate of photosynthesis decreases.
• The rate of photosynthesis is directly proportional to light intensity, meaning as light intensity increases, the rate of photosynthesis increases.
• Another factor (temperature or CO2 concentration) becomes limiting when the rate of photosynthesis eventually plateaus even if light intensity continues to increase.
• The effect of light intensity on the rate of photosynthesis can be measured in the lab using a light meter.
• Light intensity is inversely proportional to the square of the distance from the light source, meaning as the distance increases, light intensity decreases and the rate of photosynthesis decreases.
• Temperature, light intensity, and carbon dioxide concentration are factors that affect the rate of photosynthesis.