B8: Photosynthesis Flashcards
What is the equation for photosynthesis?
Carbon Dioxide + Water —> Glucose + Oxygen
6CO2 + 6H20 - C6H12O6 + 6O2
What is photosynthesis?
It involves plants using energy from light which is absorbed by the chlorophyll to change carbon dioxide and water into glucose and oxygen in the chloroplast. It is endothermic as it needs an input of energy from the environment.
What are the leaf adaptations?
- Broad to have a big surface area to absorb more light.
- Thin for a short diffusion path.
- Contain chlorophyll to absorb light.
- Have veins to bring plenty of water to the leaves through the xylem and remove the products through the phloem.
- Has air spaces.
- Guard cells open and close stomata to regulate gas exchange.
How does light intensity affect photosynthesis?
If there is more light then more photosynthesis can take place at a quicker rate.
How does temperature affect photosynthesis?
If the temperature increases then so does the rate of photosynthesis as it is controlled by enzymes. However if the temperature is too high then the enzymes denature and the rate of photosynthesis decreases.
How does carbon dioxide affect photosynthesis?
A greater carbon dioxide concentration increases the rate of photosynthesis as it is needed to make glucose. It is low during the day and highest at night but can be artificially increased in greenhouses.
What is a limiting factor?
It is an environmental condition that when in low levels, prevents any increase in the rate of a reaction such as photosynthesis.
How do chlorophyll levels affect photosynthesis?
If there is more chlorophyll in the plant then it increases the rate of photosynthesis as it is needed to absorb light. A magnesium deficiency therefore decreases the rate of photosynthesis.
How can farmers enhance conditions?
• In greenhouses, farmers enhance the conditions thinking about the limiting factors so that it is ideal conditions for photosynthesis to take place and for more growth and profits.
- Greenhouses help to trap the Sun’s heat, ventilation or heaters may also be used if too hot or cold.
- Artificial light is often supplied.
- Carbon dioxide concentration can be artificially increased.
- Enclosed in greenhouse prevents pests and disease.
Describe the method to find the photosynthesis of a pondweed.
- Cut a piece of pondweed 8-10cm long and place it in a boiling tube of sodium hydrogen carbonate solution with the cut end upwards.
- Use thermometer to measure the temperature of the boiling tube.
- Place the tube in a large beaker of water to act as a heat shield and position it 10cm away from the lamp.
- Wait until there is a steady flow of bubbles from the pondweed. Count the number of bubbles in 2 mins and record.
- Measure temperature in the boiling tube to make sure it hasn’t changed.
- Repeat steps but increase the distance between the lamp and the boiling tube by 10cm each time.
- Repeat whole investigation two more times and calculate a mean for each distance.
Use inverse square law to find the light intensity: Light Intensity = 1/distance^2
How do plants use glucose?
• Respiration - transfers energy from the glucose.
• Produce cellulose - this helps the plant make strong cell walls.
• Making amino acids - glucose is combined with nitrate ions to make amino acids which are then made into proteins.
• Stored as oil/fats - glucose is turned into lipids for storing in seeds.
• Stored as starch - glucose is converted into starch and stored in roots/stems/leaves which can later be used if photosynthesis isn’t happening for energy.
