B8 - Photosynthesis Flashcards
Word equation for photosynthesis?
Carbon dioxide + Water –> Glucose + Oxygen
What is photosynthesis?
- Endothermic reaction
- Energy is transferred from environment to chloroplasts by light
What 4 factors affect the rate of photosynthesis?
- Temperature
- Light intensity
- CO2 concentration
- Amount of chlorophyll
How does temperature affect the rate of photosynthesis?
- Temperature increases = photosynthesis increases
- TOO HIGH = ENZYMES DENATURED so it decreases and stops
How does light intensity affect photosynthesis?
- Light intensity increases = photosynthesis increases
How does CO2 concentration affect photosynthesis?
- Greater concentration = greater rate
How does the amount of chlorophyll affect photosynthesis?
- More chlorophyll = greater rate
How can you measure the rate of photosynthesis? (3)
- Place plant underwater
- Measure volume of oxygen made/count bubbles
- More gas made = greater rate
RP6 - Investigating photosynthesis 6 steps
- Add pondweed to beaker filled with water
- Place beaker 10cm away from light source
- Turn light on and leave pondweed for 5 minutes
- Count number of bubbles produced in 1 minute
- Repeat to identify outliers and calculate average
- Repeat at 20cm, 30cm, 40cm and 50cm
What are the control variables of photosynthesis practical?
- Colour of light
- Type and size of pondweed
- Temperature of water
Why do you leave the pondweed 5 minutes after the lamp has been turned on before counting bubbles?
- Gives pondweed time to acclimate
Why do you use an LED bulb when investigating the rate of photosynthesis?
- It does not heat up and raise the temperature of the water
Why might sodium hydrogen carbonate be added to the water?
- Ensure there is excess carbon dioxide and this isn’t a limiting factor
What is the dependent variable when investigating photosynthesis?
- The bubbles of gas that are produced through photosynthesis as oxygen gas
Why would the discs of pondweed in a beaker rise to the surface?
- They have made oxygen which causes them to float
What cell part is needed for photosynthesis to take place?
Chloroplast
What 5 things is glucose used for in a plant and why are they useful?
- Respiration
- Make starch - storage
- Make fats or oils - storage
- Make cellulose - strengthen cell wall
- Make amino acids - protein synthesis
How do plants make proteins?
- Amino acids made from glucose and plants combine these with nitrate ions absorbed from the soil to make proteins
How can you test a plant for starch?
- Boil in ethanol to destroy waxy cuticle + remove colour
- Add iodine to leaf(blue black change in colour)
