B8 - Photosynthesis Flashcards
What is the word equation for photosynthesis?
Carbon dioxide + water (+light)»_space;> glucose + oxygen
What is the balanced chemical symbol equation for photosynthesis?
6CO2 + 6H2O»_space;> C6H12O6 + 6O2
Is photosynthesis an endo- or exothermic reaction?
Endothermic
What energy transfer occurs in photosynthesis?
Light energy to chemical energy
Where does photosynthesis occur in a plant cell?
Chloroplasts
What pigment are chloroplasts filled with?
Chlorophyll
What is the function of chlorophyll?
Captures light energy
What are the four factors which affect the rate of photosynthesis?
Temperature, light intensity, carbon dioxide concentration, amount of chlorophyll
Why does increasing light intensity increase the rate of photosynthesis?
Light provides the energy the plants need to photosynthesise
Why does increasing temperature increase the rate of photosynthesis?
A higher temperature increases the rate of the chemical reactions
Why does increasing the temperature too far stop photosynthesis?
The enzymes in the plant become denatured and stop working
Why does increasing the concentration of carbon dioxide increase the rate of photosynthesis?
Carbon dioxide is a raw material that is needed for photosynthesis
How can we investigate the effect of light intensity on the rate of photosynthesis?
- Place pondweed in a test tube with water
- Place a light source 10cm away from it
- Turn light source on a measure the number of bubbles produced in 1 min
- Move the light source back to 20cm and repeat
- Repeat until there is a big enough range of results to see a pattern
What can be done to stop temperature affecting the rate of photosynthesis?
Use an LED light, or place the boiling tube into a beaker of water
What is the inverse square law?
light intensity ( oc symbol) 1/d2
How does the inverse square law apply to photosynthesis?
The intensity of light is inversely proportional to the square of the distance from the light source.
What does the inverse square law mean in practice when considering how plants grow?
When the light is moved twice as far from the plant it will receive a quarter of the energy
Why can’t a commercial grower of plants just increase all three limiting factors of PHS to maximum levels to obtain optimum growth?
Light, temperature and CO2 all cost money to supply
– a balance between expenditure and income must be struck for a profit to be made.
Name three ways glucose produced in photosynthesis is used in plants.
- Respiration
- Converted into insoluble starch for storage
- To produce fat or oil for storage
- To produce cellulose, which strengthens the cell wall
- To produce amino acids for protein synthesis.
What else, other than glucose, do plants need to produce proteins?
Nitrate ions
Where are mineral ions absorbed from and through which plant organ?
From the soil, through the roots.
