Nutrition Flashcards
What is photosynthesis? (3)
- The process of making glucose from sunlight in the leaves of the plant
- Endothermic reaction where light energy is converted into chemical energy
- In the chloroplasts
What is the word equation for photosynthesis?
carbon dioxide + water –> glucose + oxygen
(light is required)
What is the equation for photosynthesis?
6CO2 + 6H20 –> C6H12O6 + 6O2
Explain the factors that affect photosynthesis (3)
- Temperature: greater = faster, however trend only continues to the optimum temperature until the enzymes begin to denature
- Light intensity: greater = faster, as the distance increases, the light intensity decreases
- Carbon dioxide concentration: greater = faster, a reactant of photosynthesis
Why do plants need magnesium? (2)
- For chlorophyll production
- Deficiency: causes leaves to turn yellow
Why do plants need nitrate? (2)
- To produce amino acids
- Deficiency: causes stunted growth and turns leaves yellow
Why do plants need potassium? (2)
- For enzymes to catalyse respiration and photosynthesis
- Deficiency: turn yellow with dead spots
Why do plants need phosphate? (2)
- To make DNA and cell membranes
- Deficiency: poor root growth, turn purple
What is the purpose of the waxy cuticle? (2)
- Helps to reduce water loss by evaporation
- Protective layer
What is the purpose of the upper epidermis? (2)
- Very thin and transparent
- To let light into the palisade mesophyll
What is the purpose of the palisade mesophyll?
It contains many chloroplasts so photosynthesis can occur easily
What is the purpose of the spongy mesophyll? (3)
- Has a lot of air spaces
- Increases surface area to volume ratio
- Allows gases to diffuse in and out of cells faster
What 2 structures does the lower epidermis contain?
- Guard cell
- Stomata
What is the purpose of a guard cell? (2)
- Kidney-shaped cells that open and close the stomata
- Dependent on water availability (e.g. lots of water = cells fill = stomata opened)
What is the purpose of stomata? (2)
- Site where gas exchange and loss of water takes place
- Opens during the day and closes at night
What do all practical investigating photosynthesis require (measuring evolution of oxygen)? (3)
- Water plants (e.g. Elodea)
- A lamp set up beside the beaker (LED will not raise the temperature of the water)
- Sodium hydrogen carbonate is added to the water to supply CO2
How to investigate the effect of light intensity? (5)
- Place pondweed in water and set up a desk lamp with a ruler
- Move lamp away by 10cm
- Leave for a few minutes for the pondweed to adapt
- Count the number of bubbles given off in a minute
- Repeat steps but with different distances
How to investigate the effect of carbon dioxide? (4)
- Place pondweed in water
- Add different concentrations of sodium hydrogen carbonate solution
- Count the number of bubbles given off in a minute
- Remember to keep other variables constant
How to investigate starch production? (7)
- Cover half of a small leaf with foil
- Put on a windowsill so light can reach it (2 days)
- Put the leaf into boiling water to kill and preserve it
- Put the leaf in a tube containing hot ethanol for ten minutes (removes chlorophyll)
- Dip the leaf in boiling water to soften it
- Put it in a petri dish with iodine solution
- Covered half would remain orange brown, other will change to blue black (photosynthesis turned the glucose into starch)
