1. Which affect the rate of photosynthesis
limiting factors
Which affect the rate of photosynthesis

2. Investigation into the effects of mineral ions on plant growth
Hypothesis: Soil which is mineral ion deficient can result in lack of growth for plants. Dependant on what ion is and isn’t present, plants can wilt due to the softening of their tissues. Most importantly, chlorophyll can become non existent which means photosynthesis cannot occur and the plant dies.
Equipment:
30g Soil, 5 plant pots, 20 seeds from the same plant, fertiliser containing the specific mineral ion with 5 different concentrations (20%,30%,40%,50%,60%)
Independent variable – The concentration of fertiliser containing the mineral ion.
Dependant variable – The amount of sunflowers that grow.
Controlled variables –
Same plant pot size
Same temperature and pH of soil
Same light intensity exposed to plant
Same water content in soil
Same type of seed
Same volume of water and liquid fertiliser

3. Method:
Firstly, place 30g of soil in each plant and place 4 sunflower seeds in the soil.
Ensure that the pH and temperature of the soil is the same in each plant pot.
Place 5cm³ of water in a beaker and 5cm³ of fertiliser containing potassium at 20%. Mixing water and fertiliser in a beaker ensures that the fertiliser is well dissolved and that each plant is exposed to the same amount of solution in the same area.
Place the plant under a lamp, each of which at the same power output.
After each week record the amount of sunflower seeds grown for 4 weeks.
Repeat this method for each concentration of fertiliser.
Record results in the table below.