Assignment: Design a laboratory investigation to determine if increasing the concentration of carbon dioxide affects the population growth of an algae population when nutrients are not limited. Be sure you have a control.

Materials available:
2 fluorescent lights
2 two liter soda bottles
air pump
culture of diatoms or other single celled marine algae
  or freshwater algae
source of carbon dioxide (dry ice)
marine sea salts mixed as instructed if using a marine
  species of cells
culture medium supplements:
  NaH₂PO₄  at greater than 1.0 x 10 -5 M
  NaNO₃       at greater than 3.0 x 10 -4 M
  NaSiO₃ . 9H₂O  at greater than 1.0 x 10 -4 M
spectrophotometer to measure relative cell growth