Investigating Photosynthesis

Investigating Photosynthesis

Experimenting with Photosynthesis

  • Photosynthesis can be investigated in a laboratory setting using a plant such as Elodea Canadensis.
  • In this experiment, the plant is placed in a test tube filled with water and exposed to a light source. Oxygen bubbles produced by the plant provide an estimate of the rate of photosynthesis.

Effects of Light Intensity

  • The effect of light intensity on the rate of photosynthesis can be studied using a light meter.
  • By placing the source at different distances from the plant, the intensity is altered and the effects can be observed.
  • A higher intensity usually increases the rate of photosynthesis because more energy is available for the light-dependent reactions.

Effects of Carbon Dioxide Concentration

  • The influence of carbon dioxide concentration on photosynthesis can also be explored. This is typically adjusted through the addition of sodium bicarbonate to the water.
  • A high level of carbon dioxide often boosts photosynthesis, as more of it is available for use in the Calvin Cycle.

Effects of Temperature

  • Understanding the impact of temperature on photosynthesis involves warming or cooling the water in which the plant is kept.
  • Photosynthesis rates usually increase with temperature, up to a certain point, due to the increased activity of enzymes.
  • However, very high temperatures may cause damage to the plant or enzymes involved in photosynthesis, slowing down the process or stopping it entirely.

Using a Potometer

  • A potometer is a device that can be used to measure transpiration, a factor closely linked with photosynthesis.
  • It does so by tracking the rate at which a plant absorbs water, an indicator of the rate of photosynthesis.

Considering Limiting Factors

  • When conducting these experiments, remember that photosynthesis can be limited by several factors at once. This is based on the law of the minimum, wherein the least available factor puts a cap on the process.
  • For example, adding more light will not increase photosynthesis if the plant has insufficient carbon dioxide. This principle is crucial when analysing results.

Monitoring Gas Exchange

  • The gas exchange can be tracked to provide evidence of photosynthesis.
  • When a plant photosynthesises, it absorbs carbon dioxide and releases oxygen. This can be monitored using a gas probe or sensor.
  • This data not only signals that photosynthesis is occurring, but can also give an estimate of its rate.