Limiting Factors in Photosynthesis Flashcards
(13 cards)
How can the rate of photosynthesis be directly measured?
Directly: by the production of oxygen or the uptake of carbon dioxide.
How can teh rate of photosynthesis be indirectly measured?
Indirectly: By an increase in biomass.
How can you tell if there’s a production of oxygen?
There is a release of bubbles of oxygen when aquatic plants carry out photosynthesis. When the bubbles are collected, the volume can be measured.
How can you tell if there’s an uptake of carbon dioxide?
If CO2 is absorbed from water, the pH of the water rises. Therefore, pH indicators and pH meters can monitor this.
How can you tell if there’s an increase in biomass?
If batches of plants are harvested at a series of times and the biomass of the batches is determined, the rate of increase in biomass gives an indirect mesaure of the rate of photosynthesis.
How does the concentration of CO2 affect photosynthesis?
Photosynthesis does not occur with low CO2 concentrations. At low-fairly high concentrations of CO2, the rate is positively correlated with CO2 concentration. At very high CO2 concentrations, the rate reaches a plateau.
What effects do light intensity have on photosynthesis?
At low-medium light intensities, the rate is directly proportional to light intensity. At high light intensities, the rate reaches a plateau.
What effects do temperature have on photosynthesis?
As temperature increases, the rate increases more and mroe steeply. After optimum temperature, the rate of photo. falls steeply.
What are the three main limiting factors on photosynthesis?
Light intensity, carbon dioxide concentration, and temperature.
What is the rate of photosynthesis determined by?
The rate of whichever step is proceeding most slowly at a particular time.(rate-limiting step)
What happens when there is a lack of light?
There is a shortage of the products of the light-dependent reactions (NADPH and ATP)
What happens in the Calvin cycle when there is a lack of CO2 concentrations?
This point slows down: where CO2 is fixed to produce glycerate 3-phosphate. Therefore RuBP and NADPH accumulate.
What happens when temperature fluctuates?
The enzymes that catalyze the reactions of the Calvin cycle work slowly. At high temperatures, RuBP carboxylase does not work effectively (where CO2 is fixed is much slower). IN BOTH CASES, NADPH ACCUMULATE.
