Photosynthesis- Seneca Flashcards
What type of reaction is photosynthesis?
Endothermic ( requires energy ) - source of energy is sunlight which is trapped by the CHEMICAL chlorophyll in the chloroplasts.
Photosynthesis symbol equation.
6CO2 + 6H2O –> C6H12O6 + 6O2
Temperature affecting rate of photosynthesis.
Increasing temp increases rate of photosynthesis as more energy is provided - if temp increased above 45 oC enzymes that catalyse the reaction denature, as a result rate drops sharply until reaction can no longer continue.
Chlorophyll concentration affecting photosynthesis.
High chlorophyll concentration gives a high rate of photosynthesis.
Concentration of carbon dioxide affect on photosynthesis.
Increasing CO2 concentration increase rate as there will be more reactant to the reaction, until above a certain threshold, rate of photosynthesis can no longer increase due to a limiting factor e.gm light intensify. Above a certain threshold stops being a limiting factor itself.
Light intensity affect on rate of photosynthesis
Increasing light intensity increases rate of photosynthesis because there is more energy avaliable. However above a certain threshold there will be no further increase due to a limiting factor such as temperature. (Limiting the rate of reaction). Above a certain threshold stops being a limiting factor itself.
Conditions of enviroment affect on photosynthesis
Warm and bright - carbon dioxide usually limiting factor.
Winter - temperature usually limiting factor
Night - light intensity limiting factor
Mineral deficient soil - if grown in mineral deficient soil, plants may not have the required mineral ions / minerals to produce lots of chlorophyll –> chlorophyll concentration limiting factor
Investigating rate with light intensity
Use of aquatic plant like pond weed.
-Change distance between lamp and pond weed and count number of bubbles produced
-light intensity independent variable and number of bubbles dependent
Bubbles are oxygen as a result of photosynthesis (product)
Lack of mineral ions affect ?
Chlorophyll traps light from the sun and chlorophyll needs mineral ions to be produced. (Especially Mg2+)
How can we increase the reliability of an experiment measuring photosynthesis ?
Measuring the rate of photosynthesis multiple times per experiment.
(Increasing the reliability of an experiment can virtually always be done by repeating an experiment, collecting values, and calculating the average of the values.)
Why is measuring the rate of photosynthesis by gas bubbles slightly inaccurate ?
Respiration produces carbon dioxide, so some of the gas in the bubbles will be carbon dioxide.This reduces the validity of the experimental method. We make the assumption that all the gas in the bubbles is oxygen, even though we know it’s not. As long as we acknowledge the assumptions we make, the experiment can still give a useful indication of the rate of photosynthesis.
Why is a high rate hard to determine with gas bubbles ?
Accuracy is how close a measured value is to its true value. If the bubbles were being released very quickly, it may be difficult to accurately count how many gas bubbles were evovled.
