photosynthesis Flashcards
(20 cards)
Photosynthesis
Photosynthesis is the process by which cells synthesise organic compound (ex. glucose) from inorganic molecules (CO2 and H2O) in the presence of sunlight
Photosynthesis equation
carbon dioxide + water = (light and chlorophyll) = Glucose + oxygen + water
chemical energy created
Photsynthetic organisms use the light energy from the sun to create chemical energy (ATP). This energy can be used directly or used to synthesise organic compounds (ex. glucose)
relationship of Photosynthesis and cell respiration
1)Photosynthesis in chloroplasts (light energy)
2) Oxygen in organic compounds
3) cell respiration in mitochondria (cellular energy)
4) carbon dioxide and water back to photosynthesis
Electromagnetic spectrum
range of all possible frequencies of electromagnetic radiation
Colours of the visible spectrum
red, orange, yellow, green, blue, indigo, violet (700nm - 400nm)
Chlorophyll
Chlorophyll is a green pigment found in photosynthetic organisms that is responsible for light absorption.
When it absorbs light it releases electrons which are used to synthesise ATP
Chlorophyll reflect and absorption colours
Absorbs most strongly: Blue and red
Reflects most strongly: green
Pigments
Pigments absorb light as a source of energy for photosynthesis
Photosynthesis two step process:
1) Light dependant reactions:
- Light is absorbed by chlorophyll, which results in the production of ATP (chemical energy)
- Light is also absorbed by water, which is split (photolysis) to produce oxygen and hydrogen
- The hydrogen and ATP are used in the light independent reactions, the oxygen is released from stomata as a waste product
2) Light independent reactions:
- ATP and hydrogen (carried by NADPH) are transferred to the site of the light independent reactions
- The hydrogen is combined with carbon dioxide to form complex organic compounds (e.g. carbohydrates, amino acids, etc.)
- The ATP provides the required energy to power these anabolic reactions and fix the carbon molecules together
Pigment examples
Chlorophylls
Xanthophyll
Carontenes
Chromatography
An experimental technique by which mixtures can be separated
law of limiting factors
when a chemical process depends on more than one essential condition being favourable, the rate of reaction will be limited by the factor that is nearest its minimum value.
photosynthesis dependant on:
Temperature
Light intensity
Carbon dioxide concentration
Temperature
- Photosynthesis is controlled by enzymes, which are sensitive to temperature fluctuations
- As temperature increases reaction rate will increase, as reactants have greater kinetic energy and more collisions result
- Above a certain temperature the rate of photosynthesis will decrease as essential enzymes begin to denature
Light Intensity
- Light is absorbed by chlorophyll, which convert the radiant energy into chemical energy (ATP)
- As light intensity increases reaction rate will increase, as more chlorophyll are being photo-activated
- At a certain light intensity photosynthetic rate will plateau, as all available chlorophyll are saturated with light
- Different wavelengths of light will have different effects on the rate of photosynthesis (e.g. green light is reflected)
Carbon dioxide concentration
- Carbon dioxide is involved in the fixation of carbon atoms to form organic molecules
- As carbon dioxide concentration increases reaction rate will increase, as more organic molecules are being produced
- At a certain concentration of CO2 photosynthetic rate will plateau, as the enzymes responsible for carbon fixation are saturated
Measuring CO2 uptake
Carbon dioxide uptake can be measured by placing leaf tissue in an enclosed space with water
Increased uptake of CO2 by the plant will lower the concentration in solution and increase the alkalinity
Measuring O2 Production
Oxygen production can be measured by submerging a plant in an enclosed water-filled space attached to a sealed gas syringe
Measuring Biomass
