2.9 Photosynthesis Flashcards
What is photosynthesis? How is it an example of energy conversion?
Photosynthesis is a chemical reaction that takes place in the chloroplast of green plant cells, where light energy is used to convert carbon dioxide and water into glucose and oxygen
Light energy is converted into chemical energy and carbon compounds. The carbon compounds produced include carbohydrates, proteins and lipids.
What are pigments? How does the structure of pigments play a role? What colors are absorbed by what colors and what are reflected? What colors do we see?
Pigments or substances which absorb light in some pigment can absorb more colors or wavelengths than others. The color they absorb depend on their structure.
A pigment that absorbs all colors appears as black
Pigment that absorbs all colors except blue appears blue due to the fact that this part of the sunlight is not being absorbed. In other words, the remaining colors are not absorbed or reflected and the color is perceived by the brain of the observer
What is the difference between absorption and action spectra? What do they show? Why do they have a similar pattern?
An action spectrum is a graph showing the rate of photosynthesis at each wavelength of light
Absorption spectrum is a graph showing the percentage of light absorbed at each wavelength by pigment or a group of pigments.
They have a similar pattern because photosynthesis can only occur in wavelengths of light that chlorophyll or the other photosynthetic pigments can absorb.
In an action and absorption spectrum where are the peaks and where are the dips? What is on the XY axis?
There are peaks between 400-500 nm and 600 to 700 nm. Between 500 to 600nm, percentage absorption and photosynthesis rate decrease.
Action
X: 400-700 wavelength (nm).
Y: 0-100 photosynthesis (% of max rate)
Absorption
X: 400-700nm wavelength (nm)
Y: % absorption
What is chlorophyl? What color does it absorb?
Chlorophyll is a chemical substance (pigment) which can absorb light and is the main photosynthetic pigment.
Chlorophyll absorbs red and blue light most effectively and reflects green light more than other colors.
How is oxygen produced in photosynthesis? Where does the energy that drives this process come from?
Oxygen is released as a waste product for the stroma. Photolysis uses light to split water molecules to release electrons needed for other stages. This reaction only happens in the light and all the oxygen generated comes from photolysis of water.
This process is driven by energy absorbed through chlorophyll
How did photosynthesis change the earths atmosphere, oceans and rock deposition?
Glaciation? rock formation? rise in oxygen?
Prokaryotes were the first organisms to perform photosynthesis. There were very little amount of oxygen in prebiotic Earth. By carrying out photosynthesis, there was a rise in oxygen concentration of the atmosphere. This was known as the great oxidation event.
The earth also experienced its first glaciation, presumably due to a reduction in the greenhouse effect.
The increase in oxygen concentrations in The Ocean caused the oxidation of dissolved iron in the water, causing it to precipitate onto the seabed. A distinctive rock formation was produced call the banded iron formation, with layers of iron oxide alternating with other minerals. Now we have abundant supplies of steel today.
There was another significant rise when many groups of multicellular organisms were evolving.
What is carbon fixation? Energy needed? From where? Endo or Exo?
Converting carbon as a gas into a solid. Energy is required in the form of ATP and hydrogen from photolysis. The reaction is endothermic.
What is the simple equation that represents the production of carbohydrates?
Why is this process endothermic?
Where does the energy come from?
Carbon dioxide + water = carbohydrate + oxygen
A chemical equation that involves putting in energy is described as endothermic.
Energy is obtained by absorbing light
What are the limiting factors of photosynthesis?
Temperature, light intensity and carbon dioxide concentration
What is paper chromatography used for? Which one is better, paper or thin layer chromotography?
How do you calculate RF value?
Paper chromatography can be used to separate photo synthetic pigments but thin layer chromatography get better results
Rf value = distance traveled by the pigment/ distance traveled by the solvent`
What is an accessory pigment?
Pigment that’s not green
What is the final product of carbon fixation?
Glucose
Which molecules from photolysis carry the energy needed to produce carbohydrates from carbon dioxide in the light independent reactions of the stroma?
ATP and H+
