Photosynthesis Flashcards
What is the fundamental equation of photosynthesis?
6C02 + 6H20 >{light}> C6H1206 [sugar] + 602
What is the definition of photosynthesis?
Conversion of light energy into chemical energy in the form of sugars.
Why is photosynthesis important?
Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth’s atmosphere, and supplies all of the organic compounds and most of the energy necessary for life on Earth.
What is the highest level description of photosynthesis?
In a process driven by light energy, glucose molecules (or other sugars) are constructed from water and carbon dioxide, and oxygen is released as a byproduct. The glucose molecules provide organisms with two crucial resources: energy and fixed—organic—carbon.
How did photosynthesis shape life on Earth?
Most photosynthetic organisms generate oxygen gas as a byproduct, and the advent of photosynthesis—over 333 billion years ago, in bacteria resembling modern cyanobacteria—forever changed life on Earth.
These bacteria gradually released oxygen into Earth’s oxygen-poor atmosphere, and the increase in oxygen concentration is thought to have influenced the evolution of aerobic life forms—organisms that use oxygen for cellular respiration.
What is the role of photosynthesis in climate change?
Photosynthesis fixes carbon dioxide, the most abundant greenhouse gas, into organic carbon. Preserving the existing photosynthetic organisms is essential, but unlikely to be enough to slow climate change.
What are the effects of climate change on phytoplankton (and therefore, photosynthesis)?
Ocean acidification may affect the development of calcium carbonate ‘shells’ on coccolithophores, but some studies have found that diatoms grow faster and increase photosynthesis with carbon dioxide enrichment experiments.
What are the effects of climate change on phytoplankton (and therefore, photosynthesis)?
Ocean acidification may affect the development of calcium carbonate ‘shells’ on coccolithophores, but some studies have found that diatoms grow faster and increase photosynthesis with carbon dioxide enrichment experiments. Other studies have found nutrient content and oxygen production reduced with carbon dioxide enrichment. More investigation is needed here.
What are the two main mechanisms of photosynthesis?
Light reactions and the Calvin cycle
Describe the light reactions at a high level.
The light reactions take place in the thylakoid membrane and require a continuous supply of light energy.
Chlorophylls absorb this light energy, which is converted into chemical energy through the formation of two compounds, ATP and NADPH —a reduced (electron-bearing) electron carrier. In this process, water molecules are also converted to oxygen gas.
Electrons are removed from water and passed through PSII and PSI before ending up in NADPH. This process requires light to be absorbed twice, once in each photosystem, and it makes ATP.
What are the anatomical parts of a plant involved in photosynthesis?
Plants have leaves with stomata (pores) open and let carbon dioxide diffuse into mesophyll cells, which has chloroplasts in it. Thylakoids in the chloroplasts house the chlorophyll pigments that are used in the light dependent reactions.
Describe the Calvin cycle at a high level.
The Calvin cycle takes place in the stroma and does not directly require light. Instead, the Calvin cycle uses ATP and NADPH from the light-dependent reactions to fix carbon dioxide and produce three-carbon sugars—glyceraldehyde-3-phosphate, or G3P, molecules—which join up to form glucose.
Why is fixed carbon helpful for plants?
The carbon that’s fixed and incorporated into sugars during photosynthesis can be used to build other types of organic molecules needed by cells.
What is the peak wavelength of absorption for the special pair of electrons in PS1?
700nm
What is the peak wavelength of absorption for the special pair of electrons in PS2?
680nm
