B14 Flashcards
What is photosynthesis?
Process that converts light energy into biochemical energy which is then used to drive the assimilation of low energy inorganic carbon into high energy organic biochemicals.
What is the photosynthesis equation?
6CO2 + 6H20 -> C6H1206 + 6O2
What are the two phases of photosynthesis?
Light phase (grana) which is a physical phase
Dark phase (stroma) which is a chemical phase
What happens in the light phase?
Light energy absorbed by pigments is funnelled to reaction centres and used to drive the production of ATP (metabolic energy) and NADPH (reducing energy). Oxygen is also formed during the light phase
What happens in the dark phase?
Uses ATP and NADPH formed in the light phase in a series of enzyme catalysed reactions to assimilate CO2 into high energy organic form
What is climate change?
Large-scale, long-term shift in the planets weather patterns or average temperatures. Earth has had tropical climates and ice ages many times in its 4.5billion years.
How much did the ice shelf reduce by?
12%
What other changing weather patterns are there?
Rainfall, storms, hurricanes, typhoons, tornados, hurricanes. These create knock on effects and unpredictable patterns
What causes greater damage by floods and rainfall?
Compounded changes in land use
What are hurricanes and cyclones?
A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and northeastern Pacific Ocean. A cyclone is a large scale air mass that rotates around a strong centre of low atmospheric pressure.
What is happening to crop yields due to climate change?
Decrease in some yields.
What factors limit photosynthesis?
Light, CO2, Temperature, mineral deficiencies, herbicides, pollutants
What does the light saturation curve show
Below compensation point is the dark respiration rate. At low PAR, photosynthesis is masked by respiration. The PAR level where CO2 uptake is equal to CO2 output is called the compensation point. During the light limitation phase, photosynthesis is limited by the light phase. At light saturation, photosynthesis is limited by the dark phase.
What is the light saturation curve for a C3 plant?
The carboxylation reaction limits photosynthesis under high light conditions. Photorespiration occurs under low CO2 levels, as stomata close and O2 is added to RuBP instead.
What happens in photoinhibition?
A decrease in photosynthesis induced by high fluxes of PAR. Caused by an excess of PAR quanta absorbed due to exposure to excess irradiance, exposure to chilling under normal radiance, exposure to conditions that decrease CO2 fixation under normal irradiance.
What follows photoinhibition?
Photo-oxidation
What is photo-oxidation?
Bleaching of photosynthetic pigments, unless there is prolonged stress resulting in photodamage, photoinhibition is reversible and there is no permanent damage to thylakoid membranes
When considering responses of plants to climate change ; what factors need to be considered?
Change in temp and climate, change in the CO2 conc, mineral availability.
In biomes what determines the distribution of vegetation?
Climate
What ecosystems have the highest productivity?
Tropical rainforest, fresh water wetland, saltwater wetland
What provide data on past climatic conditions?
Ice cores they contain CO2 bubbles which are formed as snow falls and traps air between flakes
What effects does anthropogenic activity have on climate change?
Unprecedented increases in atmospheric CO2.
In what form is CO2 available to terrestrial and aquatic plants?
CO2 to terrestrial, HCO3- to aquatic.
How does CO2 diffuse into plants?
Via stomata
