Table of Contents
What is photorespiration and why does it occur?
Photorespiration is a metabolic pathway that occurs in photosynthetic organisms and releases carbon dioxide, consumes oxygen, and produces no chemical energy or food. As a plant’s environment becomes hot, dry, and bright, its stomata, where carbon dioxide enters the leaf, tend to close.
What is plant photorespiration?
Photorespiration (also known as the oxidative photosynthetic carbon cycle, or C2 photosynthesis) refers to a process in plant metabolism where the enzyme RuBisCO oxygenates RuBP, wasting some of the energy produced by photosynthesis.
What would happen to a plant that is treated with a chemical that prevents electrons moving through the electron transport chain?
Q15: What would happen to a plant that is treated with a chemical that prevents electrons from moving through the electron transport chain? It could not generate an electrochemical H+ gradient across a membrane.
What are the two stages of photosynthesis?
While there are many steps behind the process of photosynthesis, it can be broken down into two major stages: light-dependent reactions and light-independent reactions.
What is true photorespiration?
Photorespiration is a process in plants in which occurs when the carbon dioxide concentration drops to a low level. Photorespiration results in a loss of carbohydrate production for plants.
What is the difference between respiration and photorespiration?
Hint: Respiration is the process in which intake of oxygen and release of carbon dioxide happen and photorespiration is the process in which the enzyme RuBisCo oxygenates RuBP by wasting the energy produced by photosynthesis. Respiration Photorespiration It is a catabolic process. It is also a catabolic process.
Do plants fix carbon?
Carbon is primarily fixed through photosynthesis, but some organisms use a process called chemosynthesis in the absence of sunlight. Organisms that grow by fixing carbon are called autotrophs, which include photoautotrophs (which use sunlight), and lithoautotrophs (which use inorganic oxidation).
What are the steps of photorespiration?
In the photorespiration pathway, 6 O2 molecules combine with 6 RuBP acceptors, making 6 3-PGA molecules and 6 phosphoglycolate molecules. The 6 phosphoglycolate molecules enter a salvage pathway, which converts them into 3 3-PGA molecules and releases 3 carbons as CO2. This makes for a total of 9 3-PGA molecules.
What are C2 plants?
The metabolic pathway for photorespiration, in which sugars are oxidized to CO2 in the light, is known as the oxidative photosynthetic carbon cycle or C2 cycle. The term oxidative photosynthetic carbon cycle (C2 cycle) is used to be consistent with the term reductive photosynthetic carbon cycle, or C3 cycle.
What happens to the energy that is released by electrons as they move through the electron transport chain?
As electrons move through the electron transport chain, they go from a higher to a lower energy level and are ultimately passed to oxygen (forming water). Energy released in the electron transport chain is captured as a proton gradient, which powers production of ATP by a membrane protein called ATP synthase.
What happens to electrons in photosynthesis?
Absorption of light excites an electron to a higher energy state, thus converting the energy of sunlight to potential chemical energy. High-energy electrons are then transferred through a series of membrane carriers, coupled to the synthesis of ATP and NADPH.
What is the final electron acceptor in photosynthesis?
photosynthesis, light reaction The final electron acceptor is NADP+, which is reduced to NADPH. NADPH generated from light reactions is used in sugar synthesis in dark reactions.
What are the 7 steps of photosynthesis?
Terms in this set (7) Step 1-Light Dependent. CO2 and H2O enter the leaf. Step 2- Light Dependent. Light hits the pigment in the membrane of a thylakoid, splitting the H2O into O2. Step 3- Light Dependent. The electrons move down to enzymes. Step 4-Light Dependent. Step 5-Light independent. Step 6-Light independent. calvin cycle.
What are the 3 main stages of photosynthesis?
The three events that occur during the process of photosynthesis are: (i) Absorption of light energy by chlorophyll. (ii) Conversion of light energy to chemical energy and splitting of water molecules into hydrogen and oxygen. (iii) Reduction of carbon dioxide to carbohydrates.
What are the key steps in the process of photosynthesis?
The two stages of photosynthesis: Photosynthesis takes place in two stages: light-dependent reactions and the Calvin cycle (light-independent reactions). Light-dependent reactions, which take place in the thylakoid membrane, use light energy to make ATP and NADPH.
What is the first reaction of photorespiration?
2-Phosphoglycolate phosphatase (PGLP, EC 3.1. 3.18) catalyzes the entry reaction of photorespiration, dephosphorylation of phosphoglycolate formed by the oxygenase activity of RUBISCO to glycolate.
What is cyclic reaction?
1. Cyclic Photophosphorylation is a process of photophosphorylation in which an electron expelled by the excited photocentre is returned back to it after passing through a series of electron carriers. ATP is formed when electrons pass Ferredoxin to PQ and from PQ to the Cytochrome system.
Which factors affect photosynthesis?
Three factors can limit the rate of photosynthesis: light intensity, carbon dioxide concentration and temperature.
What is a C3 and C4 plant?
C3 plants are defined as the plants that use the C3 pathway in the dark reaction of photosynthesis. While C4 plants are defined as the plants that use the C4 pathway during the dark reaction. The chloroplasts of these plants are dimorphic and unlike C3 plants the leaves of C4 plants possess kranz anatomy.
What is red drop?
The red drop effect is a sharp decrease in quantum yield (number of oxygen molecules released per quantum of light absorbed- this number is usually 1/8 or 12%) at wavelengths greater than 680 nm in green plants. It is called the ‘red drop’ because it occurs in the red part of the spectrum.
How does photorespiration affect photosynthesis?
Photorespiration reduces the efficiency of photosynthesis for a couple of reasons. In other words, the carbon is oxidized, which is the reverse of photosynthesis—the reduction of carbon to carbohydrate. Secondly, it is now necessary to resynthesize the ribulose bisphosphate and to reduce the phosphoglycolate.
