30 Questions
Which photosystem generates a strong oxidizing agent?
Photosystem II
Which photosystem is capable of producing a strong reducing agent?
Photosystem I
Which photosystem is capable of producing oxygen from water?
Photosystem II
Which photosystem is capable of producing NADPH from NADP+?
Photosystem I
In the light-dependent reactions, where do protons move into during ATP synthesis?
Lumen
What is the core protein targeted by common herbicides?
PSII
What do some herbicides produce, which is toxic to human tissue?
Oxygen radicals
What is the machinery for ATP synthesis in a chloroplast similar to?
Mitochondrial enzymes
How many protons are required for the synthesis of each molecule of ATP in the light-dependent reaction?
Four
What is the main energy source for chemoautotrophs?
Inorganic molecules
What is the waste product produced by cyanobacteria during photosynthesis?
Oxygen
Which molecule has a lower affinity for its electrons and is easier to oxidize?
Sulfur in H2S
What is the primary function of photosynthesis?
Convert sunlight into chemical energy
What is the role of photoautotrophs in the production of organic compounds?
Use radiant energy to make organic compounds
During the evolution of photosynthesis, what did cyanobacteria use as an electron source?
Water
What is the origin of nutrition for heterotrophs?
Nutrients from the environment
Where are chloroplasts predominantly found?
Mesophyll cells of leaves
What is the principal pigment involved in photosynthesis?
Chlorophyll a
What is the function of carotenoids in chloroplasts?
Absorb light in the blue-green region of the spectrum
What is the source of the oxygen released during photosynthesis?
Water
What is the structure within the chloroplast where chlorophyll molecules and protein complexes for energy transduction are located?
Thylakoids
What is the function of chlorophyll in photosynthesis?
Absorb specific wavelengths of light
What is the primary location of chloroplasts within a plant cell?
Mesophyll
What is the function of photosystem II (PSII) in photosynthesis?
Boosts electrons from below the energy level of water to a midpoint
What is the role of plastocyanin (PC) in photosynthesis?
Transfers electrons from cytochrome b6f complex to PSI
What is the significance of the Z scheme in photosynthesis?
Describes the flow of electrons from H2O to NADP+ in three steps
What is the function of plastoquinol (PQH2) in photosynthesis?
Accepts two electrons from PSII and two protons from the stroma
What is the role of the antenna pigments in photosynthesis?
Absorb light, generating negatively charged free radicals
Why do plants need mobile electron carriers in photosynthesis?
Because the two photosystems are not in close proximity to each other
What is the process called when water is split into protons and molecular oxygen during photosynthesis?
Photolysis
Study Notes
Photosynthetic Metabolism Overview
- Photosynthesis occurs in two stages: light-dependent reactions and light-independent reactions.
- Each photosynthetic unit contains several hundred chlorophyll molecules, including a reaction-center chlorophyll and antenna pigments.
- Two large pigment-protein complexes called photosystems (PSII and PSI) act in series to raise electrons from H2O to NADP+.
- The flow of electrons from H2O to NADP+ is referred to as the Z scheme and occurs in three steps.
- The flow of electrons from water to PSII involves the splitting of water into protons and molecular oxygen.
- Photosystem II (PSII) boosts electrons from below the energy level of water to a midpoint, while Photosystem I (PSI) boosts electrons to a level above NADP+.
- The flow of electrons from PSII to PSI involves the absorption of light by antenna pigments, generating negatively charged free radicals.
- The flow of electrons from PSI to NADP+ (NADPH production) involves the absorption of light by the antenna pigments of LHCI and the subsequent reduction of NADP+.
- Plastoquinone (PQH2) and plastocyanin (PC) are the mobile electron carriers in plants.
- Plants need mobile electron carriers because the two photosystems are not in close proximity to each other.
- Plastoquinol (PQH2) accepts two electrons from PSII and two protons from the stroma and is soluble in the lipid bilayer, while plastocyanin (PC) is a copper-containing blue protein that transfers electrons from cytochrome b6f complex to PSI.
- The splitting of water during photosynthesis is called photolysis and requires the simultaneous loss of four electrons from two molecules of water.
Pg1-56
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