Photosynthesis Quiz

The Process of Photosynthesis and its Key Components

• Photosynthesis involves a series of reactions that use light and is an anabolic reaction.
• Light is transduced, i.e. changed from one type of energy into another, and converted into chemical energy.
• Chlorophyll and other photosensitive pigments are arranged in special photosystems that are fixed in thylakoid membranes, which make the process more efficient.
• There are two different photosystems, each linked to different electron transport chains and sensitive to light of different wavelengths: photosystem I and photosystem II.
• A photosystem consists of a reaction center molecule and an antenna complex, which is an array of proteins and chlorophyll light-harvesting molecules embedded in the thylakoid membrane.
• Different pigment molecules in the antenna complex can absorb different wavelengths, making the whole system more efficient.
• The light-dependent reactions use light to derive the synthesis of two molecules that will, in turn, drive the light-independent reactions: ATP and Reduced NADP.
• The main events in the light-dependent reactions include the excitation of electrons in chlorophyll molecules, photolysis, and the transfer of electrons to electron transport chain molecules.
• The electrons lose energy as they are passed from one carrier to the next, and one of the molecules in the cytochromes complex is a proton pump.
• Electrons in chlorophyll molecules in photosystem I are excited and escape from the molecule and pass along a second electron transport chain involving ferredoxin and NADP reductase.
• At the end of this electron transport chain, they can react with protons and NADP in the stroma of the chloroplast to form reduced NADP (NADPH).
• A photosynthetic unit is an arrangement of molecules capable of carrying out all the reactions in the light-dependent stage of photosynthesis. It is a unit of pigments, electron carriers, and ATP synthase.

The Process of Photosynthesis and its Key Components

• Photosynthesis involves a series of reactions that use light and is an anabolic reaction.
• Light is transduced, i.e. changed from one type of energy into another, and converted into chemical energy.
• Chlorophyll and other photosensitive pigments are arranged in special photosystems that are fixed in thylakoid membranes, which make the process more efficient.
• There are two different photosystems, each linked to different electron transport chains and sensitive to light of different wavelengths: photosystem I and photosystem II.
• A photosystem consists of a reaction center molecule and an antenna complex, which is an array of proteins and chlorophyll light-harvesting molecules embedded in the thylakoid membrane.
• Different pigment molecules in the antenna complex can absorb different wavelengths, making the whole system more efficient.
• The light-dependent reactions use light to derive the synthesis of two molecules that will, in turn, drive the light-independent reactions: ATP and Reduced NADP.
• The main events in the light-dependent reactions include the excitation of electrons in chlorophyll molecules, photolysis, and the transfer of electrons to electron transport chain molecules.
• The electrons lose energy as they are passed from one carrier to the next, and one of the molecules in the cytochromes complex is a proton pump.
• Electrons in chlorophyll molecules in photosystem I are excited and escape from the molecule and pass along a second electron transport chain involving ferredoxin and NADP reductase.
• At the end of this electron transport chain, they can react with protons and NADP in the stroma of the chloroplast to form reduced NADP (NADPH).
• A photosynthetic unit is an arrangement of molecules capable of carrying out all the reactions in the light-dependent stage of photosynthesis. It is a unit of pigments, electron carriers, and ATP synthase.