Chapter 10 Photosynthesis Flashcards
The complex biological process that converts the energy of light into chemical energy stored in glucose and other organic molecules. Occurs in plants, algae, and some bacteria.
Photosynthesis
Autotrophs
Any organism that can synthesize reduced organic compounds from simple inorganic sources such as CO2 or CH4. Most plants and some bacteria and archaea are autotrophs. Also called primary producer. Compare with heterotroph.
Makes own food. “Self feeders”
Heterotroph
Any organism that cannot synthesize reduced organic compounds from inorganic sources and that must obtain them by eating other organisms. Some bacteria, some archaea, and virtually all fungi and animals are heterotrophs. Also called consumer. Compare with autotroph.
“Different feeders”
Chloroplast
A chlorophyll-containing organelle, bounded by a double membrane, in which photosynthesis occurs; found in plants and photosynthetic protists. Also the location of amino acid, fatty acid, purine, and pyrimidine synthesis.
thylakoids
A flattened, membrane-bound vesicle inside a plant chloroplast that functions in converting light energy to chemical energy. A stack of thylakoids is a granum.
Geranum
In chloroplasts, a stack of flattened, membrane-bound vesicles (thylakoids) where the light reactions of photosynthesis occur.
Stroma
The fluid matrix of a chloroplast in which the thylakoids are embedded. Site where the Calvin cycle reactions occur.
Pigments
Any molecule that absorbs certain wavelengths of visible light and reflects or transmits other wavelengths.
Wavelength
The distance between two successive crests in any regular wave, such as light waves, sound waves, or waves in water.
Electromagnetic spectrum
The entire range of wavelengths of radiation extending from short wavelengths (high energy) to long wavelengths (low energy). Includes gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves, and radio waves (from short to long wavelengths).
Visible light
The range of wavelengths of electromagnetic radiation that humans can see, from about 400 to 700 nanometers.
Photon
A discrete packet of light energy; a particle of light.
Absorption spectrum
The amount of light of different wavelengths absorbed by a pigment. Usually depicted as a graph of light absorbed versus wavelength. Compare with action spectrum.
Chlorophyll
Any of several closely related green pigments, found in chloroplasts and photosynthetic protists, that absorb light during photosynthesis.
Carotenoids
Any of a class of accessory pigments, found in chloroplasts, that absorb wavelengths of light not absorbed by chlorophyll; typically appear yellow, orange, or red. Includes carotenes and xanthophylls.
Action spectrum
The relative effectiveness of different wavelengths of light in driving a light-dependent process such as photosynthesis. Usually depicted as a graph of some measure of the process versus wavelength. Compare with absorption spectrum.
Fluorescene
The spontaneous emission of light from an excited electron falling back to its normal (ground) state.
Photosystem
One of two types of units, consisting of a central reaction center surrounded by antenna complexes, that is responsible for the light-dependent reactions of photosynthesis.
Antenna complex
Part of a photosystem, containing an array of chlorophyll molecules and accessory pigments, that receives energy from light and directs the energy to a central reaction center during photosynthesis.
Reaction center
Centrally located component of a photosystem containing proteins and a pair of specialized chlorophyll molecules. Is surrounded by antenna complexes and receives excited electrons from them.
Pheophytin
In photosystem II, a molecule that accepts excited electrons from a reaction center chlorophyll and passes them to an electron transport chain.
Which term describes ATP production resulting from the capture of light energy by chlorophyll?
Substrate-level phosphorylation
Dephosphorylation
Oxidative phosphorylation
Photophosphorylation
Correct. The excitation of chlorophyll by light energy initiates a chain of events that leads to ATP production.
True or false? The chemiosmotic hypothesis states that the synthesis of ATP generates a proton gradient that leads to electron flow through an electron transport chain.
True
False
false
According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?
Temperature gradient
Osmotic gradient
Electrons
Proton gradient
Correct. A proton gradient across chloroplast and mitochondrial membranes drives ATP synthesis by the enzyme ATP synthase.
proton gradient
the graduated difference in the concentration of protons across a membrane
chemiosmotic hypothesis
the proposal by Peter Mitchell that there is an indirect linkage between electron transport and ATP production
ATP sysnthesis is powered by the potential energy stored in a gradient of protons across a membrane
Which of the following particles can pass through the ATP synthase channel?
Inorganic phosphate
ATP
ADP
Protons
Correct. The channels formed by ATP synthase are specific for protons.
True or false? The region of ATP synthase that catalyzes the production of ATP from ADP and inorganic phosphate spans the chloroplast membrane.
True
False
Correct. The region of ATP synthase that catalyzes ATP production protrudes out of, but does not span, the chloroplast membrane; the region that spans the membrane is an ion channel through which protons can pass.
Open Hint for Question 3 in a new window Chloroplast membrane vesicles are equilibrated in a simple solution of pH 5. The solution is then adjusted to pH 8. Which of the following conclusions can be drawn from these experimental conditions?
The change in the solution
’
’
s pH results in a gradient across the chloroplast membranes such that there is a lower concentration of protons inside the vesicles and a higher concentration outside.
ATP will be produced because the proton gradient favors proton movement through the ATP synthase channels.
Protons will not diffuse toward the outside of the vesicles.
ATP will not be produced because there is no ADP and inorganic phosphate in the solution.
ATP will not be produced because there is no ADP and inorganic phosphate in the solution.
Correct. This statement is true; although the proton gradient is present, ADP and inorganic phosphate are required to make ATP and were not added to the reaction.
Which process produces oxygen?
Photosynthesis
Cellular respiration
Correct. Oxygen is a by-product of the photosynthetic process.
Which set of reactions uses H2O and produces O2?
The light-dependent reactions
The light-independent reactions
Correct. The light-dependent reactions use H2O and produce O2.
What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?
The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.
The light-independent reactions turn glucose, a sugar, into CO2 gas.
The light-independent reactions turn sugar into ATP for energy.
The light-independent reactions use CO2 to make ATP.
Your Answer:
The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.
Correct. CO2 is unusable until plants have “fixed” this carbon into sugar.
How does photosynthesis II obtain electrons?
by oxidizing water
When excited electrons leave photosystem II and enter the ETC, what happens?
the photosystem becomes so electronegative that enzymes can remove electrons from water, leaving protons and oxygen
Oxygenic
Referring to any process or reaction that produces oxygen. Photosynthesis in plants, algae, and cyanobacteria, which involves photosystem II, is oxygenic. Compare with anoxygenic.
“Oxygen producing”
Anoxygenic
Referring to any process or reaction that does not produce oxygen. Photosynthesis in purple sulfur and purple nonsulfur bacteria, which does not involve photosystem II, is anoxygenic. Compare with oxygenic.
Plastocyanin
A small protein that shuttles electrons from photosystem II to photosystem I during photosynthesis.
Cyclic photophosphorylation
Path of electron flow during the light-dependent reactions of photosynthesis in which photosystem I transfers excited electrons back to the electron transport chain of photosystem II, rather than to NADP+. Also called cyclic electron flow. Compare with Z scheme.
Ribulose biphosphate
A five-carbon compound that combines with CO2 in the first step of the Calvin cycle during photosynthesis.
