Chapter 10 Photosynthesis

Question 1

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.

Answer 1

Photosynthesis

Question 2

Autotrophs

Answer 2

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”

Question 3

Heterotroph

Answer 3

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”

Question 4

Chloroplast

Answer 4

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.

Question 5

thylakoids

Answer 5

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.

Question 6

Geranum

Answer 6

In chloroplasts, a stack of flattened, membrane-bound vesicles (thylakoids) where the light reactions of photosynthesis occur.

Question 7

Stroma

Answer 7

The fluid matrix of a chloroplast in which the thylakoids are embedded. Site where the Calvin cycle reactions occur.

Question 8

Pigments

Answer 8

Any molecule that absorbs certain wavelengths of visible light and reflects or transmits other wavelengths.

Question 9

Wavelength

Answer 9

The distance between two successive crests in any regular wave, such as light waves, sound waves, or waves in water.

Question 10

Electromagnetic spectrum

Answer 10

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).

Question 11

Visible light

Answer 11

The range of wavelengths of electromagnetic radiation that humans can see, from about 400 to 700 nanometers.

Question 12

Photon

Answer 12

A discrete packet of light energy; a particle of light.

Question 13

Absorption spectrum

Answer 13

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.

Question 14

Chlorophyll

Answer 14

Any of several closely related green pigments, found in chloroplasts and photosynthetic protists, that absorb light during photosynthesis.

Question 15

Carotenoids

Answer 15

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.

Question 16

Action spectrum

Answer 16

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.

Question 17

Fluorescene

Answer 17

The spontaneous emission of light from an excited electron falling back to its normal (ground) state.

Question 18

Photosystem

Answer 18

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.

Question 19

Antenna complex

Answer 19

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.

Question 20

Reaction center

Answer 20

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.

Question 21

Pheophytin

Answer 21

In photosystem II, a molecule that accepts excited electrons from a reaction center chlorophyll and passes them to an electron transport chain.

Question 22

Which term describes ATP production resulting from the capture of light energy by chlorophyll?

Substrate-level phosphorylation
Dephosphorylation
Oxidative phosphorylation
Photophosphorylation

Answer 22

Correct. The excitation of chlorophyll by light energy initiates a chain of events that leads to ATP production.

Question 23

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

Answer 23

false

Question 24

According to the chemiosmotic hypothesis, what provides the energy that directly drives ATP synthesis?

Temperature gradient
Osmotic gradient
Electrons
Proton gradient

Answer 24

Correct. A proton gradient across chloroplast and mitochondrial membranes drives ATP synthesis by the enzyme ATP synthase.

Question 25

proton gradient

Answer 25

the graduated difference in the concentration of protons across a membrane

Question 26

chemiosmotic hypothesis

Answer 26

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

Question 27

Which of the following particles can pass through the ATP synthase channel? Inorganic phosphate ATP ADP Protons

Answer 27

Correct. The channels formed by ATP synthase are specific for protons.

Question 28

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

Answer 28

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.

Question 29

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.

Answer 29

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.

Question 30

Which process produces oxygen? Photosynthesis Cellular respiration

Answer 30

Correct. Oxygen is a by-product of the photosynthetic process.

Question 31

Which set of reactions uses H2O and produces O2? The light-dependent reactions The light-independent reactions

Answer 31

Correct. The light-dependent reactions use H2O and produce O2.

Question 32

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.

Answer 32

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.

Question 33

How does photosynthesis II obtain electrons?

Answer 33

by oxidizing water

Question 34

When excited electrons leave photosystem II and enter the ETC, what happens?

Answer 34

the photosystem becomes so electronegative that enzymes can remove electrons from water, leaving protons and oxygen

Question 35

Oxygenic

Answer 35

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"

Question 36

Anoxygenic

Answer 36

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.

Question 37

Plastocyanin

Answer 37

A small protein that shuttles electrons from photosystem II to photosystem I during photosynthesis.

Question 38

Cyclic photophosphorylation

Answer 38

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.

Question 39

Ribulose biphosphate

Answer 39

A five-carbon compound that combines with CO2 in the first step of the Calvin cycle during photosynthesis.