Biological Science, Chapter 10 Photosynthesis

Front 1

absorption spectrum

Back 1

The amount of light of different wavelengths absorbed by a pigment. Usually depicted as a graph of light absorbed versus wavelength.

Front 2

action spectrum

Back 2

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.

Front 3

anoxygenic

Back 3

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.

Front 4

antenna complex

Back 4

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.

Front 5

autotroph

Back 5

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.

Front 6

bundle-sheath cell

Back 6

A type of cell found around the vascular tissue (veins) of plant leaves.

Front 7

C3 photosynthesis

Back 7

The most common form of photosynthesis in which atmospheric CO2 is used to form 3-phosphoglycerate, a three-carbon sugar.

Front 8

Calvin cycle/reactions

Back 8

In photosynthesis, the set of light-independent reactions that use NADPH and ATP formed in the light-dependent reactions to drive the fixation of atmospheric CO2 and reduction of the fixed carbon, ultimately producing sugars. Also calledcarbon fixation and light-independent reactions.

Front 9

carbon fixation

Back 9

Calvin Cycle.

Front 10

carotenoid

Back 10

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.

Front 11

chlorophyll

Back 11

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

Front 12

chloroplast

Back 12

A chlorophyll-containing organelle that is bounded by a double membrane and in which photosynthesis occurs; found in most plant and algal cells. Also the location of amino acid, fatty acid, purine, and pyrimidine synthesis.

Front 13

cyclic photophosphorylation

Back 13

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.

Front 14

electromagnetic spectrum

Back 14

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).

Front 15

ferredoxin

Back 15

In photosynthetic organisms, an iron- and sulfur-containing protein in the electron transport chain of photosystem I. Can transfer electrons to the enzyme NADP+reductase, which catalyzes formation of NADPH.

Front 16

fluorescence

Back 16

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

Front 17

glyceraldehyde-3-phosphate (G3P)

Back 17

The phosphorylated three-carbon compound formed as the result of carbon fixation in the first step of the Calvin cycle.

Front 18

granum

Back 18

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

Front 19

guard cells

Back 19

One of two specialized, crescent-shaped cells forming the border of a plant stoma. Guard cells can change shape to open or close the stoma.

Front 20

light-independent reactions

Back 20

Calvin Cycle.

Front 21

lumen

Back 21

The interior space of any hollow structure (e.g., the rough ER) or organ (e.g., the stomach).

Front 22

maladaptive

Back 22

A trait that lowers fitness.

Front 23

mesophyll cell

Back 23

A type of cell, found near the surfaces of plant leaves, that is specialized for the light-dependent reactions of photosynthesis.

Front 24

NAD+/NADH

Back 24

Nicotinamide adenine dinucleotide exists in two forms, an oxidized and reduced form abbreviated as NAD+ and NADH respectively. In metabolism, nicotinamide adenine dinucleotide is involved in redox reactions, carrying electrons from one reaction to another.

Front 25

nicotinamide adenine dinucleotide phosphate (NADP+/NADPH)

Back 25

Oxidized and reduced forms, respectively, of nicotinamide adenine dinucleotide phosphate. A nonprotein electron carrier that is reduced during the light-dependent reactions in photosynthesis and extensively used in biosynthetic reactions.

Front 26

noncyclic electron flow

Back 26

Z scheme.

Front 27

oxygenic

Back 27

Referring to any process or reaction that produces oxygen. Photosynthesis in plants, algae, and cyanobacteria, which involves photosystem II, is oxygenic.

Front 28

PEP carboxylase

Back 28

An enzyme that catalyzes addition of CO2 to phosphoenol pyruvate, a three-carbon compound, forming a four-carbon organic acid. Found in mesophyll cells of plants that perform C4 photosynthesis.

Front 29

pheophytin

Back 29

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

Front 30

photon

Back 30

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

Front 31

photophosphorylation

Back 31

Production of ATP molecules using the energy released as light-excited electrons flow through an electron transport chain during photosynthesis. Involves generation of a proton-motive force during electron transport and its use to drive ATP synthesis.

Front 32

photorespiration

Back 32

A series of light-driven chemical reactions that consumes oxygen and releases carbon dioxide, basically reversing photosynthesis. Usually occurs when there are high O2 and low CO2 concentrations inside plant cells, often in bright, hot, dry environments when stomata must be kept closed.

Front 33

photosynthesis

Back 33

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.

Front 34

photosystem

Back 34

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.

Front 35

photosystem I

Back 35

A photosystem that contains a pair of P700 chlorophyll molecules and uses absorbed light energy to produce NADPH.

Front 36

photosystem II

Back 36

A photosystem that contains a pair of P680 chlorophyll molecules and uses absorbed light energy to split water into protons and oxygen and to produce ATP.

Front 37

pigment

Back 37

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

Front 38

plastocyanin

Back 38

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

Front 39

plastoquinone

Back 39

A nonprotein electron carrier in the chloroplast electron transport chain. Receives excited electrons from pheophytin and passes them to more electronegative molecules in the chain. Also carries protons to the lumen side of the thylakoid membrane, generating a proton-motive force.

Front 40

reaction center

Back 40

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.

Front 41

ribulose biphosphate (RuBP)

Back 41

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

Front 42

rubisco

Back 42

The enzyme that catalyzes the first step of the Calvin cycle during photosynthesis: the addition of a molecule of CO2 to ribulose bisphosphate.

Front 43

starch

Back 43

A mixture of two storage polysaccharides, amylose and amylopectin, both formed from a-glucose monomers. Amylopectin is branched, and amylose is unbranched. The major form of stored carbohydrate in plants.

Front 44

stoma

Back 44

Generally, a pore or opening. In plants, a microscopic pore on the surface of a leaf or stem through which gas exchange occurs.

Front 45

stroma

Back 45

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

Front 46

sucrose

Back 46

A disaccharide formed from glucose and fructose. One of the two main products of photosynthesis.

Front 47

thylakoid

Back 47

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.

Front 48

vascular tissue

Back 48

In plants, any tissue that is involved in conducting water or solutes from one part of a plant to another.

Front 49

visible light

Back 49

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

Front 50

wavelength

Back 50

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

Front 51

Z scheme

Back 51

Path of electron flow in which electrons pass from photosystem II to photosystem I and ultimately to NADP+ during the light-dependent reactions of photosynthesis.