AP Biology Chapter 10: Photosynthesis

Photosynthesis

The conversion of light energy to chemical energy that is stored in sugars or other organic compounds: Occurs in plants, algae and certain prokaryotes

Autotroph

An organism that obtains organic food molecules without eating other organisms or substances derived from other organisms.

Heterotroph

An organism that obtains organic food molecules by eating other organisms or substances derived from them

Chlorophyll

a green pigment located within the chloroplasts of plants and algae and in the membranes of certain prokaryotes

Mesophyll

Ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis

Stoma/Stomata

A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allow gas exchange between the environment and the interior of the plant.

Stroma

The dense fluid of the chloroplasts surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water

Thylakoid

a flattened membranous sac inside of a chloroplast

Light reactions

the first of 2 major stages in photosynthesis. These reactions occur in the thylakoid membranes of the chloroplast and convert solar energy to chemical energy of ATP and NADPH, releasing oxygen in the process

Calvin Cycle

The second of 2 major stages in photosynthesis, involving fixation of atmospheric CO2 and reduction of the fixed carbon into a carbohydrate

NADP+

Nicotinamide Adenine dinucleotide phosphate, an electron acceptor that, as NADPH, temporarily stores energized electrons produces during the light reactions

Photophosphorylation

The process of generating ATP from ADP and phosphate by means of a proton-motive force generated across the thylakoid membrane of the chloroplast during the light reactions of photosynthesis

Carbon Fixation

The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism

Wavelength

the distance between crests of waves, such as those of the electromagnetic spectrum

Electromagnetic spectrum

the entire spectrium of electromagnetic radiation ranging in wavelengths from less than a nanometer to more than a kilo

Visible Light

the portion of the electromagnetic spectrum that can be detected as various colors by the human eye, ranging in wavelength from 380nm to 750nm

Photon

a quantum, or discrete quantity, or light energy that behaves as if it were a particle

Spectrophotometer

An instrument that measures the proportions of light of different wavelengths absorbed and transmitted by a pigment solution

Absorption Spectrum

the range of pigments ability to absorb various wavelengths of light; also a graph of such a range

Chlorophyll a

a photosynthetic pigment that participates directly in the light reactions, which convert solar energy to chemical energy

Cartenoids

an accessory pigment, either yellow or orange, in the chloroplasts of plants

Photosystem

a light capturing unit located in the thylakoid membrane of the chloroplast consisting of a reaction center complex surrounded by numerous light harvesting complexes

Reaction-center complex

a complex of proteins associated with a special pair of chlorophyll a molecules and a primary electron acceptor

Light-harvesting complex

A complex of proteins associated with pigment molecules that captures light energy and transfers it to reaction-center pigments in a photosystem

Primary Electron acceptor

in the thylakoid membrane of a chloroplast, a specialized molecule that shares the reaction-center complex with a pair of chlorophyll a molecules and that accepts an electron from them

Photosystem II

Found first, It has two molecules of P680 chlorophyll a at its reaction center

Photosystem I

found second, it has two molecules of P700 Chlorophyll a at its reaction center

Linear electron flow

a route of electron flow during the light reactions of photosynthesis that involves both photosystems and generates ATP, NADPH, and O2

Cyclic electron flow

a route of electron flow during the light reactions of photosynthesis that involves only photosystems I and that produces ATP but not NADPH or O2

G3P

glyceraldehyde-3-phosphate, a 3 carbon carbohydrate that is the direct product of the calvin cycle

Rubisco

the enzyme that catalyzes the first step of the calvin cycle

C3 Plants

a plant that uses the calvin cycle for the initial steps that incorporate CO2 into organic material, forming a 3-carbon compound as the first stable intermediate

Photorespiration

a metabolic pathway that consumes O2 and ATP, releases CO2 and decreases photosynthetic output

C4 Plant

a plant in which the calvin cycle is preceded by reactions that incorporate CO2 into a 4-carbon compound the end product of which supplies CO2 for the calvin cycle

Bundle-sheath cells

a type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf

Mesophyll Cells

a type of loosely arranged photosynthetic cell located between the bundle sheath and the leaf surface

Crassulacean acid metabolism or CAM

an adaption for photosynthesis in arid conditions. A plant takes up CO2 and incorporates it into a variety of organic acids at night. During the day, CO2 is released from organic acids for use in the calvin cycle

CAM plants

a plant that uses CAM, an adaption for photosynthesis in arid conditions