Chapter 7 Flashcards
greenhouse effect
the warming of the atmosphere caused by CO2, CH4, and other gases that absorb infrared radiation and slow its escape from Earth’s surface.
chlorophyll
A green pigment located within the chloroplasts of plants, algae, and certain prokaryotes. Chlorophyll a can participate directly in the light reactions, which convert solar energy to chemical energy.
granum
(plural, grana) a stack of hollow disks formed of the thylakoid membrane in a chloroplast. Grana are the sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis.
photon
A fixed quantity of light energy. The shorter the wavelength of light, the greater the energy of a photon.
photorespiration
In a plant cell, the breakdown of a two-carbon compound produced by the Calvin cycle. The Calvin cycle produces the two-carbon compound, instead of its usual three-carbon product G3P, when leaf cells fix O2, instead of CO2. Photorespiration produces no sugar molecules or ATP.
carbon fixation
The incorporation of carbon from atmospheric CO2 into the carbon in organic compounds. During photosynthesis in a C3 plant, carbon is fixed into a three-carbon sugar as it enters the calvin cycle. C4 and CAM plants, carbon is fixed into a four-carbon sugar.
photoautotroph
an organism that obtains energy from sunlight and carbon from CO2 by photosynthesis.
stoma
(plural, stomata) A pure surrounded by guard cells in the epidermis of a leaf. When stomata are open, CO2 enters a leaf, and water and O2 exit. A plant conserves water when its stomata are closed.
photosynthesis
The process by which plants, autotrophic protists, and some bacteria use light energy to make sugars and other organic food molecules from carbon dioxide and water.
mesophyll
the green tissue in the interior of a leaf; a leaf’s ground tissue system; the main site of photosynthesis.
light-dependent reactions
The first of two stages in photosynthesis; the steps in which solar energy is absorbed and converted to chemical energy in the form of ATP and NADPH. The light reactions power the sugar-producing Calvin cycle but produce no sugar themselves.
C4 plant
A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into four-carbon compounds, the end product of which supplies CO2 for the Calvin Cycle.
electromagnetic spectrum
the entire spectrum of radiation ranging in wavelength from less than a nanometer to more than a kilometer.
stroma
the fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water; Sugars are made in the stroma by the enzymes of the Calvin cycle.
thylakoid
One of a number of disk-shaped membranous sacs inside a chloroplast. thylakoid membranes contain chlorophyll and the enzymes of the light reactions of photosynthesis. A stack of thylakoids is called a granum.
autotroph
an organism that makes its own food (often by photosynthesis), thereby sustaining itself without eating other organisms or their molecules. Plants, algae, and numerous bacteria are autotrophs.
wavelength
the distance between crests of adjacent waves, such as those of the electromagnetic spectrum.
Calvin cycle/ reactions
The second of two stages of photosynthesis a cyclic series of chemical reactions that occur in the stroma of a chloroplast, using the carbon in CO2 and the ATP and NADPH produced by the light reactions to make the energy-rich sugar molecule G3P.
CAM plant
A plant that uses an adaptation for photosynthesis in arid conditions in which carbon dioxide entering open stomata during the night is converted to organic acids, which release CO2 for the Calvin cycle during the day, when the stomata are closed.
photophosphorylation
the production of ATP by chemiosmosis during the light reactions of photosynthesis.
photosystem
a light-capturing unit of a chloroplast’s thylakoid membrane, consisting of a reaction center complex surrounded by numerous light-harvesting complexes.
producer
An organism that makes organic food molecules from CO2, H2O, and other inorganic raw materials: a plant, alga, or autotrophic bacterium.
C3 plant
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbin compound as the first stable intermediate.
global climate change
Increase in temperature and change in weather patterns all around the planet, due mostly to increasing atmospheric CO2 levels from the burning of fossil fuels. The increase in temperature, called global warming, is a major aspect of global climate change.
