Terms in this set (37)
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
An organism that makes organic food molecules from CO2, H2O, and other inorganic raw materials: a plant, alga, or autotrophic prokaryote
An organism that obtains energy from sunlight and carbon from CO2 by photosynthesis
what do "self feeding" autotrophs require from the environment in order to make their own food?
light, carbon dioxide, and water
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
The green tissue in the interior of a leaf; a leaf's ground tissue system; the main site of photosynthesis
(singular is stoma) A pore surrounded by gaurd 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
The fluid of the chloroplast surrounding the thylakoid membrane; involved in the sysnthesis of organic molecules from carbon dioxide and water; sugars are made in the stroma by the enzymes of the Calvin cycle
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
(singular granum) a stack of hollow disks formed of 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
how do the reactant molecules of photosynthesis reach the chloroplasts in leaves?
CO2 enters leaves through stomata, and H2O enters the roots and is carried to leaves through veins
Photosynthesis produces 160 billion metric tons of carbohydrate each year. Where does most of the mass of this huge amount of organic matter come from?
mostly from CO2 in the air, which provides both the carbon and oxygen in carbohydrates. Water supplies only the hydrogen
Which redox process, photosynthesis or cellular respiration is endorgonic?
define light 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
define calvin cycle
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 th ATP and NADPH produced by the light reactions to make the energy rich sugar molecule G3P
define 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. In C4 and CAM plants, carbon is fixed into a four carbon sugar
For chloroplasts to produce sugar from carbon dioxide in the dark, they would need to be supplied with _______ and _____________.
ATP & NADPH
define electromagnetic spectrum
The entire spectrum of radiation ranging in wavelength from less than a nanometer to more than a kilometer
e distance between crests of adjacent waves, such as those of the electromagnetic spectrum
a fixed quantity of light energy. The shorter the wavelength of light, the greater the energy of a photon
You may hear about the proposed health benefits of "phytochemicals" found in deep orange or read fruits and vegetables. how might such chemicals benefit a cell?
as antioxidants that protect from reactive forms of oxidative molecules
A light capturing unit of a chloroplasts thylakoid membrane, consisting of a reaction center complex surrounded by numerous light harvesting complexes
define reaction center complex
In a photosystem in a chloroplast, the chlorophyll "a" molecules and the primary electron acceptor that trigger the light reactions of a photosynthesis. The chlorophyll donates an electron excited by light energy to the primary electron acceptor, which passes an electron to an electron transport chain
Compared to a solution of isolated chlorophyll, why do intact chloroplasts release less heat and fluorescence when illuminated?
In the chloroplasts, the light excited electrons are trapped by a primary electron acceptor rather than immediately giving up all their energy as heat and light
The production of ATP by chemiosmosis during thelight reactions of photosynthesis
What is the advantageof the light reactions producing NADPH and ATP on the stroma side of the thylakoid membrane?
the calvin cycle, which consumes the NADPH and ATP occurs in the stroma
to sysnthesize one glucose molecule, the Calvin cycle must turn six times, using 6 CO2, 18 ATP, and 12 NADPH. Explain why this high number of ATP and NADPH molecules is consistent with the value of glucose as an energy source
Glucose is a valuable energy source because it is ahighly reduced, storing lots of potential energy in its electrons. The more energy a molecule stores, the more energy and reducing power required to produce that molecule
Explain why a poison that inhibits an enzyme of the Calvin cycle will also inhibit the light reactions
The light reactions require ADP and NADP, which are not recycled from ATP and NADPH when the Calvin cycle stops
define C3 plants
a plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three carbon compound as the first stable intermediate
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
define C4 plants
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
define CAM plants
a plant that uses an adaptiation 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 stomata are closed
how would you expect the relative abundance of C3 versus C4 CAM species to change in geographic region where the climate becomes much hotter and drier?
C4 and CAM species would replace many of the C3 species
define 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
define global warming
a slow but steady rise in Earths surface temperature, caused by increasing concentrations of greenhouse gases (such as CO2 and CH4) in the atmosphere
Explain the greenhouse effect
Sunlight warms earths surface, which radiates heat to the atmosphere. CO2 and other greenhouse gases absorb and radiate some heat back to earth
Where does the ozone layer in the Earths atmosphere come from?
Photosynthesis releases O2. High in the atmosphere, radiation from the sun converts some of the O2 to ozone, O3