Chapter 7 Terms

Question 1

Photosynthesis

Answer 1

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

Question 2

Autotroph

Answer 2

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 autorophs

Question 3

Producer

Answer 3

An organism that makes organic food molecules from CO2, H2O, and other inorganic raw materials: a plant, alga, or autotrophic prokaryote

Question 4

Photoautotroph

Answer 4

An organism that obtains energy from sunlight and carbon from organic sources

Question 5

Chlorophyll

Answer 5

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

Question 6

Mesophyll

Answer 6

The green tissue in the interior of a leaf; a leaf’s ground tissue system; the main site of photosynthesis

Question 7

Stoma (Stomata - plural)

Answer 7

A pore 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

Question 8

Stroma

Answer 8

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

Question 9

Thylakoid

Answer 9

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

Question 10

Granum (Grana - plural)

Answer 10

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

Question 11

Light Reactions

Answer 11

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

Question 12

Calvin Cycle

Answer 12

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

Question 13

Carbon Fixation

Answer 13

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

Question 14

Electromagnetic Spectrum

Answer 14

The entire spectrum of radiation ranging in wavelength from less than a nanometer to more than a kilometer

Question 15

Wavelength

Answer 15

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

Question 16

Photon

Answer 16

A fixed quantity of light energy. The shorter the wavelength of light, the greater the energy of a photon

Question 17

Photosystem

Answer 17

A light-capturing unit of a chloroplast’s thylakoid membrane, consisting of a reaction center complex surrounded by numerous light-harvesting complexes

Question 18

Reaction Center Complex

Answer 18

In a photosystem in a chloroplast, the chlorophyll a molecules and the primary electron acceptor that trigger the light reactions of photosynthesis. The chlorophyll donates an electron excited by light energy to the primary electron acceptor, which passes an electron to an electron transport chain

Question 19

Photophosphorylation

Answer 19

The production of ATP by chemiosmosis during the light reactions of photosynthesis

Question 20

C3 Plants

Answer 20

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

Question 21

Photorespiration

Answer 21

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

Question 22

C4 Plants

Answer 22

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

Question 23

CAM Plants

Answer 23

A plant that uses an adaption 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