Chapter 7

Question 1

greenhouse effect

Answer 1

the warming of the atmosphere caused by CO2, CH4, and other gases that absorb infrared radiation and slow its escape from Earth’s surface.

Question 2

chlorophyll

Answer 2

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 3

granum

Answer 3

(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.

Question 4

photon

Answer 4

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

Question 5

photorespiration

Answer 5

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 6

carbon fixation

Answer 6

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.

Question 7

photoautotroph

Answer 7

an organism that obtains energy from sunlight and carbon from CO2 by photosynthesis.

Question 8

stoma

Answer 8

(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.

Question 9

photosynthesis

Answer 9

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 10

mesophyll

Answer 10

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

Question 11

light-dependent 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

C4 plant

Answer 12

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 13

electromagnetic spectrum

Answer 13

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

Question 14

stroma

Answer 14

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 15

thylakoid

Answer 15

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 16

autotroph

Answer 16

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.

Question 17

wavelength

Answer 17

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

Question 18

Calvin cycle/ reactions

Answer 18

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 19

CAM plant

Answer 19

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.

Question 20

photophosphorylation

Answer 20

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

Question 21

photosystem

Answer 21

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

Question 22

producer

Answer 22

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

Question 23

C3 plant

Answer 23

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.

Question 24

global climate change

Answer 24

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.