Chapter 7

Question 1

Photosynthesis

Answer 1

the process by which plants, algae, and some protists and prokaryotes convert light energy to chemical energy that is stored in sugars made from carbon dioxide and water

Question 2

Autotrophs

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 autotrophs

Question 3

Photoautotrophs

Answer 3

an organism that obtains energy from sunlight and crbon from CO2 by photosynthesis

Question 4

Heterotrophs

Answer 4

an organism that obtains organic food molecules by eating other organisms or substances derived from them; a consumer or a decomposer in a food chain.

Question 5

Chlorophyll

Answer 5

a green pigment located within the chloroplasts of plants and algae and in the membranes of certain prokaryotes. chlorophyll participates directly in the light reactions, which convert solar energy to chemical energy

Question 6

Mesophyll

Answer 6

leaf cells specialized for photosynthesis; a leafs ground tissue system

Question 7

Stomata

Answer 7

microscopic pores surrounded by guard cells in the epidermis of a leaf.when stomata are open CO2 enters a leaf and H2O and O2 exit. a plant conserves water when its stomata are closed.

Question 8

Stroma

Answer 8

the dense fluid within the chloroplast that surrounds the thylakoid membrane and is involved in the synthesis of organic molecules from carbon dioxide and water. sugars are made in the stroma by the enzymes of the of the calvin cycle.

Question 9

Thylakoids

Answer 9

a flattened membranous sac inside a chloroplast. thylakoid membranes contain chlorophyll and the molecular complexes of the light reactions of photosynthesis. a stack of thylakoids is called a granum

Question 10

Light Reactions

Answer 10

the first two stages in photosynthesis; the steps in which solar energy is absorbed and converted to the chemical energy of ATP and NADPH, releasing oxygen in the process

Question 11

NADP+

Answer 11

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

Question 12

Calvin Cycle

Answer 12

the second of two stages of photosynthesis; a cyclic series of 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 an organic compound, during photosynthesis in a C3 plant carbon is fixed into a 3-carbon sugar as it enters the calvin cycle. in C4 and CAM plants, carbon is first fixed into a 4-carbon sugar

Question 14

Wavelength

Answer 14

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

Question 15

Electromagnetic Spectrum

Answer 15

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

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 chloroplasts thylakoid membrane, consisting of a reaction-center complex surrounded by numerous light harvesting complexes

Question 18

Photorespiration

Answer 18

in a plant cell, a metabolic pathway that consumes oxygen, releases CO2, and decreases photosynthetic output. Photorespiration generally occurs on hot, dry days when stomata close O2 accumulates in the leaf, and rubisco fixes O2 rather than CO2; produces no sugar molecules or ATP

Question 19

C4 Plants

Answer 19

a plant in which the calvin cycle is preceded by reactions that incorporate CO2 into a four-carbon compound, which then supplies CO2 for the calvin cycle

Question 20

CAM Plants

Answer 20

a plat 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 stomata are closed

Question 21

Global Climate Change

Answer 21

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