Chapter 7 (Photosynthesis: Using Light To Make Food)

Front 1

What is photosynthesis?

Back 1

process by which pants, autotrophic protists, and some bacteria use light energy to make sugars and otehr organic food molecules from CO2 and H2O

Front 2

What are heterotrophs?

Back 2

- organism that can't make its own organic food molecules and must obtain them by consuming other organisms or their organic products
- consumer or decomposer in a food chain

Front 3

What is chlorophyll?

Back 3

- green pigment located within the chloroplasts of plants, algae, and certain prokaryotes
- ______ a can participate directly in the light reactions, which converts solar energy to chemical energy

Front 4

What is mesophyll?

Back 4

- green tissue in the itnerior of a leaf
- leaf's ground tissue system
- main site of photosynthesis

Front 5

What is stomata?

Back 5

- pore surrounded by guard cells in the epidermis of a leaf
- when open, CO2 entersa leaf, and H2O, and O2 exit
- plant conserves H2O when these are closed

Front 6

What is stroma?

Back 6

- dense fluid within the chloroplast that surrounds the thylakoid membrane and is involved in the synthesis of organic molecules from CO2 and H2O
- sugars are made here by enzymes of the Calvin cycle

Front 7

What are thylakoids?

Back 7

- flattened membranous sac inside a chloroplast
- they contain chlorophyll and the molecular complexes of the light reaction of photosynthesis
- stack of them called a granum

Front 8

CO2 enters leaves trhough stomata, and H2O enters the roots and is carried to leaves through veins

Back 8

How do the reactant molecules of photosyntheis reach the chloroplasts in leaves?

Front 9

What are light reactions?

Back 9

- 1st of 2 stages in photosynthesis
- steps in which solar energy is absorbed and converted to chemical energy in the form of ATP and NADPH
- they power the the sugar-producing Calvin cycle but produce no sugar themselves

Front 10

What is NADP+?

Back 10

electron acceptor that, as NADPH, temporarily stores energized electrons produced during the light reaction

Front 11

What is the Calvin cycle?

Back 11

- 2nd of 2 stages of photosynthesis
- cyclic series of chemical reaction that occur in the stroma of a chloroplast, using the carbon in CO2 and the ATP and NADPH produced by the light reaction to make the enrgy-rich sugar molecule GBP

Front 12

What is carbon fixation?

Back 12

- incorporation of carbon from atsmpoheric CO2 into the carbon in organic compounds
- during photosynthesis in a C3 plant, carbon is fixed into a 3 carobn sugar as it enters the Calvin cycle
- In C4 and CAM plants, carbon is fixed into a 4 carbon sugar.

Front 13

ATP & NADPH

Back 13

For chloroplasts to produce sugar from carbon dioxide in the dark, what do they need?

Front 14

What is electromagnetic spectrum?

Back 14

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

Front 15

What is a wavelength?

Back 15

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

Front 16

What is photon?

Back 16

- fixed quantity of light energy
- shorter the wavelength of light, the greater the energy of a photon

Front 17

What is chlorophyll a?

Back 17

- participates directly in light reactions
- absorbs mainly blue-violet and red light
- looks blue-green because reflects mainly green light

Front 18

What is photosystem?

Back 18

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

Front 19

What is phosphorylation?

Back 19

- transfer of a phosphate group, usually from ATP, to a molecule
- nearly all cellular work depends on ATP energizing other molecules by this

Front 20

What is C3 plant?

Back 20

plant that uses the Calvin cycle for the initial steps that incorporate CO2 into the organic material, forming a 3-Carbon compound as the 1st stable intermediate

Front 21

What is photorespiration?

Back 21

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

Front 22

What is a C4 plant?

Back 22

plant that prefaces the Calvin Cycle with reaction that incorporate CO2 into 4-carbon compounds, the end product of which supplies CO2 for the Calvin Cycle

Front 23

What is a CAM plant?

Back 23

plant that uses an adaptation for photosynthesis in arid conditions in which CO2 entering open stomata during the night is converted to organic acids, which releases CO2 for the Calvin Cycle during the day, when the stomata are closed

Front 24

What is the greenhouse effect?

Back 24

warming of Earth due to the atmospheric accumulation of CO2 and certain other gases, which absorb infrared radiation and reradiate some of it back toward Earth

Front 25

What is global climate change?

Back 25

- increase in temperature and change in weather patterns all around the planet, due mostly to increasing atmosphere CO2 levels from the burning of fossil fuels
- increase in temperature is a major aspect of this

Front 26

- high in the atmosphere, radiation from the sun converts oxygen to ozone
- ozone layer absorbs potentially damaging UV radiation

Back 26

Where does the ozone layer come from? and why is it so important to life on earth?