Mrs. Kuntz: Chapter 6 and 7 (67...)

biofuels

renewable resources,

oils, gases, and alcohols made from plants and other organic materials not derived from fossilized matter

corn and other food crops rich in oil, starches, and sugars

what can be easily converted to biofuels?

because they contain a higher proportion of cellulose

why can making biofuels from other types of plant matter be more expensive?

because it is a tough, insoluble carbohydrate that is hard to break down

why is breaking down the cellulose expensive?

fossil fuels

nonrenewable resources that consist mainly of molecules originally assembled by ancient plants

coal, gas, oil

examples of fossil fuels:

recently living plants

biofuels--and foods-- consist mainly of molecules originally assembled by _________

sunlight

the energy that plants store in organic molecules comes from ________

energy, organic molecules

photosynthesis is the process in which plants capture _____ from the sun and store it in ________

because the energy of sunlight cannot directly power energy-requiring metabolic reactions

why must the energy of sunlight be converted to the energy of chemical bonds first?

chemical, stored

unlike light, ______ energy can power the reactions of life, and it can be _____ for later use

photoautotrophs

organisms that make their own food by harvesting energy directly from the sun

carbon,

inorganic,

carbon dioxide

all organisms need _____ to build the molecules of life; autotrophs obtain it from ______ molecules such as _______

photosynthesis

a metabolic pathway that uses light to drive the assembly of carbohydrates from carbon dioxide and water

-stored as polysaccharides for later use

-remodeled into other compounds

-broken down to release energy held in their bonds

how can sugars be used?

photoheterotroph

organism that obtains both energy and carbon by breaking down organic compounds (that were assembled by other organisms)

photosynthesizers

humans and almost all other heterotrophs obtain carbon and energy from inorganic molecules originally assembled by _______.

CO2+H2O+Sunlight E --------> C6H12O6 + O2

the equation for photosynthesis:

light-dependent reactions

first stage of photosynthesis that collectively converts light energy to chemical energy of ATP

only during day

when do light-dependent reactions occur?

thylakoid membrane

where do light reactions occur?

substrates: ADP, NADP+, H2O, Energy

Products: ATP, NADPH, O2

what are the substrates and products of light-dependent reactions?

light-independent reactions

carbon-fixing second stage of photosynthesis; collectively assembles sugars from carbon dioxide and water

occur during day and night

when do light independent reactions occur?

in stroma

where do light independent reactions occur?

substrates: ATP, NADPH, CO2

products: ADP, NADP+, sugars

what are the substrates and products of light independent reactions

Calvin-Benson Cycle

what is another name for independent-light reaction?

NADPH, ATP

light-independent reactions run on energy delivered by ______ and ______ that are formed during the light-dependent reactions

light-independent reactions and light-dependent reactions

what are the two pathways in photosynthesis?

Theodor Engelmann

in 1881, botanist _______ designed a series of experiments to test his hypothesis that the color of light affects the rate of photosynthesis

electromagnetic radiation (light)

a type of energy that moves through space in waves

wavelength

distance between the crests of two successive waves (measured in nanometers)

380 and 750 nm

visible light travels in wavelengths between _______

photons

light travels in waves, but it is also organized in packets of energy called _______

shorter, longer

photons with the most energy travel in ______ wavelengths; photons with the least energy travel in ______ wavelengths

pigments

what do photosynthesizers use to capture photons of visible light?

pigment

an organic molecule that selectively absorbs light of specific wavelengths

characteristic color

wavelengths of light that are not absorbed give each pigment its __________.

chlorophyll a

main photosynthetic pigment in plants; absorbs violet, red, and orange light, and it reflects GREEN light

accessory pigments

what maximizes the range of wavelengths that an organism can use for photosynthesis?

chlorophylls

plants that change color during autumn are preparing for a period of dormancy; ______ are not needed during dormancy, so they are disassembled and their components recycled

pigments

are the molecular bridge between sunlight and photosynthesis; can absorb sunlight

pigments, efficiently

a combination of _____ allows a photosynthetic cell to _________ capture the wavelengths of light most abundant in the habitat in which it evolved.

chlorophyll a&b, carotenoids, phycobilins

examples of pigments

blue and red light; the light of these colors release the most oxygen

at what colors did the oxygen-requiring bacteria gather in Engelmann's experiment? what did this mean?

photosystem

a large complex of molecules--pigments, proteins, and cofactors--embedded in thylakoid membrane

photosystem I (p700)

photosystem II (p680)

what are the two kinds of photosystems?

photolysis

splitting of water by sunlight

ATP synthase

enzyme and transport protein

transport protein

what does ATP synthase have to be before being able to be an enzyme

O2

NADPH

ATP

final products of noncyclic pathway

electron transfer phosphorylation

process in which electron flow through electron transfer chains drives ATP formation

photosytem I

the cyclic pathway only uses what photosystem?

electrons are recycled

what happens to electrons in the cyclic pathway?

because no electrons are incorporated (they're recycled)

why is NADPH not created in the cyclic pathway?

ATP

products of cyclic pathway

Calvin-benson cycle

cyclic carbon-fixing pathway that builds sugar from carbon dioxide; light independent reactions of photosynthesis

carbon fixation

process in which carbon from an inorganic source such as carbon dioxide gets incorporated (fixed) into an organic molecule

when the enzyme rubisco fixes carbon by attaching CO2 to a five-carbon compound called RuBP

when does the reactions of the Calvin-benson cycle begin?

rubisco

ribulose diphosphate carboxylase; carbon fixing enzyme of the Calvin benson cycle

it splits right away into two three-carbon molecules of PGA (phosphoglycerate)

the six-carbon intermediate that forms by rubisco attacking CO2 to RuPB is unstable so what does it do?

PGA gets a phosphate group from ATP, plus hydrogen and electrons from NADPH

how does PGAL form from PGA?

PGAL

a three-carbon simple sugar with a phosphate group and a product of the Calvin-Benson cycle

RuBP (ribulose bisphosphate)

most of the PGAL produced in the Calvin-Benson cycle is used to regenerate what?

stomata

adjustable openings that allow gas exchange

around 6 times

how many times does the Calvin-benson cycle go around to produce glucose?

C3 pathway

another name for Calvin benson cycle

C3 plants

-only C3 pathways

-cool and wet

-wheat, rice, barely, lawn grasses

photorespiration

occurs when rubisco attaches oxygen instead of carbon dioxide to RuBP

because stomata stays closed on hot, dry days to conserve water

why would photorespiration occur?

CO2

what does photorespiration produce?

substrate of the Calvin-Benson cycle

the remainder of the photorespiration pathway converts the product of this reaction to a _____

an extremely inefficient way to produce sugars

the extra steps and energy required to undergo photorespiration makes it what?

C4 plant

type of plant that minimizes photorespiration by fixing CO2 twice, in two different cells

corn, sugar cane, weeds

examples of C4 plants

CAM plants

type of C4 plant that minimizes photorespiration by fixing CO2 twice, at different times of the day

mesophyll cell, bundle-sheath cell

C4 pathway occurs in _______ while the C3 pathway (from the CO2 produced from C4) takes place in ______

C4 plants

night (stomata opens), day (stomata closed)

C4 pathway occurs at _______ while the C3 pathway (from the CO2 produced from C4) take places at ____________

CAM plants

CAM plants

-desert-like conditions

-cacti, succulents, jade plants

cellular respiration

pathway that breaks down an organic molecule to form ATP and includes an electron transfer chain

antioxidant enzymes and vitamins

mitochondria cannot detoxify free radicals, so they rely on ________ in the cell's cytoplasm to do it for them

aerobic respiration

oxygen-requiring cellular respiration; breaks down glucose and produces ATP, carbon dioxide, and water

aerobic, 36-38 ATP per glucose

is aerobic or anaerobic respiration more efficient?

O2, NADPH, ATP

final products of noncyclic pathway?

ATP

products of cyclic pathway

cyclic pathway

electrons are recycled and no electrons are incorporated to make NADPH

stroma of chloroplast

where is sugar made?

CO2, H2O, sunlight, pigments, etc.

what molecules do plants need to carry out photosynthesis?

in the photosystems embedded inside the thylakoid membrane of the chloroplast

where in plant cell is chlorophyll found?

H2O

the oxygen released during photosynthesis directly comes from _________

organic, energy and carbon

heterotrophs require organic molecules from autotrophs (directly or indirectly) for ______ molecules, which are used as ______ sources

in the thylakoid membrane

where do light-dependent reactions occur in chloroplast?

CO2

the carbon source for organisms that derive their energy from photosynthesis is __________

ribulose bisphosphate

the carbon dioxide binds to _________ in the Calvin-Benson cycle

3-phosphoglycerate (PGA)

what is the first stable compound produced from CO2 in the light-independent reactions?

photorespiration

the reaction in which the enzyme rubisco attaches oxygen instead of carbon dioxide to ribulose bisphosphate

phosphorylation

the addition of a phosphate group to an organic molecule

anaerobic

occurring in or requiring the absence of oxygen

C6H12O6 + O2 ------> CO2 + H2O + ATP

aerobic respiration equation

six-carbon sugar (glucose)

main reactant of glycolysis