ap bio - photosynthesis

what is the balanced equation for photosynthesis?

6 CO2 + 6 H20 --sunlight/hv-→ C6H12O6 + 6O2

what starting information is needed to design an experiment? (what do you need to identify?)

question, blank, control, manipulated, responding, constants

used to memorize: QBC-MRC

what do you need to find/calculate in an experiment?

mean, SEM (standard deviation), claim

how will you verify your designed experiment?

multiple trials

what is % transmittance used to find?

the rate of photosynthesis

what are the two main steps in photosynthesis?

light reactions and calvin cycle

why are mesophyll cells special?

mesophyll cells are special because they store 30-40 chloroplasts and make up interior leaf tissue.

what did the use of radioisotopes tell us about the source of the released O2 in photosynthesis?

the use of radioisotopes told us that hydrogen is extracted from water and incorporated into sugar, while O2 is released with sugar as “waste product”

what is the electron carrier in photosynthesis?

NADPH

what is the location of substrate level phosphorylation?

cytoplasm / mitochondria

what is the location of oxidative phosphorylation?

mitochondria

what is the location of photophosphorylation?

chloroplasts

what is phosphorylation in any form?

a process in which a phosphate group is added to a molecule, such as a sugar or a protein

what is the source of energy in substrate-level phosphorylation?

glycolysis + pyruvate breakdown → ADP

what is the source of energy in oxidative phosphorylation?

citric acid cycle → NADH & FADH2

what is the source of energy for photophosphorylation?

light reaction → NADP+

does substrate level phosphorylation use chemiosmosis or direct transfer of phosphates using enzymes?

direct transfer of phosphates using enzymes

does oxidative phosphorylation use chemiosmosis or direct transfer of phosphates using enzymes?

chemiosmosis

does photophosphorylation use chemiosmosis or direct transfer of phosphates using enzymes?

chemiosmosis

what does carbon fixation mean?

a carbon atom is attached to an organic compound

which portion of the electromagnetic spectrum “powers” photosynthesis?

380 nm - 750 nm

what does a spectrophotometer do?

a spectrophotometer allows you to shine light of specific wavelengths at an object, then measure how much was absorbed.

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a spectrophotometer measures proportions of light of different wavelengths absorbed and transmitted by pigment solution.

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a spectrophotometer can be used to measure the absorption spectrum of a substance.

what are pigments?

substances that absorb visible light

what do chlorophyll pigments do with white light?

chlorophyll pigments absorb white light and reflect green while transmitting the spectrum.

how does beta-carotene contribute to photosynthesis?

beta-carotene contributes to photosynthesis by transmitting the light energy it absorbs to chlorophyll.

what do carotenoids do?

carotenoids absorb and capture light to be used in light reactions.

what did engelmann observe that told him which wavelengths of light result in the most photosynthesis?

he noticed that the rate of photosynthesis measured by O2 release was highest from 400-500 nm and 600-700 nm.

why do chlorophyll a and chlorophyll b appear as different colors?

chlorophyll a and b appears as different colors because they have slightly different structural differences that allow the two pigments to absorb slightly different wavelengths of the red and blue parts of the spectrum.

what is the difference between the action spectrum and the absorption spectrum?

absorption spectrum measures absorption of light by chloroplast pigments, while the action spectrum measures rate of photosynthesis measured by O2 release.

what state is an electron while in its typical orbital?

ground state

what state is an electron in when it absorbs energy and jumps to a higher energy level?

excited state

when an electron falls back to its original state, what does it release?

a photon of electromagnetic energy

do shorter wavelengths have more or less energy?

shorter wavelengths have greater amounts of energy

what is the advantage of having different pigments in the light-harvesting complex?

a variety of pigment molecules enable a photosystem to harvest light over a large surface area and a larger portion of the spectrum.

what is the movement of electrons through linear electron flow?

light → p680 chlorophyll a → primary electron acceptor → e-carrier→ cytochrome complex → e-carrier → p700 chlorophyll a → primary electron acceptor → e-carrier → NADP+ reductase → NADPH

what is the purpose of the first electron transport chain in light dependent reactions?

to produce ATP

what is the purpose of the second electron transport chain in light dependent reactions?

to produce NADPH

what are the electrons in the p680+ replaced by?

the electrons gained by the splitting of water

what are the 3 main phases of the calvin cycle?

carbon fixation, reduction, regeneration of CO2 acceptor

what is the purpose of the cyclic flow of electrons?

the purpose of the cyclic flow of electrons is to generate ATP in photosynthesis

what powers chemiosmosis in mitochondria?

high energy electrons extracted from organic molecules power chemiosmosis in mitochondria

what powers chemiosmosis in chloroplasts?

high energy electrons extracted from water power chemiosmosis in chloroplasts

which molecule is incorporated into the calvin cycle to react with ribulose biphosphate?

g3p is incorporated into the calvin cycle to react with ribulose biphosphate by atp

the atp and nadph of the calvin cycle are used to make 6 molecules of…

g3p

how many co2 must be fixed in the calvin cycle if you want to remove 1 g3p?

3

is the conversion of 3-phosphoglycerate to 1, 3, biphosphoglycerate exergonic or endergonic and why?

the conversion of 3-phosphoglycerate to 1, 3, biphosphoglycerate is exergonic because atp is added

is g3p being added to regenerate RuBP exer or endergonic and why?

g3p being added to regenerate RuBP is endergonic because G3P is broken into new RuBP molecules

what is photorespiration?

photorespiration is the process of taking in molecular oxygen and releasing CO2 from organic substances in response to light.

why is photorespiration harmful?

photorespiration is harmful because it reduces plant productivity and wastes atp and nadph

what molecules are involved in light dependent reactions?

oxygen, water, and light

what molecules are involved in the calvin cycle?

carbon dioxide and sugar

what is the purpose of light dependent reactions?

to produce atp and nadph

what is rubisco?

rubisco stands for ribulose biphosphate and is a carbon fixer.

what is oxygen compared to carbon dioxide in relation to ribisco?

oxygen is a competitive inhibitor

what is the general problem with rubisco?

it isn’t “picky” enough, so it allows oxygen to bind to its active site, which doesn’t allow sugars to be produced. the atp and nadph that was used to regenerate the RuBP is wasted.

what happens to chlorophyll a molecules in the reaction center?

chlorophyll a molecules are oxidized

how do high energy UV rays affect tissues?

high energy ultraviolet rays can harm living tissues

what powers photosynthesis?

wavelengths of light within the visible part of the light spectrum power photosynthesis

what happens when light is absorbed by leaf pigments?

electrons within each photosystem are boosted to a higher energy level, and this energy produces atp and reduces NAPH+ to NADPH.

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atp and NADPH then incorporate CO2 into organic molecules in carbon fixation.

how is DPIP affected by light?

when light strikes chloroplasts, electrons boosted to high energy levels with reduce DPIP.

visually, DPIP will change from blue to colorless.

what happens as DPIP becomes colorless?

DPIP is reduced, which results in increased light transmittance.

what are accessory pigments?

accessory pigments are pigments that aid in photosynthesis by capturing and absorbing other wavelengths of light

when given an absorption spectrum for an unknown pigment molecule, how do you determine the color of the pigment?

the lowest point of the graph is the color of the light.

what does noncyclic electron flow and chemosmosis result in?

atp, nadph, and O2

where does hydrogen split from oxygen?

thylakoid space

where do light reactions take place?

light reactions take place in the stack of thylakoids

where does the electron transport chain take place?

the electron transport chain takes place in the thylakoid membrane

where does the calvin cycle take place?

the calvin cycle takes place in the stroma

where is atp synthase located?

atp synthase is located in the thylakoid membrane

where is atp made and used?

atp is made and used in the stroma

what are the possible substrates of rubisco?

RuBP, CO2, and O2

can chloroplasts make carbohydrates in the dark?

yes, chloroplasts can make carbohydrates in the dark

what is needed to help chloroplasts make carbohydrates in the dark?

atp, nadph, and co2

nadph and atp from the light reactions are both needed…

to reduce 3-phosphoglycerate to g3p

why are plants green?

plants do not absorb green wavelengths of white light, so the green light is reflected and appears as green