The process that converts solar energy into chemical energy 

Nourishes the entire living world, whether directly or indirectly 

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Sustain themselves without eating anything derived from other organisms 

Are the producers of the biosphere, producing organic molecules from CO₂and other inorganic molecules 

Almost all plants are photoautotrophs, which use the energy from sunlight to make organic molecules from CO₂ and H₂O

Obtain their organic material from other organisms 

Are the consumers of the biosphere

Most depend on photoautotrophs for food and O2

The green pigment within chloroplasts 

Absorbs light energy 

The inner tissue of the leaf

Where most chloroplasts are found 

Typical meophyll has 30-40 chloroplasts [image]

Connected sacs in the chloroplast

Transform light enerfy t chemical energy of ATP and NADPH

Stacked in columns called grana

Where the chlorophyll be yo

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The section of photosyntheis during which:

H2O is split

O2 is released 

NADP+ is reduced to NADPH 

ATP and ADP are gnerated via photophosphorylation 

Calvin Cycle 

Forms sugars from CO2

Begins with carbon fixation,incorporating CO2 into organic molecules 

Uses ATP and NADPH

Has 3 cycles:

-Carbon fixation (catalyzed by rubisco)

-Reduction 

Regeneration of the CO2 acceptor (RuBP)

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Distance between the crests and waves 

Determines the type of electromagnetic energy 

Longer wavelengths=low energy concentrations 

Consists of wavelengths that produce colors we can see [image]

Frequency and wavelength are inverse

Substances that absorb visible light 

Different pigments absorb different wavelengths 

Wavelengths that are not absorbed are reflected or refracted 

 When a pigment absorbs light, it goes from a ground state to an excited state which is unstable 

When excited electrons fall back to the ground state, photons are given off 

Measures a pigments ability to absorb various wavelengths 

Sends light through pigments and detects the light thta passes through

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The incorporation of CO2 into organic molecules 

The beginning stage of the Calvin Cycle 

A specific form of chlorophyll that absorbs most energy from wavelengths of violet-blue and orange-red light 

Is the main photosynthetic pigment, suggesting that photosynthesis occurs best in violet-blue and orange-red light

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Functional and structural units of protein complexes involved in photosynthesis that carry out the primary photochemistry of photosynthesis 

Consists of a reaction center complex- a type of protein complex surrounded by light-harvesting complexes 

Photosystem II (PS II)

The first of two photosystems to function and is best at absorbing a wavelength of 680 nm

The reaction-center chlorophyll a of PSII is called P680

The second of two photosystems to operate in light reactions

Absorbs best at wavelengths of 700 nm 

The reaction-center chlorophyll a of PSI is called P700

One of the two possible electron routes during the light reactions

Is the primary pathway, involves both photosystems, and produces ATP and NADPH using light energy

Process:

A photon hits a pigment, its energy is passed among pigment molecules until it excites P680

An excited electron from P680 is transferred to the primary electron acceptor 

P680+(P680 missing an electron) is a very strong oxidizing agent 

H2O is split by enzymes, and the electrons are transferred from the hydrogen atoms to P680+, thus reducing it to P680 (O2 is released as a by-product) 

Each electron "falls" down an electron transport chain from the primary acceptor of PS I to PS II

Energy released by the fall drives the creation of a proton gradient across the thylakoid membrane 

Diffusion of H+ across the membrane drives ATP synthesis 

In PS I, transferred energy excites P700, which loses an electron to an electron acceptor 

P700+ accepts an electron passed down from PS II via the electron transport chain 

Each electron "falls" down an electron transport chain from the primary electron acceptor of PS I to the protein ferredoxin

The electrons are then transferred to NADP+ and reduce it to NADPH 

The electrons of NADPH are available for the reactions of the Callvin Cycle [image]

The electron route option other than linear electron flow 

Uses only PS I and produces ATP, but not NADPH 

Generates surplus ATP, satisfying the higher demand in the Calvin Cycle

Thought to have eveolved before linear electron flow 

May protect cells from light-induced damage[image]

Chloroplasts and mitochondria both generate ATP by chemiosmosis, but yse different sources of energy

Mitochondria transfer chemical energy from food to ATP; chloroplasts transform light energy into the chemical energy of ATP 

Spatial orginization of chemiosmosis differs between chloroplasts and mitochondria, but also shows similarities:

In mitochondria, protons are pumped to the intermembrane space and srive ATP synthesis as they diffuse back into the mitochondrial matrix

In chloroplasts, protons are pumped into the thylakoid space and drive ATP synthesis as they diffuse back into the stroma. ATP and NADPH are produced on the side facing the stroma, where the Calvin cycle takes place. Light reactions generate ATP and increase the potential energy of electrons by moving them from H2O to NADPH

The sugar that leaves the Calvin cycle, entering as CO2 an leaving as G3P

For net synthesis of 1 G3P, the cycle must take place three times, fixing 3 molecules of CO2

An energy production process often used by plants in dry, humind conditions, in which the stomata is closed (which conserves H2O but limits photosynthesis)

Rubisco (an enzyme onvolved in the first step of carbon fixation) adds O2 instead of CO2 in the Calvin Cycle, causing the chloroplast to consume O2 as a fuel and release CO2 without producing ATP or sugar

Limits damaging products of light reactions that build up in the absence of the Calvin Cycle  

Is a problem in many plants because on a hot, dry day it can drain as much as 50% of the carbon fixed by the Calvin cycle 

Plants that survive solely on C3 fixation (the conversion of CO2 and ribulose biphosphate (RuBP) into 3-phosphoglycerate))

Accounts for the majority of plants 

Plants that rely mostly on C4 carbon fixation 

Accounts for about 3% of terrestrial plants 

Minimize the cost of phosphorespiration by incorporating CO2 into four-carbon compounds in meohphyll cells (leaves in the middle of the cell that are specialized for photosynthesis, contain oodles of chloroplast)

Requires the enzyme PEP carboxylase (has a higher affinity for CO2 than rubisco does;it can fix CO2 even when CO2 concentrations are low)

Plants that use crassulacean acid metabolism (CAM) to fix carbon 

Open their stomata at night, incorporating CO2 into organic acid 

Stomata close during the day, and CO2 is released from organic acids and used in the Calvin Cycle