AP Biology, Chapter 10 (Photosynthesis) Flashcards

"self-feeders"

sustain themselves without eating anything derived from other organisms

producers

ultimate source of organic compounds

prokaryotes

there was very little oxygen found in Earth's atmosphere

(photosynthesis produces oxygen as a waste product)

consumers

live on compounds produced by other organisms

dependent on the process of photosynthesis for both food and oxygen

the specific sites of photosynthesis in plant cells

dense, fluid-filled area

enclosed by an envelope of two membranes

within the stroma

vast network of interconnected membranous sacs

compartment, segregated from stroma by thylakoids

separate from the stroma

this allows a proton gradient to be established

located in the thylakoid membranes

is the light-absorbing pigment that drives photosynthesis

gives plants their green color

many tiny pores

found in the exterior of the lower epidermis of a leaf

the means through which carbon dioxide enters, and oxygen/water vapor exit the leaf

the loss of water through open stomata

6 CO₂ + 6 H₂O + Light Energy -> C₆H₁₂O₆ + 6 O₂

the reverse of the one that occurs during cellular respiration

which are transferred along with hydrogen ions from water to carbon dioxide, reducing it to sugar

an endergonic process, requires energy from the sun

in the process of photosynthesis when a water molecule is split

two

occur in the thylakoid membranes

solar energy -> chemical energy

NADPH (which stores electrons), ATP, and oxygen

light energy is absorbed by chlorophyll, which drives the transfer of electrons from water to NADP⁺, forming NADPH

water is split, oxygen is released

ATP is generated, using chemiosmosis to power the addition of a phosphate group to ADP, a process called photophosphorylation

occurs in the stroma

CO₂ from the air is incorporated into organic molecules in carbon fixation

uses the fixed carbon plus NADPH and ATP from the light reactions in the formation of new sugars

CO₂ from the air is incorporated into organic molecules

the primary energy source for life on earth

electromagnetic energy that travels in rhythmic waves

the portion of light that we can see

consists of the colors red, orange, yellow, green, indigo, and violet

ie. ROY G BIV

light also behaves as though it is made up of discrete particles

each of which has a fixed quantity of energy

substances that absorb light

absorb light of different wavelengths

pigment

it absorbs violet-blue and red while transmitting and reflecting green light

this is why we see summer leaves as green

a graph plotting a pigment's light absorption as a function of wavelength

for chlorophyll, it provides clues to the effectiveness of different wavelengths for driving photosynthesis (confirmed by an action spectrum)

graphs, for photosynthesis, the effectiveness of different wavelengths of light in driving the process of photosynthesis

confirms that plants use energy from red and blue light (which is absorbed) and very little energy from green light (which is reflected)

certain groups of pigment molecules in the thylakoid membrane of chloroplasts

the groups of pigment molecules in which photons of light are absorbed in the thylakoid membrane of chloroplasts

consist of two parts: a light-harvesting complex and a reaction-center

made up of chlorophyll and carotenoid molecules of different colors of green and orange/yellow

this arrangement allows the complex to gather light effectively

accessory pigments in the thylakoid membrane

one of the molecules electrons is raised to an orbital of higher potential energy

chlorophyll is in an "excited state"

where the energy is transferred

consists of two chlorophyll a molecules that donate electrons to the second member of the reaction center

chlorophyll a molecules donate electrons to these

a molecule capable of accepting electrons and becoming reduced

the solar-powered transfer of an electron from the reaction-center chlorophyll a pair to the primary electron acceptor

conversion of light energy to chemical energy

must be replaced

splitting of water is the source of the replacement electrons

two photosystems that are important to photosynthesis

sometimes designated P700 - chlorophyll a in the reaction center of this photosystem absorbs red light of this wavelength best

P680 - absorbs light of this wavelength best

the flow of electrons through the photosystems in the thylakoid membrane

PS II absorbs light energy, exciting an electron in the P680 reaction center of two chlorophyll a molecules to a higher energy state

electron is transferred to the primary electron acceptor

reaction-center chlorophyll is oxidized and now requires an electron

enzyme splits a water molecule into two hydrogen (H+) ions, two electrons, and an oxygen atom

electrons are supplied to the P680 chlorophyll a molecules

oxygen immediately combines with another oxygen atom (forms O₂, released in atmosphere)

H⁺ released into thylakoid space

original excited electron passes from the primary electron acceptor of PS II to PS I through an electron transport chain

energy from the transfer of electrons down the electron transport chain is used to pump protons (H⁺) into the thylakoid space

H⁺ accumulates in the thylakoid space creating a gradient that is used in chemiosmosis to phosphorylate ADP to ATP

ATP used as energy in the formation of carbohydrates in Calvin cycle

light energy has also activated PS I, resulting in the donation of an electron to its primary electron acceptor

electrons donated by PS I are replaced by the electrons from PS II

the primary electron acceptor of PS I passes the excited electrons along to another electron transport chain

excited electrons are transmitted to NADP+, then reduced to NADPH

(second of the two important light reaction products)

this process removes H⁺ from the stroma, increasing the proton gradient

high energy electrons of NADPH available for use in Calvin cycle

how chloroplasts and mitochondria generate ATP