Photosynthesis
What are these characteristics of? 1) When it is excited by light it loses a high-energy electron, 2) one component is Mg, 3) it has a fatty acid tail, 4) it is able to act as a reducing agent
chlorophyll
What is located inside the thylakoid membranes?
chlorophyll
NADP is an oxidizing agent that ____ electrons to become reduced during photosynthesis.
accepts
Both blue and red areas of the spectrum are the most effective for photosynthesis. Nearly all wavelengths of light are used for photosynthesis because of the presence of _______. Chlorophyll a has 2 peaks of read and blue in the spectrum.
accessory pigments
What makes up a thylakoid?
bi-lipid membrane, proteins in groups that allows plants to use light for energy with are called light harvesting antennae, chlorphyll
During photosynthesis, water is oxidized and oxygen is reduced. Water is oxidized to form oxygen gas and CO2 is reduced to form ___.
carbohydrates
Proteins are concentrated in certain areas of the membrane of the thylakoids. They are part of a system of proteins that move electrons. On of these proteins is called the "light harvesting antenna." These contain ___.
chlorophyll
We see green when we look at a leaf because ___ absorbs violet-blue and red while reflecting green light.
chlorophyll
carbon fixation
the process by which plants turn inorganic carbon (carbon dioxide) into organic compounds such as carbohydrates
A reaction cent of a chloroplast is embedded in the ___.
thylakoid
Light drives the synthesis of NADPH and ATP by energizing the two photosystems embedded in the _____ of chloroplasts.
thylakoid membranes
T/F: Visible light is a form of electromagnetic energy.
true
True or False: Not all photosynthetic organisms have leaves.
true
The cuticle is a waxy, waterproof covering that is secreted by the _____, which is the layer of cells on the upper surface of the leaf.
upper epidermis
Waxy cuticle
leaf's topmost waterproof layer
Van Niel
(Last name) Hypothesized that oxygen was released from water, not carbon dioxide
Picture of photosystem in the interior of a thylakoid.
1) Energy of photon hits pigment, 2) transfer of energy to special chlorophyll a, 3) primary e- acceptor catches it (redox), 4) isolated chlorophyll fluorescences because there is no e- acceptor, so e- drops backdown to ground state, 6) the captured light energy to chemical energy will ultimately be used from synthesis of sugar.
The thylakoid has two types of photosystems. Describe them.
1) photosystem II (PSII) - functions 1st, reaction center is P680 because the pigment is best absorbing light at wavelength of 680 nm in red part of spectrum; 2) photosystem I (PSI) - functions 2nd, reaction center is called P700 because it is most effectively absorbing light with at wavelength of 700 nm.
What is the formula for photosynthesis?
12H20 + 6CO2 + Light --> 6O2 + C6H1206 + 6H20
R. Hill
1st person to isolate and experiment with chloroplasts; light reaction -> split water and light independent reaction -> generate glucose
Thylakoid
A flattened membrane sac inside the chloroplast, used to convert light energy into chemical energy.
Explain what happens when a photon hits and electron.
A photon, carrying lots of energy, travels at the speed of light toward the e-. The photon is much smaller and when it strikes, the e- becomes excited and gains energy when excited. The farther an e- is moved from the nucleus, the more unstable it is. It stays in excited state shortly and fall back to ground state. When it does this, a photon is released.
Chloroplasts are chemical factories powered by the sun. Their thylakoids transform light energy into the chemical energy of ___ and ___.
ATP and NADPH
The main source of carbon in photosynthesis is from ____.
CO2
How do the reactant molecules of photosynthesis reach the chloroplast in leaves?
CO2 enters leaves via stomata; H2O enters through roots and travels up veins
___ can be found at ground state and excited state.
Electrons
Summarize energy during respiration.
Energy is released from sugar when e- associated with H are transported by carriers to O forming water as a by-product. The e- lose PE as they "fall" down the e- transport chain toward electronegative O, and the mitochondrion harness that energy to synthesize ATP.
Where can chloroplasts be found in the plant cell?
In the meosphyll (middle of the leaf)
What coenzyme is the electron acceptor in photosynthesis?
NADP (Nicotinamide Adenine Dinucleotide Phosphate)
Describe the calvin cycle.
Occurs in stroma; Incorporates CO2 from air into organic molecules already present in the chloroplast (carbon fixation). The fixed carbon is then reduced to carbohydrate by the addition of e-. The reducing power is provided by NADPH (source of energized e). The ATP (chemical energy) converts CO2 to carbohydrates. Sugar is made with help of NADPH and ATP produced by light reactions. Mostly occus during daylight because it is waiting on the NADPH and ATP from light reactions.
Describe the light reactions.
Occurs in thylakoids; convert solar energy to chemical energy; Light absorbed by chlorophyll drives a transfer of e- from H2O to an acceptor celled NADP+, which temporarily stored the e-. H2O is split and gives off O2. The solar power reduces NADP+ to NADPH by adding H+. ATP is also generated using chemiosmosis to power addition of a Phosphate group ADP (phosphorylation). This light energy is converted to chemical energy in the compounds: NADPH (source of energized e-) and ATP (energy currency of the cell). No sugar is produced.
Which part of the photosystem uses cyclic electron flow?
PSI
Which part of the photosystem uses non-cyclic electron flow?
PSII
Summarize energy during photosynthesis.
Photosynthesis reverses the direction of water flow. Water is split, e- are transferred along with H+ from H2O to CO2, reducing it to sugar. Because the e- increases in PE as they move from H2O to sugar, this process requires energy. Th energy boost is provided by light.
Stomata
Small openings on the underside of a leaf through which oxygen and carbon dioxide can move and that permit evaporation of water. They are open during the day for photosynthesis and closed at night.
___ are guard cells that are open during the day and closed at night.
Stomata
Describe how the two stages of photosynthesis are dependent on each other.
The calvin cycle depends on the NADPH and ATP that light reaction generates. Light reactions depend on NADP+ and ADP (+) P that the calvin cycle generates.
Cyclic electron flow
The e- cycle back from ferredoxin (fd) to the cytochrome complex and from there continue to a P700 chlorophyll in the PSI reaction center. There is NO production of NADPH and no release of O2. Cyclic flow does generate ATP. Consumes more ATP that NADPH. Cyclic flow makes up the difference since it produces ATP by not NADPH.
stroma
The fluid of the chloroplast surrounding the granum; involved in the synthesis of organic molecules from carbon dioxide and water.
Why do leaves change color in the fall?
The plants stop making chlorophyll in the fall, which allows pigments other than green to be revealed.
T/F: The top of leaves are waterproof and the bottom of them are not waterproof.
True
True/False: Light has wave characteristics and particle characteristics.
True - light can bend like a wave and can become excited like a particle
Ruben and Kamen
Used an isotope of oxygen to prove Van Niel correct; that oxygen came from the breakdown of water, not CO2
The sun radiates the full spectrum of electromagnetic energy, but the atmosphere only allows visible light to ass through while filtering out a substantial fraction of other radiation. ___ drives photosynthesis.
Visible light
___ is split during photosynthesis, providing the electrons needed to produce carbohydrates. It provides the source of electrons in the formation of carbohydrate from CO2 during photosynthesis.
Water
Chlorophyll ___ is the only chlorophyll molecule that has the atomic configuration to pass the e- on to a receiver.
a
What structure is found within the thylakoid membrane?
a light harvesting antennae (contains chlorophyll)
Photosynthesis
a process that uses light energy and simple molecules to make carbohydrates
granum
a stack of thylakoids in a chloroplast; functions in the light reaction of photosynthesis
There are different types of chlorophyll that absorbs different colors, which makes photosynthesis more efficient. What are the types?
chlorophyll a (blue-green), chlorophyll b (yellow-gren), carotenoids (yellow-orange)
What are the only parts of the plant that are green?
chloroplasts
During the general process of photosynthesis, the energy from light is used to accomplish the oxidation of water. Water is split to form oxygen gas in the light ____ reactions.
dependent
Light-___ reactions take in water and produce oxygen to make ATP and NADPH. Water is split is this reaction.
dependent
Chemiosmosis
energy coupling mechanism that uses energy stored in the for of H+ gradient across a membrane to drive work, such as synthesis of ATP. Most ATP synthesis in cells occur by chemiosmosis.
A chlorophyll a electron can move to an excited state directly by light or indirectly by the transfer of energy from another ____.
excited e-
Once absorption of a photon raises an e- from the ground sate to an excited state, the e- can not remain there long and is unstable. When the e- falls back down, the energy is released as heat. As excited e- fall back down to the ground state, photons are given off. This afterglow is called ___.
fluorescence
What is in a chloroplast?
granum made up of thylakoids, stroma, and it has a two membrane structure
Why is chlorophyll green?
green has the lowest rate of photosynthesis (less absorption of photons), and when you see a color it is because it reflects that color, not absorbing it. In other words, low absorption of green means a low rate of photosynthesis.
chlorophyll
green pigment in plants that absorbs light energy used to carry out photosynthesis; it is the light energy absorbed by chlorophyll that drives the synthesis of organic molecules in the chloroplast
Through heat loss and fluorescence, the electron returns to _____ state. The energy released is used to pump H to reduce coenzymes.
ground
carotenoids
have an orange pigment, which explains the fall pigments; they absorb wavelength color of red and orange that chlorophyll can not
Light-___ reaction involves the uptake of CO2 to make carbohydrates. Carbon fixation happens in this reactions.
independent
The P680 and P700 are identical chlorophyll a molecules but their association with different proteins in the thylakoid membranes affects the e- distribution in chlorophyll molecules and accounts for different _____.
light absorbing properties
The ____ are groups of pigments that help capture energy from light in a photosystem.
light harvesting antennae
What are the two stages of photosynthesis?
light reactions ("photo") and the calvin cycle ("synthesis")
Red light has ___ energy than blue light.
lower
The ___ of the leaf is a tissue composed of cells separated by numerous air spaces.
mesophyll
Where is the major site of photosynthesis in the leaf?
mesophyll
Mesophyll
middle layer of cells; carries out photosynthesis
Autotroph
organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer
The only ___ absorbed are those whose energy is exactly equal to the energy difference between the ground state and an excited state, and this energy difference varies. So, a particular compound absorbs only ___ corresponding to specific wavelengths, which is why each pigment has a unique absorption spectrum.
photon; photon
Light is composed of particle energy called ___.
photons
Substances that absorb visible light are known as ___, and different ones absorb different wavelengths.
pigments
Chlorophyll contains a _____ ring that has a HC tail attached. Magnesium (Mg) is found in the center of it.
porphyrin
The ___ ring is where the light is picked up.
porphyrin
When a molecule absorbs a photon of light, one of the molecules e- is elevated to an orbital where it has more ____.
potential energy (normal orbital is ground state, orbital of higher energy is excited state)
Non-cyclic electron flow
produces ATP and NADPH is equal amounts; predominant route; the light reactions use solar power to generate ATP and NADPH, which provide chemical energy and reducing power to the sugar making reaction of the calvin cycle (P680)
Photosynthetic ___ lack chloroplasts, but they do have photosynthetic membranes arising from in-folded regions of the plasma membrane that function in a manner similar to the thylakoid membranes of chloroplasts.
prokaryotes
Thylakoids are membrane enclosed sacks embedded with ____ and light harvesting antennae containing ___.
proteins; chlorophyll
The energy content for visible light is greatest for the visible light of __.
purple
Chlorophyll glows ___ when it's hit with UV light because energy is released from an electron that falls to is ground state.
red - because as it is hit with UV it's electron was excited to a higher energy level by UV light and as it falls back down to ground state, it emits light energy
Different colors of light have different wavelengths, which have different amounts of energy. Which colors have the highest rate of photosynthesis? lowest?
red and blue; green
In the thylakoid, the excited e- is taken from chlorophyll causing a _______.
redox reaction
Leaves appear green to us because green light is largely ___. Chlorophyll, a major pigment in leaves, does not absorb green wave lengths of light effectively.
reflected
The ability for a pigment to absorb various wavelengths of light can be measured with a ___.
spectrophotometer
In photosynthesis, energy from light is used to ____.
split water
CO2 is taken in and H20 vapor and O2 are released through the ___ and functions in the exchange of gases between a plant and its environment.
stomata
What part of the leaf can open and close, often found on the underside of the leaf, and are small pores composed of two guard cells?
stomata
What happens when a photon hits an electron? This is called photoelectric effect or photo-excitation.
the electron moves from a stable position to an unstable one
photoexcitiation
the energizing of e- from their ground state to higher orbitals in the absorption of light as energy; an electron gains energy when hit by a photon
Hw id the use of oxygen isotope help elucidate the chemistry of photosynthesis?
the heavy element was tracked to prove oxygen came from H2O and not CO2 (Van Neil)
What happens when water containing an oxygen isotope is supplied to a plant?
the oxygen isotope is released into the air
Plants get wet for photosynthesis through ___.
veins
The span of the electromagnetic spectrum most important to life is the narrow band from about 380 nm to 75 nm in wavelength. This is known as ___.
visible light
Distances between the crest of each electromagnetic wave is called ___. The entire range of radiation is called the electromagnetic spectrum. The shorter the wavelength, the greater the energy.
wavelength
Light is a form of energy knows as electromagnetic energy or electromagnetic radiation. Electromagnetic energy travels is ___. Electromagnetic waves are disturbances of electric and magnetic fields rather than disturbances of a material medium such as water.
waves
What part of the leaf keeps the leaf from losing all its water through evaporation?
waxy cuticle
