Renton Tech College, Wa
Terms in this set (49)
An organelle found in plant and algae cells where photosynthesis occurs
Where does all the energy on earth ultimately come from?
A green pigment found in the chloroplasts of plants, algae, and some bacteria
The ground tissue of a leaf, sandwiched between the upper and lower epidermis and specialized for photosynthesis.
flattened sacs inside a chloroplast, bounded by pigmented membranes on which the light reactions of photosynthesis take place, and arranged in stacks or grana.
Stacks of thylakoids. The granum contains the light harvesting system composed of chlorophyll and phospholipids.
Interior space of thylakoid, This energy is used to pump H+ into the thylakoid space/
Horizontal distance between the crests or between the troughs of two adjacent waves
..., Colored chemical compounds that absorb light
An accessory pigment, either yellow or orange, in the chloroplasts of plants. By absorbing wavelengths of light that chlorophyll cannot, carotenoids broaden the spectrum of colors that can drive photosynthesis.
A light-capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes, consisting of a reaction-center complex surrounded by numerous light-harvesting complexes. There are two types of photosystems, I and II; they absorb light best at different wavelengths.
Ribulose carboxylase, the enzyme that catalyzes the first step of the Calvin cycle (the addition of CO2 to RuBP, or ribulose bisphosphate).
Bundle sheath cells
, A type of photosynthetic cell arranged into tightly packed sheaths around the veins of a leaf of c4 plant.
A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allow gases (CO2 and O2) and water to diffuse in and out of the leaves.
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate.
A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into four-carbon compounds, the end product of which supplies CO2 for the Calvin cycle.
Store the organic acids made at night in vacuoles and use them for photosynthesis during the day when stomata are closed
A 3 carbon sugar; for each CO2 are formed in the Calvin cycle; 1 leaves to be used in the cell, 5 are use for regeneration of RuBP
First stage of photosynthesis. Named Because it requires light to happen. Begins with the absorption of light in the Chloroplasts.
A biochemical pathway of photosynthesis in which carbon dioxide is converted into glucose using ATP and NADPH.
NADP+ and NADPH
The electrons derived from this oxidation reaction in the light reactions are used to reduce ____ to _____.
A metabolic pathway that consumes oxygen, releases carbon dioxide, generates no ATP, and decreases photosynthetic output; generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide.
What kinds of organisms photosynthesize? What kinds of organisms do cellular respiration? (choices: animals, plants, fungi, protists, bacteria, archaea)
Plants and some bacteria and algae
Why don't we keep lots of ATP stored in our cells all the time?
ATP is great for TRANSFERRING ENERGY, but not good for storing large amounts of energy for the long term. Cells only keep enough ATP
around to last a few seconds andrecharge it by burning glucose.
What parts of plants tend to have lots of chloroplasts? What color are they?
chloroplasts are mostly in the mesophyll of leaves and are green
Know the overall chemical reaction for photosynthesis and how it is related to the reaction for cellular respiration.
6 CO2 + 12 H2O + energy ---> C6H12O6 + 6 O2 + 6 H2O
Which reactant in photosynthesis becomes oxidized? Which becomes reduced? Which one is the oxidizing agent? Which is the reducing agent?
Be able to summarize in a sentence what happens in each of the 2 stages of photosynthesis.
IMPOSSIBLE! carbon dioxide is reduced to glucose and water is oxidized to oxygen....
What molecule acts as the major electron carrier in photosynthesis?
NADH+ and FADH=
What colors of visible light have the shortest and longest wavelengths?
Violet having the shortest wave length our eyes can see, and red having the longest. ROY G BIV
Do photons of blue light or photons of red light have more energy?
Shorter the wave the have more energy= violet, vs. red, less energy
When light hits something, what 3 things can happen to it?
light can absorbed, transmitted, or reflected
Do we see the color of light that is absorbed, transmitted, and/or reflected?
Reflected and Transmitted
Plants are usually green. Does that mean they are absorbing green light?
NOPE, it absorbs all colors but green.
What experiment did Engelmann use to determine what wavelengths of light were being absorbed by plants?
In 1883, Theodor W. Engelmann illuminated a filamentous alga with light that had been passed through a prism, exposing different segments of the alga to different wavelengths.
He used aerobic bacteria, which concentrate near an oxygen source, to determine which segments of the alga were releasing the most O2 and thus photosynthesizing most. Bacteria congregated in greatest numbers around the parts of the alga illuminated with violet-blue or red light.
The conclusion of this experiment was that light in the violet-blue and red portions of the spectrum is most effective in driving photosynthesis.
What happens to the electrons in chlorophyll when light hits them?
Light hits Photosystem II (P 680) causing electrons to be boosted to a higher energy level and pass into an electron transport chain.
In isolated chlorophyll solutions, what happens when excited electrons move back down to lower electron shells?
Absorption of a photon causes a transition of the chlorophyll molecule from its ground state to its excited state.As excited electrons fall back to the ground state, photons are given off. This afterglow is called fluorescence. If a solution of chlorophyll isolated from chloroplasts; it will fluoresce in the red-orange part of the spectrum and also give off heat.
What are the two major parts of a photosystem?
Photosystem II (PS II) functions first and is best at
absorbing a wavelength of 680 nm
The reaction-center chlorophyll a of PS II is called
Photosystem I (PS I) functions later and is best at
absorbing a wavelength of 700 nm
The reaction-center chlorophyll a of PS I is called
Be able to describe what happens in the light reactions. Where does energy come from? How does that energy get transferred? What happens to the electrons? What molecules are produced?
Solar energy is converted to chemical energy. Light is absorbed by chlorophyll and by doing so there is a transfer of electrons and H+ ions to NADP+. Thus NADP+ is reduced to NADPH. ATP is also produced and when the energy from light is used to help catalyze the reaction between ADP and Pi, it is called photophosphorylation.
What are electron transport chains useful for? Why don't we just give electrons to the one molecule at the end and be done with it?
If the light reactions don't make any sugar, why do plants need them for photosynthesis?
When inorganic carbon (like from CO2) is being added to an organic molecule (such as sugar), this is called carbon fixation.
What type of sugar is produced in the Calvin cycle? How many times does the cycle need to turn to get 1 sugar molecule?
Sugar/Glucose (C6H12O6). Twice.
What molecules does the Calvin cycle use as reactants?
carbon dioxide (CO2)
Know the 3 phases of the calvin cycle and the basics of what happens in each.
3. Carbon fixation: 3 RuBP + 3 CO2 => 6 3-Phosphoglycerate. [atmospheric CO2 becomes covalently bonded to RuBP with enzyme Carboxylase, Oxygenase]
2. Reduction: Reduction: each molecule of 3-phosphoglycerate gets an additional phosphate group from ATP
3. Regeneration of CO2 acceptor: 5 molecules of G3P into 3 molecules of RuBP
Why would a plant want to close its stomata?
Stomata are the openings through which plants respire. The stomata are flanked by two guard cells, which control the size of stomatal openings. Guard cells thus regulate the flow of gas and water between the leaf and its environment. Plants typically close their stomata at night to avoid too much water loss.
C3 plants are your regular everyday plants, they open their stomata during the day to breathe in CO2 and release O2. they go through the light and dark reactions normally because they are not exposed to extremely hot conditions. C4 plants and CAM plants have devised ways to overcome the rough environment.
C4 plants have 2 separate cells, mesophyll cells and bundle sheath cells. C4 plants use this method to combat photorespiration, which is when the plants breakdown glucose to form CO2 instead building glucose from CO2 and releasing O2. the CO2 enters the mesophyll cell, and PEP (phosphoenolpyruvate) carboxylase binds the CO2 to PEP to produce a 4 carbon compound. PEP carboxylase has no affinity for O2, unlike rubisco, which is why it will bind with the CO2 instead of the O2 in the plant. so the 4 carbon compound (could be oxaloacetate, malate) is then transferred through plasmodesmata to the bundle sheath cells, where it is broken down to CO2 and pyruvate. and the CO2 enters the calvin cycle to produce glucose. the pyruvate is then sent back to the mesophyll cells and with the use of ATP is converted to back to PEP so that it can combine with more CO2.
CAM plants also developed because of photorespiration. the difference between CAM and C4 is that CAM plants have only one cell, and they they open their stomata at night and close them during the day. the CO2 they take in at night is incorporated into 4 carbon compounds (organic acids) and is sent off to the calvin cycle during the day to make glucose. CAM plants are usually found in dry desert areas.
How many CO2 is required to make one glucose?
Glucose has six carbons. CO2 has one carbon. It takes six CO2 molecules to make one glucose molecule.
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