Flashcards in Unit 3 Test Deck (86):
Electronegativity increases going from _______ to _______ on the periodic table
down to up
left to right
In photosynthesis, what form is energy from the sun stored in?
In photosynthesis, what form is potential energy stored in?
What is the first step in cellular respiration?
What is glycolysis?
The process of breaking glucose into two pyruvate.
Why is glucose used in cellular respiration?
Because it's an effective molecule for storing energy and is relatively small.
How does glucose enter the cell?
Why is glucose phosphorylated before broken down into pyruvate?
To keep it in the cell and raise its potential energy.
What are two two types of ATP phosphorylation?
Substrate level phosphorylation and oxidative phosphorylation.
What is substrate level phosphorylation?
When a phosphate is removed from a sugar to create ATP from ADP.
What is oxidative phosphorylation?
When a proton gradient is used to phosphorylated ATP from ADP.
What is the purpose of NAD+ in glycolysis?
To oxidize the sugar
Where does glycolysis take place?
The cytosol of a cell
What are the byproducts of glycolysis?
2 ATP and 2 NADH
What is the pyruvate dehydrogenase reaction?
The reaction preceding the Krebs Cycle where pyruvate is oxidized into Acetylene CoA.
Where does the pyruvate dehydrogenase reaction take place?
In the mitochondria (as the pyruvate moves into it from the cytosol).
What are the byproducts of the Acetyl CoA Step?
2 CO2 and 2 NADH.
What is the Krebs Cycle?
A cycle where Acetyl CoA undergoes many reactions to produce CO2, NADH, ATP, and FADH2.
What is the starting molecule of the Krebs Cycle?
How many turns are needed in the Krebs Cycle for each glucose molecule and why?
2, since each glucose molecule is broken down into two different pyruvate, and each pyruvate must go through the cycle separately.
Where does the Krebs Cycle take place?
In the matrix of the mitochondria.
Why does the Krebs Cycle have so many steps?
So that excessive amounts of energy will not be lost as heat.
What are the products of the Krebs Cycle?
4 CO2, 4 NADH, 2 ATP, and 2 FADH2.
What is the final step of cellular respiration?
The electron transport chain.
What is the electron transport chain?
A sequence of mitochondrial membrane proteins that shuttle electrons in a series of redox reactions to make a concentration gradient.
What are the components of the mitochondrial electron transport chain?
Cytochrome B, ATP synthase, Cytochrome C, Quinine, and FMN.
Which electron carriers are responsible for the redox reactions in the cellular respiration electron transport chain?
NADH and FADH2.
In cellular respiration, protons are pumped from the ________ to the _________.
matrix to the intermembrane space
In cellular respiration, protons diffuse from the __________ to the __________ to power the ATP synthase.
intermembrane space to the matrix.
How much ATP is produced for each NADH and FADH2 in the mitochondrial electron transport chain?
Each NADH produces about 3 ATP, and each FADH2 produces about 2 ATP.
Around how much ATP is produced in the mitochondrial electron transport chain?
32 to 34 ATP.
In total, what products are formed in cellular respiration?
6 CO2, 10 NADH, 2 FADH2, and 36 to 38 ATP.
What is anaerobic respiration?
The use of an inorganic molecule other than oxygen to accept electrons at the end of the mitochondrial electron transport chain (a type of cellular respiration).
What is fermentation?
The partial breakdown of sugar with no use of oxygen or an electron transport chain.
What is alcohol fermentation?
The three step process where pyruvate is converted first into acetaldehyde, then into ethanol.
Is cellular respiration endergonic or exergonic?
Is cellular respiration anabolic or catabolic?
What color light drives most photosynthesis?
Purplish-blue and red light
What are photoreceptors?
Different pigments found in plants.
What are three of the most common photoreceptors?
Chlorophyll A, chlorophyll B, and carotenoids.
What is chlorophyll A?
A photoreceptor that participates directly in light reactions by donating electrons.
What is chlorophyll B?
An accessory pigment that doesn't directly donate electrons but still absorbed light.
What are carotenoids?
Accessory pigments that absorb and dissipate light that might harm the plant, and prevent oxidative molecules from forming.
What are photosystems?
Light capturing units made from a reaction center complex and a light harvesting complex.
What is the reaction center complex?
Complex proteins and associated chlorophyll A.
What is the light harvesting complex?
Complex proteins and associated chlorophyll A, chlorophyll B, and carotenoids.
What are the two possible electron routes?
Linear electron flow and cyclic electron flow.
What is the path of linear electron flow?
An electron route using both photosystems 1 and 2 where ATP, O2, and NADPH are produced.
What is cyclic electron flow?
An electron route consisting of only photosystem 1, where the product is only ATP.
What is lactic acid fermentation?
The two step process where pyruvate is reduced by NADH.
In photosystem 2, how is P680 reduced into its original state?
Water is split into 2 electrons, 2 H+, and 1 O. The electrons reduce the P680, and the O meets up with a second O to make O2.
What is the electron transport chain in photosystem 2 made from?
Plastoquinone (Pq), Cytochrome complex, and Plastocyanin (Pc).
In the photosystem 2 electron transport chain, protons are pumped from the _________ to the _________.
Strom a to the thylakoids lumen.
In the photosystem 2 electron transport chain, protons diffuse from the _________ to the _________ to power ATP synthase.
Thylakoid lumen to the stroma.
What is the special chlorophyll that transfers electrons in a redox reaction in photosystem 1?
How is P700+ reduced back into P700?
By electrons from the photosystem 2 electron transport chain.
What are the proteins in the photosystem 1 electron transport chain?
Ferredoxin (Fd) and NADP+ reductase.
What is a big difference between the photosystem 1 electron transport chain and the photosystem 2 electron transport chain?
Chemiosmosis (the pumping of protons to power ATP synthase) does not occur in the photosystem 1 electron transport chain.
Why will cyclic electron flow occur?
If there isn't enough NADP+ in the photosystem 1 electron transport chain to receive electrons, the electrons will back up and enter cyclic electron flow.
What is produced in cyclic electron flow?
ATP, but no O2 or NADPH.
What happens in cyclic electron flow?
Electrons move from the Ferredoxin (Fd) of the photosystem 1 electron transport chain to the cytochrome complex of the photosystem 2 electron transport train.
What is the Calvin Cycle?
A light independent reaction that is part of photosynthesis, where ATP produced from the electron transport chains is used to create glucose.
What are the starting molecules of the Calvin cycle?
CO2 and RuBP.
What is the ending molecule of the Calvin Cycle?
G3P, a 3-Carbon sugar.
How many turns of the Calvin Cycle are needed to create one G3P?
3 turns, since 3 CO2 are needed and they enter the cycle one at a time.
How much ATP is needed to make one G3P?
What is the difference between alcohol fermentation and lactic acid fermentation?
Alcohol fermentation releases CO2 while lactic acid fermentation does not.
What are obligate anaerobes?
Organisms that can only live by anaerobic respiration (no oxygen).
What are the steps leading to the light reaction in photosystem 2?
1. Light is absorbed by pigments
2. Electrons jump to an exited state, fall back down, and excite an adjacent pigment
3. Special chlorophyll A (P680) transfers electrons in a redox reaction.
What is the end product of photorespiration?
Why is photorespiration considered to be wasteful?
Because it uses ATP while producing very little.
What are facultative anaerobes?
Organisms that use aerobic respiration when oxygen is present, but can still survive off of anaerobic respiration.
What are the second steps of cellular respiration?
The Acetyl CoA step and the Krebs Cycle.
Does photorespiration increase or decrease when temperature increases? Why?
Increase, since O2 will be more dissolved in the atmosphere than CO2 , the stroma will partially close which will reduce CO2 intake, and a higher light intensity increases the rate of photosynthesis which decreases CO2 availability.
What is photorespiration?
A light-dependent reaction that detours from the Calvin Cycle in the absence of CO2, active in C3 plants that produces sugar.
What are C4 plants?
Plants with a low rate of photorespiration and water loss, and a high rate of photosynthesis. They are typically found in tropical areas.
Where are CAM plants found?
Dry, arid, and hot environments.
How do CAM plants minimize their water loss?
By closing their stomata (this also prevents CO2 from entering during the day).
How do C3, C4, and CAM plants differ in carbon fixation?
In C3, CO2 is fixated in the Calvin Cycle, while in C4 and CAM, it's fixated before.
In C4, CO2 is fixated in the mesophyll, and the Calvin Cycle takes place in the bundle sheaths.
In CAM, CO2 is fixated at night, and the Calvin Cycle is during the day.
What are the steps of the C4 Calvin cycle?
1. PEP carboxylate fixes CO2 to a 3-Carbon compound (PEP), which becomes oxaloacetate.
2. Oxaloacetate becomes malate, another 4-Carbon compound.
3. Malate moves to the bundle sheath cells and releases CO2, becoming 3-Carbon pyruvate.
4. Pyruvate returns to the mesophyll and is converted back to PEP.
Which 3 structures does photorespiration take place in?
The chloroplasts, the Peroxisomes, and the mitochondria.
How do C4 plants differ from C3 plants?
C4 plants start with a 4-Carbon molecule called oxaloacetate, while C3 plants start with a 3-Carbon molecule (G3P). Also, in C4 plants, the Calvin cycle takes place in bundle sheaths, while in C3 plants, it takes place in the mesophyll.
What are the purposes of the different structures used in photorespiration?
Chloroplast: O2 and RuBP combine to form glycolate
Peroxisomes: chemical reactions convert glycolate to glycine
Mitochondria: glycine is converted to serine with a CO2 release
Peroxisomes: serine converted to 3-Carbon glycerate
Chloroplast: glycerate is converted to PGA to re-enter the Calvin Cycle
What enzyme is used in the Calvin Cycle and in photorespiration?
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