Bio Exam 3
Compare ATP formation by the photosynthetic electron transport chain to the operation of a hydroelectric dam, where a turbine powered by downhill water flow produces electricity. In this analogy, water stands for ________, the turbine stands for ________, and electricity production stands for _________.
the protons (H+), the ATP synthase, the ATP produced
Carbon dioxide bonds with ________ held electrons is converted to sugar bonds with ______ held electrons in the Calvin cycle.
tightly; loosely
What is the primary function of the Calvin cycle?
to synthesize a simple sugar (G3P) from carbon dioxide
Which of these is a source of lactose?
milk (Lactose is the sugar found in milk.)
Where in a leaf are ATP synthases located? A) Only in the thylakoid membrane and the inner mitochondrial membrane B) Only in the cell membrane C) Only in the inner mitochondrial membrane D) In the thylakoid membrane, the cell membrane, and the inner mitochondrial membrane E) Only in the thylakoid membrane
Only in the thylakoid membrane and the inner mitochondrial membrane
Burning of natural gas (methane, CH4) releases energy because A) methane contains tightly held electrons. B) carbon dioxide and water contain loosely held electrons. C) oxygen reacts with bonds with loosely held electrons. D) bonds with electrons held tightly by oxygen are converted to bonds with electrons evenly shared by the partner atoms. E) C=O and O-H bonds are converted to C-H bonds.
oxygen reacts with bonds with loosely held electrons.
Predict features of C3 and C4 plants resulting from the fact that (i) C4 plants require more ATP to fix CO2 than C3 plants and (ii) C4 plants are able to fix CO2 at much lower internal CO2 concentrations than C3 plants. A) C4 plants do not need to open their leaf pores as widely as C3 plants to do photosynthesis. B) C4 plants lose less water than C3 plants through their leaf pores. C) C4 plants need more energy from sunlight than C3 plants D) A and B E) A, B, and C
A, B, and C (explanation: C4 photosynthesis is more efficient than the Calvin cycle at incorporating (fixing) CO2 into a new molecule (a 4-carbon molecule in C4 plants or a 3-carbon molecule in C3 plants). Therefore, C4 plants are able to carry out as much photosynthesis as C3 plants with their leaf pores less widely open. As a consequence, C4 plants lose less water than C3 plants. However, C4 photosynthesis requires additional ATP. So, E (comprised of answers A, B, and C) is the correct answer.)
Predict the effect of the uncoupling protein: A) No ATP is produced by the ATP synthase. B) Glycolysis and the citric acid cycle continue to run. C) Electron transport continues to run and the energy of high-energy electrons is released as heat. D) A and C E) A, B, and C
A, B, and C (explanation: The uncoupling protein allows protons to flow from the intermembrane space back into the matrix without any of that energy being captured to form ATP. The rest of the cellular respiratory reactions will continue to occur, including glycolysis and the citric acid cycle as well as mitochondrial electron transport. In other words, E is the correct answer!)
Glycogen is _____.
a polysaccharide found in animals (Animals store energy in the form of glycogen.)
The immediate next energy-rich state formed with energy provided by electrons flowing through the mitochondrial electron transport chain is
a proton gradient (Explanation: Electrons flowing through the mitochondrial electron transport chain move protons into the mitochondrion's intermembrane space, where protons pile up like water behind a dam (just as is the case in the inner thylakoid space in chloroplasts that are absorbing light). Therefore, the immediate next energy-rich state formed with energy provided by electrons flowing through the chain is a proton gradient. ATP formation is the next step after that. Mitochondria do not form glucose. Water does not represent an energy-rich state; the electrons that combine with oxygen to form water have already lost their energy. The energy for NADH formation in mitochondria is provided by transfer of high-energy electrons to NAD+ from remainders of glucose molecules in the citric acid cycle. NADH is the source of the energized electrons that enter the mitochondrial electron transport chain.)
Fast-twitch muscle fibers have the advantage of ________ and the disadvantage of _________. A) extracting a lot of energy from glucose; not being able to perform over extended periods B) using fat as a long-lasting energy source; not being able to use oxygen C) acting quickly; not extracting a lot of energy from glucose D) acting over extended periods; not being able to use fat as an energy source E) making a lot of ATP; not being able to operate without oxygen
acting quickly; not extracting a lot of energy from glucose (explanation: Fast-twitch muscle fibers, that generate ATP through glycolysis and lactic acid fermentation, can act quickly to extract energy from glucose (rather than from fat) but produce only a tiny bit of ATP. These muscle fibers run out of glucose very quickly. Slow-twitch muscle fibers, on the other hand, rely on fat as their energy source and feed electrons from the C-H bonds of this fat into their mitochondria, where they produce lots and lots of ATP in the mitochondrial electron transport chain with the help of oxygen as the final electron acceptor. While these fibers don't act quite as quickly as fast-twitch muscle fibers, they can continue to operate over longer periods of time without experiencing fatigue.)
Which molecules can be utilized directly or after some breakdown in cellular respiration to generate ATP?
amino acids, protein, glycerol, fatty acids, glucose, sucrose, starch, and glycogen
Inputs and outputs What goes into the Citric Acid Cycle? ______________ ______________ ______________
Acetyl-CoA NAD+ A little ADP + P
Find the statement that is FALSE. First exclude the four statements that are true. Starch and cellulose A) are both synthesized by and found in plants. B) both contain a lot of energy. C) are both made of glucose monomers. D) are both structural components of plant cell walls. E) are both polysaccharides.
are both structural components of plant cell walls. (Explanation: Both starch and cellulose are made of glucose monomers that contain energy. However, cellulose cannot serve as a source of usable calories for humans and most other animals because they are unable to digest cellulose. While both are polymers of glucose (i.e., polysaccharides) synthesized by plants, only cellulose is found in cell walls.)
Hint 1. The relationship of light to the Calvin cycle In most plants, the Calvin cycle occurs only in the light because it requires an input of chemical energy and reducing power from the light reactions. However, if the compounds that shuttle this chemical energy and reducing power from the light reactions are artificially provided to a chloroplast, the Calvin cycle can proceed in the dark. Consider what this means about whether light plays a direct role in the Calvin cycle. Hint 2. What is the product of the Calvin cycle that contains "fixed" carbon?The Calvin cycle uses energy from the light reactions to "fix" inorganic carbon into sugar. What is the product of the Calvin cycle that contains this fixed carboN? A) RuBP B) G3P C) CO2 D) glucose
glucose
Inputs and Outputs what goes into glycolysis? ______________ ______________ ______________
glucose NAD+ a little ADP + P
The uncoupling protein converts energy provided by ______ to _______.
glucose; heat
Part A - Inputs and outputs of the light reactions From the following choices, identify those that are the inputs and outputs of the light reactions. (Recall that inputs to chemical reactions are modified over the course of the reaction as they are converted into products. In other words, if something is required for a reaction to occur, and it does not remain in its original form when the reaction is complete, it is an input.) Drag each item to the appropriate bin. If the item is not an input to or an output from the light reactions, drag it to the "not input or output" bin.
(In the light reactions, the energy of sunlight is used to oxidize water (the electron donor) to O2 and pass these electrons to NADP+, producing NADPH. Some light energy is used to convert ADP to ATP. The NADPH and ATP produced are subsequently used to power the sugar-producing Calvin cycle.)
To make sugars, photosynthesis obtains carbon atoms from _______ and H (electrons and H+) from_____. A) carbon dioxide; water B) starch; water C) carbon dioxide; NADH D) glucose; NADH E) cellulose; water
(carbon dioxide; water explanation: The carbon atoms that are incorporated into the sugar products of photosynthesis come from the gas carbon dioxide. Some could come from carbon dioxide released through cellular respiration in a plant's own cells, but the majority of carbon dioxide molecules come from the atmosphere. The electrons that become energized and enter the photosynthetic electron transport chain, as well as the H+ that accumulate in the thylakoid membrane spaces before moving through the ATP synthase, both come from water molecules that are split into electrons, protons, and oxygen atoms. Starch, glucose, and cellulose are carbohydrates that are products of photosynthesis. NADH shuttles electrons plus H+ obtained from C-H bonds of food molecules into mitochondria. It is NADPH that provides electrons plus H+ for making sugars in the Calvin cycle of photosynthesis.)
Advantages of photosynthetic algae & bacteria
-Minimal food versus food conflict -Can be grown in areas not suitable for crop growth -Some can be grown in brackish water or saltwater -Some release their energy-rich products, making energy-intensive harvesting unnecessary
check all that are services of photosynthesis or plants for human society: -help with climate control -production of oxygen -contribution to the ozone layer -production of fossil fuel -production of fiber -food production -production of building materials -balancing atmospheric CO2 levels -production of biofuels
-help with climate control -production of oxygen -contribution to the ozone layer -production of fossil fuel -production of fiber -food production -production of building materials -balancing atmospheric CO2 levels -production of biofuels (explanation: These are the main reasons why plants are said to be the foundation of the biosphere and human civilization.)
Ethanol from different plant sourcesFrom a joint study conducted by the Department of Energy and the Department of Agriculture: Comparison of "estimated reduction in greenhouse gas emissions if petroleum fuel were replaced by ethanol" 1) Ethanol from corn starch - ___ % 2) Ethanol from sugarcane sucrose - ____ % 3) Ethanol from cellulose from some grasses & trees (cellulosic ethanol) - ______ %
1) Ethanol from corn starch - -22% 2) Ethanol from sugarcane sucrose - -56% 3) Ethanol from cellulose from some grasses & trees (cellulosic ethanol) - -91%
Describe the sequence of events in mitochondrial electron transport from input of high-energy electrons by NADH all the way to ATP formation.
1. High-energy electrons from food are fed into the electron transport chain via NADH. 2. Electrons flowing through the electron transport chain give up energy to build a proton gradient by moving H+ from low concentration in the matrix to ever-increasing concentration in the space between the inner and outer membranes (the intermembrane space). 3. Subsequent utilization of this proton gradient energizes ATP formation: H+ flow back from high concentration in the intermembrane space to low concentration in the matrix through the ATP synthase turbine that forces a third phosphate group onto ADP.
The mitochondrial electron transport chain makes ATP just like the photosynthetic electron transport chain. Fill in the blanks, using your document for the exam. 1. High-energy electrons from food are fed into the electron transport chain via NADH. 2. Electrons in the electron transport chain give up energy to build a _____ gradient by moving _____ from _____ concentration in the matrix to _____ concentration in the intermembrane space. 3. Utilization of the proton gradient energizes _____ formation by the ATP synthase turbine: _____ flows from _____ concentration in the intermembrane space to _____ concentration in the matrix through the ATP synthase turbine that forces a third phosphate group onto ADP.
1. High-energy electrons from food are fed into the electron transport chain via NADH. 2. Electrons in the electron transport chain give up energy to build a proton gradient by pumping H+ from low H+ concentration in the matrix to high H+ concentration in the intermembrane space. 3. Utilization of the proton gradient energizes ATP formation by the ATP synthase turbine: H+ flows from high H+ concentration in the intermembrane space to low H+ concentration in the matrix through the ATP synthase turbine that forces a third phosphate group onto ADP.
Fill in the blanks: 1. Sunlight energizes electrons of chlorophyll that leave chlorophyll and are continuously replaced by electrons from _____ - Water is split into electrons, H+, and oxygen 2. The energized electrons flow through the photosynthetic electron transport chain - Pump _____ from the stroma into the thylakoid space - Next, H+ flowing through the ATP synthase turn the turbine - Energizes ATP formation by the ________ 3. Light energizes electrons again for loading onto NADP+ - NADPH and ATP go to the Calvin Cycle to make sugar.
1. Sunlight energizes electrons of chlorophyll that leave chlorophyll and are continuously replaced by electrons from water - Water is split into electrons, H+, and oxygen 2. The energized electrons flow through the photosynthetic electron transport chain - Pump H+ from the stroma into the thylakoid space - Next, H+ flowing through the ATP synthase turn the turbine - Energizes ATP formation by the ATP synthase. 3. Light energizes electrons again for loading onto NADP+ - NADPH and ATP go to the Calvin Cycle to make sugar.
Which of these equations best summarizes photosynthesis? A) C6H12O6 + 6 O2 → 6 CO2 + 12 H2O B) C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy C) 6 CO2 + 6 O2 → C6H12O6 + 6 H2O D) H2O → 2 H+ + 1/2 O2 + 2e- E) 6 CO2 + 6 H2O → C6H12O6 + 6 O2
6 CO2 + 6 H2O → C6H12O6 + 6 O2
Hint 3. Which product or products of the Calvin cycle is/are returned as input(s) to the light reactions?Which of the following outputs from the Calvin cycle are also inputs to the light reactions?Select all that apply. A) G3P B) ADP C) NADP D) NADPH E) ATP
ADP NADP
P = phosphate (same as Pi = inorganic phosphate) Predict where ADP and P go after ATP fuels the Na+/K+ pump in the outer cell membrane of an animal cell. A) ADP and P accumulate in the cytosol and don't form ATP again. B) ADP and P are regenerated to ATP by the Na+/K+ pump running in reverse. C) ADP and P are regenerated to ATP in the chloroplasts. D) ADP and P are regenerated to ATP in the mitochondria. E) C and D
ADP and P are regenerated to ATP in the mitochondria (explanation: If ADP and P were to accumulate in the cytosol, the supply of ADP and P to form new ATP in the mitochondrion would rapidly run out. The sodium-potassium pump does not run in reverse - it utilizes ATP forming ADP and P, but not the other way around. Since the question concerns an animal cell, there is no generation of ATP in chloroplasts. This leaves only answer D - that ADP and P return to mitochondria to be regenerated to ATP.)
Which statement correctly describes an event that is part of the light reactions of photosynthesis. A) Electrons are extracted from sugar. B) ADP is phosphorylated to form ATP. C) Carbon dioxide is incorporated into a sugar. D) NADP+ is produced. E) water is produced
ADP is phosphorylated to form ATP.
Which of the following is least stable? A) starch B) ATP C) glucose D) AMP E) cellulose
ATP
The energy for building a potassium gradient across the outer cell membrane of a nerve cell is provided by _________ A) electron flow B) ATP C) NADH D) the ATP synthase E) a sodium gradient
ATP (explanation: Sodium and potassium gradients across a nerve cell membrane are generated by the Na+/K+ pump that requires ATP energy to pump both ions against their concentration gradients. The only place where an ATP synthase is found, and where electron flow builds a gradient (of protons, not sodium) in eukaryotes is in chloroplasts or mitochondria. NADH provides the energized electrons for mitochondrial electron transport and building of a proton (not sodium) gradient.)
Hint 1. Energy conversion from one form to another in the light reactions The light reactions convert one form of energy into the chemical energy of ATP molecules. Think about the source of this energy and about what is needed to make ATP molecules. Hint 2. Which energy sources produced in the light reactions will be used by the Calvin cycle? Which of the following transfer energy from the light reactions to the Calvin cycle? select all that apply: light G3P ATP NADPH
ATP NADPH
Which statement is FALSE? First exclude the four that are correct. While performing photosynthesis during the day, the chloroplasts of a green leaf produce A) ATP to be used in the Calvin cycle. B) ATP as an energy source for the roots of the plant. C) sugars for the green leaf's cellular respiration at night. D) sugars as an energy source for the roots of the plant. E) sugars to fuel the growth of the plant.
ATP as an energy source for the roots of the plant.
Prokaryotes carry out all processes below except A) active transport of substances across membranes. B) movement work using motor proteins. C) ATP formation in fermentation. D) ATP formation in mitochondria. E) energy-dependent synthesis of large molecules.
ATP formation in mitochondria (explanation: Prokaryotes do not have mitochondria and therefore D is the answer to this prompt. All cells, including prokaryotes, do carry out the three types of cellular work, i.e., transport of substances across membranes, use of motor proteins to induce movement, and synthesis of large molecules. Prokaryotes make all their ATP in the cytosol where fermentation takes place.)
Which statement about ATP is FALSE? First exclude the four statements that are correct. A) ATP powers transport work, chemical work, and movement work. B) ATP provided by mitochondrial electron transport energizes C-H bond formation in the citric acid cycle. C) ATP provided by photosynthetic electron transport energizes C-H bond formation in the Calvin cycle. D) Most regeneration of ATP from ADP and phosphate in animal cells occurs in the mitochondria. E) ATP is very unstable.
ATP provided by mitochondrial electron transport energizes C-H bond formation in the citric acid cycle.
Eukaryotic cells build gradients of either H+, K+, or Na+ across which membranes? A) Only across thylakoid membranes B) Only across inner mitochondrial membranes C) Only across the outer cell membrane D) Across both thylakoid membranes and inner mitochondrial membranes, but not across the cell membrane E) Across thylakoid membranes, inner mitochondrial membranes, and the outer cell membrane
Across thylakoid membranes, inner mitochondrial membranes, and the outer cell membrane (explanation: Gradients across membranes can be found in the chloroplasts of plants and algae (proton gradient across the thylakoid membranes of chloroplasts), mitochondria of all eukaryotes (proton gradient across the the inner mitochondrial membranes), and the outer cell membrane of various eukaryotes (sodium and potassium gradients across the outer cell membrane). Thus E is the correct answer.)
Cells release energy from food molecules. Deduce which of the steps below represent(s) a change from one form of energy to another? A) Use of energy-rich electrons to build up a proton gradient B) Use of the proton gradient to drive ATP formation C) Use of an uncoupling protein to generate heat D) All of the above E) Only A and B
All of the above (explanation: The movement of energized electrons through the mitochondrial electron transport chain pumps protons from the matrix into the intermembrane space and converts the energy of energized electrons into a proton gradient. The flow of the protons from high concentration in the intermembrane space back into the matrix, when coupled to the turning of the ATP synthase turbine, converts the energy of the proton gradient to the energy of ATP. Similarly, the flow of protons from high concentration in the intermembrane space back to low concentration in the matrix through the uncoupling protein converts the energy of the proton gradient to heat energy. In other words, D is the correct answer!)
Which feature or process occurs in Archaea? A) Photosynthesis in chloroplasts B) Protein modification in a Golgi apparatus C) Formation of some ATP in the citric acid cycle D) An outer cell membrane E) mRNA synthesis in a nucleus
An outer cell membrane (explanation: Archaea are prokaryotes and thus do not have organelles such as chloroplasts (answer A) or mitochondria in which the citric acid cycle operates (answer C). Although they do have DNA and produce mRNA, prokaryotes do not have a nucleus that houses DNA in a space surrounded by a membrane (answer E). Prokaryotes also lack an endomembrane system of which the Golgi apparatus is a part (answer C). What Archaea (and all prokaryotes and eukaryotes) do possess is an outer cell membrane that controls what enters and leaves the cell.)
Describe how photosynthesis and cellular respiration fit into the chemical cycle that connects producers and consumers.
At the heart of the exchange between producers & consumers lies a cycle of chemical reactions: between fuel molecules with bonds that have loosely held electrons that release energy and molecules with bonds that have electrons held tightly by oxygen atoms
Complete the sentence: The ATP synthase turbine accumulates protons and builds a proton gradient utilizes a proton gradient enables facilitated diffusion of protons A and C B and C
B and C (explanation: The ATP synthase plays no role in building the proton gradient - on the contrary, it utilizes and thereby diminishes that gradient by allowing protons to flow (by facilitated diffusion, or passive transport, through the ATP synthase channel) from the inner thylakoid space into the stroma. As the protons diffuse through the ATP synthase, the energy from the proton gradient is converted to the energy of ATP. Thus E is the correct answer.)
What feature makes carbohydrates and fats energy sources?
Both have a lot of bonds with loosely held electrons.
The final energy-rich product of photosynthesis is ________ and the energy source obtained by consumers from their food is ________.
C-H bonds of sugars; C-H bonds of food molecules
What is the formula of the molecule made by adding one fructose to a molecule of lactose?
C18H32O16 (Explanation: Fructose is a hexose monosaccharide; lactose is a disaccharide made of the two hexoses glucose and galactose. The lactose molecule was formed by dehydration synthesis of two hexoses: 2 x C6H12O6 - H2O = C12H22O11. Adding another hexose (fructose) to lactose in dehydration synthesis can be described as C12H22O11 + C6H12O6 - H2O = C18H32O16)
Summary: Advantages of C4 and C3 Plants: Advantage of C3 plants: C3 plants need ____ ATP energy to fix CO2 Advantage in _____ sunny, but _______ climates
C3 plants need less ATP energy to fix CO2 Advantage in less sunny, but moister climates
Summary: Advantages of C4 and C3 Plants: Advantage of C4 plants: C4 plants fix CO2 with leaf pores (stomates) less widely open & need _____ water Advantage in ____ and _____ climates
C4 plants fix CO2 with leaf pores (stomates) less widely open & need less water Advantage in dry and sunny climates
Four of the statements below are false. Which one is TRUE. A) C3 plants are able to fix CO2 with their stomates (leaf pores) less widely open than C4 plants. B) C3 plants are more productive in dry climates than C4 plants. C) C4 plants need more water than C3 plants. D) C4 plants need more energy (sunlight) to make sugars than C3 plants. E) C3 plants need more ATP than C4 plants to fix CO2.
C4 plants need more energy (sunlight) to make sugars than C3 plants (explanation: As we established in the previous two questions, answer D is a true statement - C4 photosynthesis requires additional ATP and more sunlight compared to C3 photosynthesis to make the same amount of sugar as a C3 plant. Answer E falsely states that C3 plants need more ATP to fix a CO2 molecule through photosynthesis. Answer A is false because it is C4 plants and not C3 plants that can fix the same amount of CO2 with their leaf pores open to a lesser extent. Thus C4 plants need less (not more) water and can be more productive in a dry climate compared to C3 plants, which makes answers B and C false as well.)
inputs and outputs what goes into the Calvin cycle? ____________ ____________ ____________
CO2 ATP NADPH
Photosynthesis outputs & inputs Carbon source: Carbon product: H (electron + H+) source: Ultimate energy source: Final energy-rich product:
CO2 Sugar (C-H bonds) Water Sunlight Sugar (C-H bonds
Inputs and outputs what comes out of the Citric Acid Cycle? ______ & ________ ______________ ______________
CO2 & CoA NADH A little ATP
Which is correct about CO2 released in cellular respiration? A) CO2 is released when glucose is converted to pyruvate in the mitochondrial matrix. B) CO2 is formed when oxygen accepts electrons from the mitochondrial electron transport chain. C) CO2 is what is left from the glucose after removal of H (electrons and H+). D) CO2 is formed by extraction of electrons from water. E) CO2 is released in the Calvin cycle.
CO2 is what is left from the glucose after removal of H (electrons and H+).
A and C (The photosystems contain chlorophyll.)
Chlorophyll can be found in _____.
Describe how a proton gradient is built across the inner mitochondrial membrane by active transport and is later utilized by passive transport.
Electron transport builds a proton gradient across an inner membrane. Protons (H+) flow through the ATP synthase from high to low concentration. The ATP synthase turbine utilizes the energy of the proton gradient to form ATP. Both photosynthesis and mitochondrial respiration form ATP in this way.
The ATP synthase turbine utilizes the proton (H+) gradient to make ATP.
Electron transport builds a proton gradient across an inner membrane. Protons (H+) flow through the ATP synthase from high to low concentration. The ATP synthase turbine utilizes the energy of the proton gradient to form ATP. Both photosynthesis and mitochondrial respiration form ATP in this way.
Summary for exam: The ATP synthase turbine utilizes the proton (H+) gradient to make ATP. Electron transport _______ a proton gradient by pumping H+ from low concentration in the stroma to ever-higher concentration in the internal thylakoid space. Protons (H+) flow through the ATP synthase from high to low concentration back into the stroma. The ATP synthase turbine _________ the energy of the proton gradient to form ATP in the stroma.
Electron transport builds a proton gradient by pumping H+ from low concentration in the stroma to ever-higher concentration in the internal thylakoid space. Protons (H+) flow through the ATP synthase from high to low concentration back into the stroma. The ATP synthase turbine utilizes the energy of the proton gradient to form ATP in the stroma.
Narrate the path of water, oxygen, and electrons through the steps of photosynthesis and of cellular respiration.
Electrons for the photosynthetic electron transport chain come from water --> then become part of C-H bonds of sugars & later form water again. Photosynthesis splits water into electrons, protons, and O2, --> O2 picks up the electrons again at the end of the mitochondrial electron transport chain.
Deduce which took place in the ABSENCE OF molecular oxygen (O2) or ozone (O3). A) Evolution of organisms from the ocean to the terrestrial (land) habitat B) Evolution of large, multi-cellular organisms C) Evolution of prokaryotes that use fermentation D) Evolution of ATP formation in mitochondria E) Evolution of plants and animals
Evolution of prokaryotes that use fermentation (explanation: The movement of life from the ocean onto land is thought to have required development of the ozone layer that blocks the most damaging ultraviolet radiation from reaching the surface of the earth. In addition, multi-cellular organisms (including plants and animals), with large cells that carry out many functions simultaneously, rely on the production of lots and lots of ATP to fuel all these processes. These large organisms can only be supported by aerobic cellular respiration, with oxygen as the final electron acceptor at the end of the mitochondrial electron transport chain. With oxygen, lots and lots of ATP can be produced from each glucose molecule, while only a tiny bit of ATP can be produced through glycolysis and fermentation. Since the latter two processes occur in the absence of oxygen, "evolution of prokaryotes that use fermentation" is the correct answer.)
Find the blue circles with numbers 1-3 in the diagram above: Sunlight ___________ ______________ of chlorophyll that leave chlorophyll and are continuously replaced by electrons from water Water is split into electrons, H+, and oxygen The energized electrons flow through the photosynthetic __________ ___________ __________ (line of orange arrows) Pump H+ from the stroma into the thylakoid space (solid red arrow); Next, H+ flowing through the ATP synthase turn the turbine (dashed red arrows) Energizes ATP formation by the ATP synthase. Light energizes electrons again for loading ___________ __________ (line of orange arrows) NADPH and ATP go to the Calvin Cycle to make sugar.
Find the blue circles with numbers 1-3 in the diagram above: Sunlight energizes electrons of chlorophyll that leave chlorophyll and are continuously replaced by electrons from water Water is split into electrons, H+, and oxygen The energized electrons flow through the photosynthetic electron transport chain (line of orange arrows) Pump H+ from the stroma into the thylakoid space (solid red arrow); Next, H+ flowing through the ATP synthase turn the turbine (dashed red arrows) Energizes ATP formation by the ATP synthase. Light energizes electrons again for loading onto NADP+ (line of orange arrows) NADPH and ATP go to the Calvin Cycle to make sugar.
Respiration outputs & inputs Carbon source: Carbon product: H (electron + H+) source: Ultimate energy source: Final energy-rich product:
Food (C-H bonds) CO2 Food (C-H bonds) Food (C-H bonds) ATP
inputs and outputs what comes out of the Calvin cycle? ____________ ____________ ____________
G3P Sugar (to make glucose) ADP + P NADP+
Which is NOT energized by phosphorylation? First exclude the four processes that are energized by phosphorylation. A) the sodium/potassium pump in the outer cell membrane B) H+ transport from low H+ concentration in the matrix to high H+ concentration in the intermembrane space by mitochondrial electron transport C) transport of vesicles by motor proteins D) calcium movement into the sarcoplasmic reticulum (SR) during muscle relaxation E) formation of ATP
H+ transport from low H+ concentration in the matrix to high H+ concentration in the intermembrane space by mitochondrial electron transport
Which bond or molecule does NOT contain high-energy electrons? First exclude the four bonds or molecules that do contain high-energy electrons. A) food molecules B) C-H bonds C) sugars D) H-O-H E) proteins
H-O-H (Explanation: The source of high-energy electrons for respiration is any molecule with C-H bonds, like sugars, proteins, and other food molecules. Water does not contain any high-energy electrons. Water is merely the source of electrons that become energized by sunlight and enter the photosynthetic electron transport chain in the chloroplast. Some of these electrons will eventually work their way into the process of respiration. Cellular respiration forms water when oxygen picks up electrons at the end of the mitochondrial electron transport chain.)
inputs and outputs what goes into light reactions? ____________ ____________ ____________ ____________
H2O Sunlight ADP + P NADP+
Hemoglobin __________ O2 in the lungs and __________ O2 in the muscle; the binding capacity of hemoglobin for O2 is _________ in the lungs and _________ in the muscle region when those muscles are being used.
Hemoglobin binds O2 in the lungs and releases O2 in the muscle; the binding capacity of hemoglobin for O2 is high in the lungs and low in the muscle region when those muscles are being used.
D
Identify a thylakoid.
A
Identify the chloroplast.
E
Identify the stroma.
Part B - Inputs and outputs of the Calvin cycle From the following choices, identify those that are the inputs and outputs of the Calvin cycle. Drag each item to the appropriate bin. If the item is not an input to or an output from the Calvin cycle, drag it to the "not input or output" bin.
In the Calvin cycle, the energy outputs from the light reactions (ATP and NADPH) are used to power the conversion of CO2 into the sugar G3P. As ATP and NADPH are used, they produce ADP and NADP+, respectively, which are returned to the light reactions so that more ATP and NADPH can be formed.
Which is FALSE? First exclude the four correct answers. A) The leaves are only a small part of the plant and must produce enough energy-rich sugars to support all non-green parts like roots or flowers. B) Only when overall photosynthetic activity is greater than overall respiration activity of the whole plant can the plant accumulate biomass and grow. C) Sugar produced in photosynthesis must support the plant's energy needs both day and night. D) Leaves perform more photosynthesis than respiration because they don't have mitochondria. E) In trees that drop their leaves over the winter, some sugar produced in one year is stored in stems or roots and fuels the production of new leaves in the next year
Leaves perform more photosynthesis than respiration because they don't have mitochondria.
Hint 3. What is the role of light in the light reactions? The term "light reactions" implies that light plays some role in this stage of photosynthesis. Which of the following statements correctly describes a role of light in the light reactions? Which of the following statements correctly describes light's role? A) Light supplies the energy to remove electrons from water and to transport those electrons to NADP+. B) Light provides the atoms that are needed to convert ADP to ATP. C) Light supplies the electrons that are needed to reduce NADP+ to NADPH. D) Light energy is used to fix CO2 into sugar.
Light supplies the energy to remove electrons from water and to transport those electrons to NADP+.
inputs and outputs What comes out of mitochondrial electron transport? ______________ ______________ ______________
NAD+ H2O Lots of ATP
inputs and outputs what goes into mitochondrial electron transport? ______________ ______________ ______________
NADH O2 Lots of ADP + P
Which statement about hydrogen (H) atoms in photosynthesis and respiration is FALSE? First exclude the four correct statements. A) Photosynthesis and respiration both use H shuttles. B) H is removed from water to make sugars in photosynthesis; H removed from sugars is combined with oxygen to form water in respiration. C) NADH is used in photosynthesis; NADPH is used in respiration. D) The O-H bond has partial electrical charges; the C-H bond consists of electrons shared evenly between the partner atoms. E) While the O-H bond cannot be used to release energy, the C-H bond can be used to release energy.
NADH is used in photosynthesis; NADPH is used in respiration.
Which does NOT represent a state of high energy? (Hint: First exclude the four energy-rich states.) A) NADH B) NADP+ C) ATP D) a calcium gradient across a membrane E) a proton (H+) gradient across a membrane
NADP+ (explanation: A gradient of substance across a membrane (with a low concentration on one side and a high concentration on the other side) represents a store of energy that can be utilized for an important function (e.g., muscle function in answer D & ATP formation in answer E). NADH (answer A) is the shuttle for energized electrons and thus contain energy. ATP, with its multiple negative phosphate groups, contains pent-up energy to fuel energy-requiring cellular work. The empty NADP+ shuttle is thus the only substance (answer B) that does not contain energy or represent a state of high energy. Only after adding energized electrons, and becoming NADPH, is a substance formed that contains energy.)
inputs and outputs what comes out of the light reactions? ____________ ____________ ____________
O2 ATP NADPH
Predict the relative rate of leaf photosynthesis compared to leaf respiration over the lifespan of a green leaf. A) Overall photosynthesis rates and respiration rates of a leaf should be the same. B) Overall photosynthesis rates of a leaf should be higher. C) Overall respiration rates of a leaf should be higher.
Overall photosynthesis rates of a leaf should be higher. (explanation: The process of cellular respiration generates ATP to fuel all cellular work in every cell of the plant. Photosynthesis must supply sugars to sustain not only the plant's leaves, but every non-photosynthetic cell throughout the entire plant. In addition, the process of photosynthetic sugar production only occurs during daylight, whereas cellular respiration takes place continuously day and night. Thus the rate of photosynthesis should far exceed the rate of respiration over the lifespan of a leaf. Moreover, photosynthesis provides energy to soil microbes that provide water, nutrients, and defense to the plant as we discussed earlier. And photosynthesis also fills energy stores in roots and tubers that help many plants survive stressful seasons (sometimes without leaves during winter or a period of drought), fueling new growth when conditions become favorable again.)
Which statement is FALSE? First exclude the four statements that correctly describe the involvement of oxygen in photosynthesis. A) Oxygen is a by-product of photosynthesis. B) Oxygen is required for sugar production in the Calvin cycle. C) Oxygen is formed from water. D) Oxygen formed in the chloroplast could be used in the mitochondria of the same cell. E) Leaves require light to produce oxygen.
Oxygen is required for sugar production in the Calvin cycle. ( explanation: The electrons that flow through the photosynthetic electron transport chain are obtained by water splitting powered by sunlight: each H2O is split into two electrons, two protons, and oxygen. Oxygen is a by-product of the light reactions of photosynthesis but does not participate in sugar production in the Calvin cycle. Oxygen generated by photosynthesis can either serve to accept electrons in the mitochondria of any living plant cell or may be released into the atmosphere.)
Which correctly describes the relationship between photosynthesis and respiration? A) Photosynthesis only occurs in plants and respiration only occurs in animals. B) ATP molecules are produced in photosynthesis and used up in respiration. C) Respiration stores energy in energy-rich, carbon-based molecules, while photosynthesis releases energy from energy-rich carbon-based molecules. D) Photosynthesis stores energy in energy-rich, carbon-based molecules, while respiration releases energy from energy-rich carbon-based molecules. E) Both photosynthesis and respiration consume more ATP than they produce.
Photosynthesis stores energy in energy-rich, carbon-based molecules, while respiration releases energy from energy-rich carbon-based molecules.
_________ are piled up in the inner thylakoid space like water behind a dam and flow back through the ATP synthase from high to low H+ concentration.
Protons (H+) are piled up in the inner thylakoid space like water behind a dam and flow back through the ATP synthase from high to low H+ concentration.
The mitochondrial uncoupling protein consists of a proton channel portion but does not have a turbine for making ATP. _________ flow through the uncoupling protein channel along their concentration gradient without making _______ . All energy is released as heat.
Protons flow through the uncoupling protein channel along their concentration gradient without making ATP. All energy is released as heat.
Find the only statement that does NOT apply to both photosynthesis and cellular respiration. First exclude the four statements that apply to both photosynthesis and respiration. A) High-energy electrons pass through an electron transport chain. B) Electrons give up energy while passing through an electron transport chain. C) Electrons provide the energy to move protons from low to high concentration. D) Flow of protons through an ATP synthase converts the potential energy of a proton gradient to ATP. E) The energy for ATP formation comes from energy-rich bonds of sugars.
The energy for ATP formation comes from energy-rich bonds of sugars. (explanation: In both photosynthesis and aerobic cellular respiration, A) energized electrons travel through an electron transport chain and B) lose a tiny bit of energy with each transfer from carrier to carrier. This electron transport establishes a proton shuttle that moves protons from one side of a membrane to the other side of a membrane (from low to high concentration. D) The energy of this proton gradient is converted into ATP energy (protons flowing through the ATP synthase turn this turbine and force a third phosphate group onto ADP to form ATP). Sugars provide energized electrons to feed into the mitochondrial electron transport chain in aerobic cellular respiration but not in photosynthesis. In photosynthesis, sunlight provides the energy for electron flow, building of a proton gradient, and ATP formation, which makes E the incorrect answer you are trying to find.)
List the overall inputs and outputs of photosynthesis and cellular respiration.
The inputs and outputs of photosynthesis and respiration are connected no matter whether you are looking at a chloroplast and a mitochondrion in the same cell, at a single plant and a single animal, or at all producers and consumers on the earth.
Which is correct? A) The light reactions provide the Calvin cycle with oxygen, and the Calvin cycle provides the water for the light reactions. B) The light reactions provide ATP and NADPH, and the Calvin cycle provides sugar for the light reactions. C) The light reactions provide the CO2 that is converted to sugar in the Calvin cycle. D) The light reactions provide ATP and NADPH to the Calvin cycle.
The light reactions provide ATP and NADPH to the Calvin cycle.
Which does NOT involve electrons as DIRECT participants? First exclude the four processes in which electrons are dropped off, picked up, or power the process. A) Movement of protons from the matrix across the inner mitochondrial membrane. B) Turning the ATP synthase to generate ATP from ADP and phosphate. C) Formation of water from O2. D) Movement of protons into the intermembrane space. E) Regeneration of NAD+ from NADH.
Turning the ATP synthase to generate ATP from ADP and phosphate. (explanation: Energized electrons provide the energy to shuttle protons from the matrix space across the inner mitochondrial membrane into the intermembrane space of the mitochondria (answers A & D are correct and thus not the answer you are trying to find). Electrons that have moved all the way through the mitochondrial electron transport chain are picked up by O2, which then adds protons to form water (answer C is correct and thus not the answer you are trying to find). Energized electrons are transferred to the mitochondrial electron transport chain by the NADH shuttle, which is regenerated to NAD+ when it drops off the electrons (answer E is, again, correct, and not the answer you are trying to find). The only answer that does not involve electrons as direct participants is B - the ATP synthase is directly powered by the flow of protons - but not electrons - to make ATP from ADP and a phosphate group.)
Which statement about transport and use of oxygen in humans is FALSE? First exclude the four true statements. A) Oxygen for cellular respiration is taken up by the lungs. B) Hemoglobin transports oxygen from the lungs to body cells. C) Oxygen serves as the final electron acceptor in mitochondria. D) Water is converted to oxygen in mitochondria. E) High CO2 levels decrease the oxygen-binding capacity of hemoglobin.
Water is converted to oxygen in mitochondria.
E (The Calvin cycle occurs in the stroma.)
Where does the Calvin cycle occur?
Predict the features of fast-twitch & slow-twitch muscle fibers (for the question on myoglobin, go back to your notes from Respiration): Which.. have more mitochondria? have more blood supply / capillary density? have less myoglobin? have greater fatigability (get tired faster)? are fast-glycolytic or slow-oxidative? are aerobic or anaerobic?
Which have more mitochondria? Slow-twitch have more blood supply / capillary density? Slow-twitch (needs O2 supply delivered by the blood stream) have less myoglobin? Fast-twitch (myoglobin serves to store O2, which is not needed for fermentation) have greater fatigability (get tired faster)? Fast-twitch get tired more quickly. are fast-glycolytic or slow-oxidative? Fast twitch = fast & use only glycolysis to make ATP; slow twitch = slow & use oxidative phosphorylation in mitochondria to make ATP. are aerobic or anaerobic? Slow-twitch use aerobic cellular respiration; fast-twitch use anaerobic cellular respiration (=fermentation)
E (ATP synthase phosphorylates ADP.)
Which of these phosphorylates ADP to make ATP?
A (Photosystem II splits water into 1/2 O , H , and e-)
_____ splits water into 1/2 O2, H , and e- .
What is NOT needed to form water in mitochondria? First exclude all that are needed for water formation. A) protons B) electrons C) oxygen D) a place for oxygen to bind to the inner mitochondrial membrane E) a place for protons to bind to the inner mitochondrial membrane
a place for protons to bind to the inner mitochondrial membrane
The oxygen consumed during cellular respiration is a DIRECT participant in what process? Exclude the four processes that are indirectly linked to oxygen consumption in cellular respiration. A) phosphorylation of ADP to form ATP B) accepting electrons from sugars in glycolysis C) accepting electrons at the end of the mitochondrial electron transport chain D) accepting electrons from the components of the citric acid cycle E) removing electrons from NADH
accepting electrons at the end of the mitochondrial electron transport chain
Which is NOT involved in building a proton gradient across the thylakoid membrane? A) alternation of electron carriers that do or don't transport protons B) H+ pick-up outside the thylakoids by an electron carrier C) H+ drop-off inside the inner thylakoid space by an electron carrier D) an ATP-fueled pump E) release of H+ during water splitting
an ATP-fueled pump (explanation: An electron carrier (Pq) picks up electrons and must add H+ to be able to transport these electrons. It picks up H+ from the stroma side and carries these H+ along with the electrons to the next electron carrier in line. This next carrier transports only electrons but no H+. The drop-off point for the electrons is on the inner side of the thylakoids and the H+ are released into this inner thylakoid space. This alternation of electron carriers that either must or cannot carry H+ along with the electrons, and the location of the pick-up and drop-off points, operates a light-driven H+ shuttle across the thylakoid membrane and builds a proton gradient, as described by answers A, B, and C. This is a case where active transport (of H+) is energized by electrons rather than by an ATP-fueled pump. Release of two H+ directly into the thylakoid space every time a water molecule is split further contributes to building this H+ gradient (answer E). A third contributor to building the H+ gradient is removal of H+ from the stroma each time electrons are transferred to NADP+, which also picks up H+ to form NADPH (blue circle number 3). The correct answer is D, since there is no ATP-fueled pump in the thylakoid membrane that builds a proton gradient. On the contrary, there is an ATP synthase that allows H+ to flow from high concentration in the inner thylakoid space out into the stroma (by passive transport), while transforming the energy of the H+ gradient into energized ATP molecules.)
Which organisms do NOT use NADH to deliver electrons into a mitochondrial electron transport chain? A) Bacteria and archaea B) Animals that maintain a constant body temperature C) Plants D) Eukaryotic algae E) Animals that do not maintain a constant body temperature
bacteria and archaea (explanation: The answer to the previous question stated that prokaryotes (bacteria and archaea) do NOT have organelles. Since they do not have mitochondria, they cannot deliver electrons into a mitochondrial electron transport chain. All eukaryotes (e.g., animals, plants, and algae) do have mitochondria and use NADH to deliver electrons into the mitochondrial electron transport chain.)
Why do plants use the ATP made by ATP synthase to produce sugars?
because ATP is too unstable to store for more than a very short time
Every energy transformation leads to a loss of usable energy as heat (=unusable energy) Humans generate much more heat than alligators. Predict what this is due to: A) a greater number of energy transformations per minute in humans. B) a higher percentage of energy loss per transformation in humans. C) Both A and B
both A and B (explanation: Not only are there more energy transformations per unit of time in the cells of humans, but the energy transformations in human cells are also less efficient than those in alligator cells. This is particularly true of the many mitochondrial powerhouses of the cell. The generation of heat in their bodies helps mammals (and also birds) maintain a high body temperature when air temperatures are cold. The cost for this is that humans must eat a lot more than alligators.)
ATP is produced by
both mitochondria and chloroplasts, but not by transport proteins in the cell membrane.
Movement of protons (H+) from the chloroplast stroma into the inner thylakoid space _________, and movement of protons (H+) through the ATP synthase ______.
builds a proton gradient; utilizes a proton gradient
Carbohydrates are formed in photosynthesis from
carbon dioxide and water.
Which molecule could NOT be the dietary source of CO2 exhaled by you? First exclude the four that could be the source of the exhaled CO2. A) cellulose B) starch C) fructose D) glucose E) fat
cellulose
Which of these is a polysaccharide?
cellulose (Cellulose is a carbohydrate composed of many monomers.)
_____ is the most abundant organic compound on Earth.
cellulose (Cellulose, a component of plant cell walls, is the most abundant organic compound found on earth.)
The polysaccharides ________________ occur in plants, while ___________ occur(s) in animals.
cellulose and amylose; glycogen (Explanation: The slides on Carbohydrates list which of these polysaccharides occur in plants and animals.)
Which plant product is difficult to break down into monosaccharides for biofuel production? A) sucrose from C3 plants B) starch from C4 plants C) starch from C3 plants D) cellulose from C3 plants E) sucrose from C4 plants
cellulose from C3 plants (explanation: Sucrose, regardless what photosynthetic organism it comes from, is easy to break down into its two monosaccharide building blocks glucose and fructose. Starch, regardless of its origin, is also easy to break down into its monosaccharides (glucose). Therefore D is the correct answer: Any cellulose is hard to break down (requiring the action of a number processes to extract the cellulose from the other components of cell walls of several enzymes to release the glucose monomers from this large polysaccharide).
Brown fat tissue
converts most of the energy of food molecules to heat
The ATP synthase turbine A) uses ATP to build a proton gradient by moving protons from low to high concentration. B) utilizes a proton gradient for the purpose of adding protons to ADP to produce ATP. C) converts the energy of a proton gradient to energy usable for cellular work.
converts the energy of a proton gradient to energy usable for cellular work (explanation: Yes, protons are pumped from low to high concentration to build a proton gradient - but by electron transport and not by the ATP synthase. Yes, the ATP synthase uses a proton gradient - but not to add protons to ADP but to add a third phosphate group to ADP. The ATP synthase does indeed use the energy of the protons flowing from high to low concentration to form ATP that can be used to fuel cellular work (answer C).)
Ethanol's Possible Future as a Biofuel: 3) Cellulosic ethanol Cellulose is ______ to convert to hexoses.
difficult
Ethanol from corn starch starch is ________ to digest to hexoses
easy (HOWEVER: Annual crop, high input of fertilizer (produced with fossil fuels); only small portion of plant mass used)
Ethanol from sugarcane Sucrose is ______ to convert to hexoses.
easy (Seven harvests of cane before replanting is necessary. Cane waste is burned for power & heat. HOWEVER: food versus fuel conflict)
Deduce which does NOT represent a state of high energy. A. electrons loaded onto NADPH B. the H+ gradient across the thylakoid membrane C. electrons in the water molecule D. the ATP formed E. electrons excited by sunlight
electrons in the water molecule (explanation: The model answer to the question before last restated that oxygen holds on tightly to electrons in the water molecule, and that water, therefore, is not a fuel or energy source. This makes C the answer to this NOT question, since water does not represent a state of high energy. All the other options do represent states of high energy, including the energized electrons carried by the NADPH shuttle, the proton gradient between the inside of the thylakoid membranes and the stroma, ATP (as the energy currency of the cell), and electrons that are energized by photons of light.)
Carbohydrates are burned in cellular respiration for the purpose of producing
energy for the cell.
All processes below are directly or indirectly related to ATP production in mitochondria. Which DIRECTLY turns the ATP synthase turbine in mitochondria? A) flow of H+ along its concentration gradient from the intermembrane space to the matrix. B) transfer of electrons to oxygen as the final electron acceptor. C) loading of electrons from NADH into the mitochondrial electron transport chain. D) removal of H (electrons and H+) from C-H bonds of energy-rich food molecules in glycolysis. E) removal of H (electrons and H+) from C-H bonds of energy-rich food molecules in the citric acid cycle
flow of H+ along its concentration gradient from the intermembrane space to the matrix.
________________ is produced in plants, while ___________ is produced in animals. A) glycogen; amylopectin B) starch; amylose C) cellulose; glycogen D) glycogen; starch E) cellulose; starch
glycogen; starch (explanation: The polysaccharide starch, including the two different starches amylopectin and amylose, are made from glucose monomers by plants but not by animals. Plants also use glucose monomers to make the polysaccharide cellulose as a major component of cell walls. Animals make glycogen - but not starch - as their storage polysaccharide for glucose monomers (especially in liver and muscle cells).)
Which is NOT true for the C-H bond? First exclude the four statements that are true. The C-H bond A) is a bond with electrons shared evenly between the partner atoms B) is found in fats, phospholipids, and carbohydrates C) has less energy that can be released than a C=O bond D) can be burned to release energy E) can react with oxygen to form carbon dioxide and water
has less energy that can be released than a C=O bond
All energy entering an ecosystem is eventually converted to what form of energy in the end?
heat (Explanation: Energy changes form several times. Producers convert sunlight to energy-rich carbon-based molecules that provide energy for ATP formation in cellular respiration. ATP powers all cellular work, which releases energy as heat. All energy from sunlight that enters an ecosystem is eventually converted to unusable heat energy. Several lecture slides on Respiration illustrate this point.)
Picture a cow eating grass. Most of the sun's energy absorbed by the grass is eventually converted to what form?
heat in the environment
The energy for building a proton gradient is provided by A) the ATP synthase protein. B) the electron carriers of the electron transport chain. C) high energy electrons (derived from food molecules) that flow through the electron transport chain. D) electrons (provided by oxygen) that flow through the electron transport chain.
high energy electrons (derived from food molecules) that flow through the electron transport chain (explanation: The ATP synthase utilizes the energy of the proton gradient, but does not build it. The electron carriers do not have any energy - they simply pick up and drop off energized electrons. Since this is a mitochondrial electron transport chain, the energized electrons from food molecules provide the energy for transporting protons from the matrix (the inner-most, fluid filled space within the inner membrane) to the intermembrane space (between the outer and inner membranes of the mitochondrion) - so, C is the correct answer. Oxygen picks up electrons at the end of the electron transport chain; it does not provide energized electrons to the mitochondrion. )
NAD+ can be loaded with high-energy electrons in which reaction(s) or location(s)? A) Only at the end of the mitochondrial electron transport chain B) Only in the citric acid cycle C) Only at the end of the photosynthetic electron transport chain D) Only in glycolysis E) In the citric acid cycle and in glycolysis
in the citric acid cycle and in glycolysis (explanation: NAD+ picks up energized electrons in both glycolysis and the citric acid cycle (answer E is correct). It is oxygen (O2) that picks up electrons at the end of the mitochondrial electron transport chain. And it is NADP+ and not NAD+ that picks up energized electrons at the end of the photosynthetic electron transport chain in the chloroplast.)
Where are electron transport chains found in plant cells?
in the thylakoid membranes of chloroplasts and in the inner membranes of mitochondria
Predict in which environments C3 plants versus C4 plants should each be most successful. C3 plants will be most successful in __________ environments, and C4 plants will be most successful in __________ environments. A) sunnier and drier; less sunny but moister B) less sunny but moister; sunnier and drier C) less sunny but drier; sunnier and moister D) sunnier and moister; less sunny but drier
less sunny but moister; sunnier and drier (explanation: Given the functional differences between C3 and C4 plants, C3 plants tend to be more successful and competitive in locations that are moister (since C3 plants open their leaf pores more widely and lose more water) and shadier (since they need less ATP and less sunlight). On the other hand, C4 plants require more ATP and more sunlight to carry out photosynthesis, but can afford to open their stomates less widely (and lose less water) because they can fix CO2 much more efficiently; C4 are therefore more competitive and thrive in sunnier and drier locations.)
glucose + glucose —> _____ by _____.
maltose + water ... dehydration synthesis (Maltose is the disaccharide formed when two glucose molecules are linked by dehydration synthesis.)
The following statement compares different starches: Because it is branched and can be broken down to ________ by multiple enzymes at the same time, _________ is digested more quickly than _________.
monosaccharides; amylopectin; amylose
Which is a source of lactose? First exclude all incorrect answers. A) plant cell walls B) glycogen C) table sugar D) starch E) none of the options given
none of the options given
Compare the photosynthetic light reactions with the Calvin cycle: Which CONSUME(S) ATP? A) both the light reactions and the Calvin cycle B) neither the light reactions nor the Calvin cycle C) only the transport of protons across the thylakoid membrane in the light reactions D) only the Calvin cycle E) only the energy-consuming splitting of water in the light reactions
only the Calvin cycle
The reaction of oxygen (O2) with which of the following releases energy for ATP formation? A) Hydrogen gas (H2), hydrocarbons (as in gasoline), paper (cellulose), electrons (plus H+) at the end of the mitochondrial electron transport chain B) only hydrocarbons (as in gasoline), paper (consisting of cellulose), and electrons (plus H+) at the end of the mitochondrial electron transport chain C) only paper (consisting of cellulose) and electrons (plus H+) at the end of the mitochondrial electron transport chain D) only electrons (plus H+) at the end of the mitochondrial electron transport chain
only electrons (plus H+) at the end of the mitochondrial electron transport chain
Formation of water from oxygen occurs
only in cellular respiration.
Compare the photosynthetic light reactions with the Calvin cycle: Where is NADPH PRODUCED?
only in electron transport in the light reactions (explanation: he photosynthetic electron transport chain (light reactions) adds electrons to NADP+ and produces NADPH. The Calvin cycle uses NADPH +and produces NADP . Sugars are formed in the Calvin cycle by forming new C-H bonds with electrons provided by NADPH; NADPH is consumed - not produced -in the Calvin cycle. Extraction of electrons from sugars only occurs in cellular respiration, not in photosynthesis.)
Sunlight energizes electrons that pass into an electron transport chain where they help move ______ from low to high concentration. The electrons are loaded onto ______ at the end of the photosynthetic electron transport chain.
protons (H+); NADP+ (explanation: Electrons flowing down the electron transport chain help move protons from low concentration in the stroma to high concentration in the inner thylakoid space. Electrons running through the electron transport chain pick up protons and then drop the protons off again. Pick-up takes place outside of thylakoids in the stroma, while the drop-off spot is on the inside of the thylakoids. This way, protons are accumulated inside the thylakoids every time electrons run through the electron transport chain. After dropping off the protons, the electrons receive a second boost from sunlight in the NADPH- producing photosystem that loads electrons onto NADP + .
A hydroelectric dam uses the energy of water flowing downhill to make electricity. Water is piled up behind the dam and the energy of this water gradient to converted to electrical energy. The role of water in a hydroelectric dam is the same as the role of ______ in photosynthetic ATP formation and of ______ in mitochondrial ATP formation. A) protons (H+); electrons B) protons (H+); protons (H+) C) electrons; protons (H+) D) sunlight; sugars
protons (H+); protons (H+) (explanation: ATP formation with the help of an ATP synthase is the same in the processes of both photosynthesis and cellular respiration, and this is driven by flow of protons through the ATP synthase from an area of higher concentration to lower concentration. Therefore, protons is the correct answer for both blanks. Protons pile up behind the inner membranes of chloroplasts and mitochondria like water behind a dam and then flow downhill energizing ATP just like water flows downhill making electricity in the hydroelectric dam. Energized electrons only play an indirect role in the process of ATP formation since positively charged H+ are carried along with negatively charged electrons for part of the electron transport chains, which pumps protons from regions of low to high concentration. Sunlight and sugars also only play an indirect role in photosynthetic ATP formation and respiratory ATP formation, respectively. Sunlight energizes the electrons in photosynthesis and the energized electrons in sugars are contributed to the mitochondrial electron transport chain.)
Inputs and Outputs what comes out of glycolysis? ______________ ______________ ______________
pyruvate NADH a little ATP
Which dietary carbohydrate(s) is/are digested most rapidly by humans? A) all starches B) cellulose C) sugars and amylose D) sucrose and amylopectin
sucrose and amylopectin (Explanation: High intake of free sugars and of starches that are rapidly converted to free sugars strongly increases blood sugar levels and promotes fat storage. The starch amylopectin has many branches and allows access to many sugar-cleaving enzymes at once. This permits rapid breakdown of amylopectin to glucose. In contrast, the starch amylose is a single strand of hundreds of glucose molecules without branches. This only allows gradual clipping of sugars from the two ends of amylose. Because humans do not synthesize any enzymes that can clip glucose monomers from cellulose fibers, the glucose in cellulose is inaccessible to humans.)
A carbon atom of a CO2 molecule fixed in the chloroplast of a plant can eventually become part of _________________ on its way through an ecosystem?
sugar, starch, or cellulose in a plant, glycogen in a human, and CO2 released again into the atmosphere
What energy source drives electron transport through the photosynthetic electron transport chain? A. water B. sunlight C. ATP D. sugar E. the ATP synthase turbine
sunlight (explanation: Since electrons are tightly held by oxygen in water molecules, water is not a fuel or a source of energy. Photons of light absorbed by chlorophyll molecules provide energy to excite the electrons and drive them through the electron transport chain. ATP, formed with the energy lost by protons flowing through the ATP synthase turbine, is one of the final energized products. ATP results from, but does not drive, electron transport. Sugar is the final, stable energy-rich product of the entire process of photosynthesis, but it plays no role in electron transport.)
The external energy source for producers is ________ and the final energy-rich product produced in the mitochondria of consumers is ________.
sunlight; ATP
Chloroplasts move protons from ___________________ to build a proton gradient
the stroma to the inner thylakoid space.
Cells use the energy of food molecules to form ATP. Deduce which of the following does NOT represent a state of high energy. A) C-H bonds in food molecules B) H (electrons + H+) in NADH C) the H+ gradient across the mitochondrial membrane D) the water formed at the end of the mitochondrial electron transport chain E) the ATP formed
the water formed at the end of the mitochondrial electron transport chain (explanation: This is not the first time we have seen a question like this. The electrons in both the C-H bonds and in the NADH shuttle are energized and thus represent a state of high energy. A high concentration of any substance on one side of a membrane compared to the other side (such as a high concentration of protons in the intermembrane space of a mitochondrion) represents a state of high energy that has the potential to be used (like water behind a hydroelectric dam). And, as we stated before, ATP is THE readily usable energy currency of the cell. On the other hand, water is not a fuel and has no energy to give, as its electrons are already held tightly by oxygen.)
Which process is NOT fueled by ATP produced in cellular respiration. First exclude the four processes that are fueled by ATP produced in cellular respiration. A) building gradients of substances across the outer cell membrane B) movement of vesicles along cytoskeletal tracks C) transport of protons (H+) from low concentration in the mitochondrial matrix to high concentration in the mitochondrial intermembrane space D) chemical work E) phosphorylation of a motor protein in the cytosol
transport of protons (H+) from low concentration in the mitochondrial matrix to high concentration in the mitochondrial intermembrane space
ALL of the energy is released as HEAT when protons (H+) flow from high to low concentration through the
uncoupling protein in mitochondria.
Which CANNOT provide energy? First exclude the four that do provide energy. A) glucose B) excited electrons C) NADPH D) ATP E)water
water
The light reactions of photosynthesis use _____ and produce _____.
water ... NADPH (NADPH is a reactant in the Calvin cycle.)
The electrons for photosynthetic electron transport are obtained from _________ and the electrons flowing through the mitochondrial electron transport chain are picked up by _________ in cellular respiration. A) oxygen, water B) NADPH; NADH C) sugars; oxygen D) water; oxygen E) water; NAD+
water; oxygen (explanation: In photosynthesis, water is split into its partner atoms H (or rather 2 H+ and 2 electrons) and O. The electrons replace electrons in chlorophyll that are one-by-one energized and propelled into the electron transport chain. When the energized electrons reach the end of the mitochondrial electron transport chain, an oxygen molecule picks up the electrons and adds H+ to form water again. NADPH and NADH shuttle H+ and energized electrons between electron transport and the carbon conversion reactions in either photosynthesis or cellular respiration, respectively. Sugars are a stable form of chemical energy (with C-H bonds) that serves as an intermediary between photosynthesis and cellular respiration. Sugars are the final energy-rich product of photosynthesis that feeds into the process of cellular respiration. Try filling in these participants and steps in the next slide!)
