Mastering Biology HW #4
Identify the chloroplast.
A green dots
Drag the numbers on the left to complete the sentence on the right. Numbers may be used once, more than once, or not at all. For every molecule of O2 that is released by photosystem II, _________ H2O molecules are needed, which together pass _________ electrons to the PS II reaction-center complex.
2, 4
The complete oxidation of two molecules of glucose (C6H12O6) in cellular respiration produces about how many molecules of ATP?
60- 64
Which of the following statements is not true of most cellular redox reactions?
A hydrogen atom is transferred to the atom that loses an electron.
How would anaerobic conditions (when no O2O2 is present) affect the rate of electron transport and ATPATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATPATP synthesis in glycolysis or the citric acid cycle.)
Both electron transport and ATPATP synthesis would stop
Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?
Carbon dioxide
In C4 and CAM plants carbon dioxide is fixed in the _____ of mesophyll cells
Cytoplasm
Identify a thylakoid.
D (coin looking objects)
Match each stage of cellular respiration with the cellular location in which it occurs. Labels may be used once, more than once, or not at all.
Glycolysis - Cytosol Acetyl CoA - Mitochondrial matrix Citric acid cycle - Mitochondrial matrix Oxidative phosphorylation - inner mitochondrial membrane
What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?
Ionic -also called electrovalent bond, type of linkage formed from the electrostatic attraction between oppositely charged ions in a chemical compound
Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct.
It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.
A glucose molecule is completely broken down to carbon dioxide and water in glycolysis and the citric acid cycle, but together these two processes yield only a few molecules of ATP. What happened to most of the energy that the cell obtains from the oxidation of glucose?
It is stored in NADH and FADH2
Which of the following describes the process of glycolysis?
It represents the first stage in the chemical oxidation of glucose by a cell.
Match each product of pyruvate metabolism with the condition under which it is produced. Drag each item to the appropriate bin.
Lactate: fermentation in human muscle Ethanol: fermentation in yeast and bacteria Acetyl CoA: aerobic oxidation (In the presence of oxygen, human cells carry out aerobic respiration, which yields acetyl CoA. In the absence of oxygen, human cells can carry out lactic acid fermentation, which yields lactate. Yeasts and many bacteria carry out alcohol fermentation, which takes place under anaerobic conditions, and produces ethanol)
Identify the stroma
E (space between thylakoid and membrane)
Which stage of glucose metabolism produces the most ATP?
Electron transport and chemiosmosis
Which term describes the degree to which an element attracts electrons?
Electronegativity.
Why is it correct to say that the linear electron flow of the light reactions directly captures energy in NADPH but only indirectly captures energy in ATP?
Electrons are directly transferred to NADP+ to form NADPH, but electron flow is used to generate a proton gradient for ATP synthesis. Electrons are not directly transferred to ATP.
Which step of the cellular respiration pathway can take place in the absence of oxygen?
Glycolysis - the first step in all types of cellular respiration is anaerobic and does not require oxygen.
You obtain the pigments called carotenoids in your diet when you eat carrots. Why do carotenoids appear yellow and orange?
They absorb blue/green light and reflect yellow and red wavelengths of light.
What is the biological significance of the light-independent reactions of photosynthesis?
They convert carbon dioxide to sugar.
Which of the following statements correctly describes how ATP is involved in the oxidation of one molecule of glucose in glycolysis?
Two molecules of ATP are used, and four molecules of ATP are produced.
Which of the following statements about the electron transport chain is true?
NADH and FADH2 donate their electrons to the chain.
Which of the following molecules is the primary product of photosystem I?
NADPH
Drag each compound to the appropriate bin. If the compound is not involved in glycolysis, drag it to the "not input or output" bin.
Net Input: ADP, NAD⁺, Glucose Net Output: ATP, NADH and Pyruvate, not input or output: O₂, CO₂, coenzyme A and acetyl CoA
Drag each compound to the appropriate bin. If a compound is not involved in the citric acid cycle, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of the citric acid cycle are included.)
Net Input: Acetyl CoA, NAD⁺, ADP Net Output: Coenzyme A, CO₂, NADH, ATP Not Input or Output: Pyruvate, Glucose, O₂
Can you tell from these absorption spectra whether red light is effective in driving photosynthesis?
One cannot tell from this graph, but because chlorophyll a does absorb red light, we can predict that it would be effective in driving photosynthesis.
Gaseous hydrogen burns in the presence of oxygen to form water:2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed?
hydrogen, polar - water is polar
Which set of reactions uses H2O and produces O2?
light dependent reactions - Light independent creates glucose
Photosynthesis is a redox reaction. H2O is _____ during the light reactions and CO2 is _____ during the Calvin cycle.
oxidized...reduced - Water is broken down during photosynthesis to release oxygen
In C3 plants the conservation of water promotes
photorespiration
The NADPH required for the Calvin cycle is produced by which of the following metabolic reactions?
reactions initiated in photosystem I
In mitochondrial electron transport, what is the direct role of O2?
to function as the final electron acceptor in the electron transport chain
C4 plants differ from C3 and CAM plants in that C4 plants
transfer fixed carbon dioxide to cells in which the Calvin cycle occurs
How many electrons at a time are passed between the pigment molecules in the light-harvesting complexes
0
Approximately what wavelength of light is best absorbed by chlorophyll a, the pigment that participates directly in the light reactions?
435 nm
Which wavelength of light is best absorbed by chlorophyll b?
455 nm
Drag the labels from the left (which represent numbers of carbon atoms) onto the diagram to identify the number of carbon atoms in each intermediate in acetyl CoA formation and the citric acid cycle. Labels may be used more than once.
A) 2 C B) 6 C C) 6 C D) 5 C E) 4 C F) 4 C G) 4 C H) 4 C I) 4 C
Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?
Anion and cation
Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?
Fermentation
NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule. Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2?
Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor
Which molecule is metabolized in a cell to produce energy "currency" in the form of ATP?
Glucose
Which of the following is the correct order of electron flow in the light reactions of photosynthesis?
H2O → P680 chlorophyll a pair → PS II primary electron acceptor → Pq → cytochrome complex → Pc → P700 chlorophyll a pair → PS I primary electron acceptor → Fd → NADPH
Drag each compound to the appropriate bin. If a compound is not involved in oxidative phosphorylation, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of oxidative phosphorylation are listed.)
Net Input: NADH, ADP, O₂Net Output: NAD⁺, ATP, CO₂ and Water Not Input or Output: Pyruvate, Glucose, Acetyl CoA, Coenzyme A and CO₂.
Drag each compound to the appropriate bin. If a compound is not involved in acetyl CoA formation, drag it to the "not input or output" bin. (Note that not all of the inputs and outputs of acetyl CoA formation are included.)
Net Input: NAD⁺, coenzyme A, pyruvate Net Output: NADH, acetyl CoA, CO₂ not input or output: O₂, ADP, glucose and ATP
Photorespiration occurs when rubisco combines RuBP with which of the following molecules?
O2
If the Calvin cycle slows down, what will happen to the rate of O2 production in PS II, and why?
O2 production will slow down because less NADP+ will be regenerated in the Calvin cycle.
Which of the following statements is true of the bonds in a water molecule?
Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. - Oxygen is negatively charged
Which process produces oxygen?
Photosynthesis
Sort the following items according to whether they are reactants or products in the anaerobic reduction of pyruvate during lactic acid fermentation. Drag each item to the appropriate bin.
REACTANTS- pyruvate, NADH PRODUCTS-lactate, NAD+
When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons (H+ ions). If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation? (Assume that gramicidin does not affect the production of NADH and FADH2 during the early stages of cellular respiration.) Sort the labels into the correct bin according to the effect that gramicidin would have on each process.
Remains the same: proton pumping rate, electron transport rate, rate of oxygen uptake Decreases or goes to zero: Rate of ATP synthesis, size of the proton gradient
Which molecule is regenerated in the regeneration phase of the Calvin cycle? Without regeneration of this molecule, the Calvin cycle would stop.
RuBP
Select the correct statement about the Calvin cycle.
The Calvin cycle has three phases: carbon fixation, reduction, and regeneration of RuBP
When a pigment molecule in a light-harvesting complex absorbs a photon of light, what happens to its excited-state electron?
The electron falls back to its ground state, while passing its excited-state energy to an electron in a nearby pigment molecule.
If only chlorophyll a were involved in the light reactions, would blue light (wavelength about 490 nm) be effective in driving photosynthesis?
The graph indicates that chlorophyll a absorbs very little blue light, so we can predict that blue light would not be effective.
How will a healthy individual's ATP production change during an eight-hour fast?
The individual's ATP production will not change significantly.
Which statement about the citric acid cycle is correct?
The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.
Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?
The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions.
What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?
The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars
Suppose that the concentration of CO2 available for the Calvin cycle decreased by 50% (because the stomata closed to conserve water). Which statement correctly describes how O2 production would be affected? (Assume that the light intensity does not change.)
The rate of O2 production would decrease because the rate of ADP and NADP+ production by the Calvin cycle would decrease.
An action spectrum plots the rate of photosynthesis at various wavelengths of visible light, and it shows that blue light with a wavelength of about 490 nm is effective in driving photosynthesis. Based on this information and the absorption spectra shown at left, what role may chlorophyll b and carotenoids play in photosynthesis?
These pigments are able to absorb more wavelengths of light (and thus more energy) than chlorophyll a alone can absorb. As part of light-harvesting complexes in photosystems, they broaden the range of light that can be used in the light reactions.
Carotenoids are found in several foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?
They absorb and dissipate excess light energy that might otherwise react with oxygen to form harmful oxidative molecules.
The light-dependent reactions of photosynthesis use water and produce oxygen.
True
True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.
True
True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.
True
Drag the labels on the left to show the net redox reaction in acetyl CoA formation and the citric acid cycle. Note that two types of electron carriers are involved.
a) CO2 (b) NADH (c) FAD (d)FADH2
For each intermediate compound in the Calvin cycle, identify the number of molecules of that intermediate and the total number of carbon atoms contained in those molecules. As an example, the output G3P is labeled for you: 1 molecule with a total of 3 carbon atoms. Labels may be used once, more than once, or not at all.
a. 3 molecules 3 carbons b. 6 molecules 18 carbons c. 6 molecules 18 carbons d. 5 molecules 15 carbons e. 3 molecules 15 carbons f. 3 molecules 15 carbons
Drag the labels to the appropriate targets to indicate the numbers of molecules of ATP/ADP, NADPH/NADP+, and Pi (inorganic phosphate groups) that are input to or output from the Calvin cycle. Labels can be used once, more than once, or not at all.
a. 6 ATP 6 ADP b. 6 NADPH 6 NADP+ c. 6pid. 2pie. 3 ADP 3 ATP
Drag the labels from the left to their correct locations in the concept map on the right. Not all labels will be used.
a. sunlight b. photosynthesis c. chloroplasts d. sugar e. chlorophyll f. carbon dioxide g. cellular respiration h. mitochondria
