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Chapter 7 HW
HW answers ch 7
| Question | Answer |
|---|---|
| In terms of the source of their carbon, plants are _________ , and animals are ___________ . | Autotrophs, heterotroph |
| Which statement accurately lists the types of molecules in food that can be used by cells as energy sources? | Many molecules in food can be used as energy sources, including proteins, carbohydrates, and fats. |
| Which of the following best describes redox reactions? | Redox reactions involve the loss and gain of electrons. |
| When NAD+ is reduced it becomes ______. | NADH |
| During the breakdown of glucose, why is it beneficial to release energy a little at a time rather than all at once? | When energy is released a little at a time, cells can recover more energy in a useful form |
| An example of a heterotroph would be which of the following? | an animal |
| ________ is the molecule that powers most of the cell's activities that require energy. | ATP |
| Which of the following molecules in food can be used as energy sources by living organisms? | fats proteins carbohydrates |
| The two reactions involved in a redox reaction are _______ and _______ | oxidation, reduction |
| Which of the following is the reduced form of nicotinamide adenine dinucleotide? | NADH |
| The transfer of a high energy phosphate group from a phosphorylated organic molecule to ADP is referred to as ______. | substrate-level phosphorylation |
| How do cells oxidize their glucose? | A little at a time, so that more of the useful energy can be used to produce ATP |
| Glycolysis results in a net gain of _______ ATP per glucose molecule | two |
| What molecule is considered to be the energy currency of the cell and is used to do work? | ATP |
| Select molecules that are produced during the second half (last 5 steps) of glycolysis | ATP, pyruvate |
| In the presence of oxygen, pyruvate can enter the citric acid cycle but must be converted to ___________ - ___________ first. | acetyl-CoA |
| Which of these statements correctly indicate the location of pyruvate oxidation? | In prokaryotic cells, oxidation of pyruvate occurs in the cytoplasm. In eukaryotic cells, oxidation of pyruvate occurs in the mitochondria. |
| During substrate-level phosphorylation, ATP is made by ______ | transferring a phosphate group from a phosphate-bearing intermediate directly to ADP |
| What molecule enters the citric acid cycle and combines with oxaloacetate to form citric acid? | Acetyl-CoA |
| During the reactions of glycolysis, one molecule of glucose is converted into how many molecules of pyruvate? | Two |
| The first step of the citric acid cycle involves which of the following? | The attachment of an acetyl group to oxaloacetate |
| What happens during the first half of glycolysis? | Two ATPs are used to convert a glucose molecule to 2 G3P molecules. |
| During fermentation, most of the pyruvate produced during glycolysis is used to convert NADH to ___________ | NAD+ |
| Select all of the following that are produced by one round of the Krebs cycle. | 3 molecules of NADH 2 molecules of CO2 |
| Eukaryotic cell ----------- Bacterial cell ---------- | Mitochondria Cytoplasm |
| ___________- CoA enters the Krebs cycle and combines with oxaloacetate to form the 6-carbon molecule ___________ acid | Acetyl citric |
| In the process of aerobic respiration, what molecule is entirely consumed? | Glucose |
| The final step of the Krebs cycle is the regeneration of oxaloacetate, which is produced when NAD+ is reduced to _______ | NADH |
| During aerobic respiration, NADH delivers electrons to ______, and then ______ captures electrons at the end and joins with hydrogen to form water. | the electron transport chain; oxygen |
| Select all of the following that are true statements describing one round of the Krebs cycle. | One molecule of ATP is produced. Four pairs of electrons are removed from four of the intermediates in the cycle. A 2-carbon group from acetyl-CoA enters the cycle |
| Order the complexes in the electron transport chain from first (electrons enter) to last (electrons exit). Start at the top. | NADH dehydrogenase the bc1 complex the cytochrome oxidase complex |
| Select the products yielded by the passage of glucose through glycolysis and the citric acid cycle. | ATP CO2 NADH |
| During each step of the electron transport system, electrons move to a more electronegative carrier, and thus move ______. | down an energy gradient |
| The flow of highly energetic electrons through the electron transport chain changes the ________ of the pump proteins, which causes them to transport protons across the membrane. | Shape |
| The mitochondrial matrix has what charge compared with the intermembrane space? | negative |
| The F0 subportion of ATP synthase contains the membrane-bound complex, and the F1 subportion consists of which of the following? | Stalk and catalytic head |
| Prior to being transferred to oxygen, the last site of electrons in the electron transport chain is which of the following? | The cytochrome oxidase complex |
| In the process of aerobic respiration, what molecule is entirely consumed? | glucose |
| NADH------ FADH2------ | 2.5 1.5 |
| The electrons donated to the electron transport chain by NADH activate ______ proton pumps, while those donated by FADH2 activate ______ proton pumps. | three two |
| The calculation of the P/O ratio depends on the number of binding sites for ATP on ATP synthase and the number of which of the following? | protons required for rotation |
| Which statements accurately compare the intermembrane space and the matrix of a mitochondrion? | The matrix is negative compared to the intermembrane space. There is a higher concentrations of protons in the intermembrane space compared to the matrix. |
| How do ADP and ATP interact with the enzyme phosphofructokinase? | High levels of ATP inhibit phosphofructokinase, while high levels of ADP activate it. |
| Which of the following parts of ATP synthase is composed of the stalk and a knob? | F1 |
| Choose all true statements about anaerobic respiration | Less ATP is made in anaerobic respiration compared to aerobic (cellular) respiration. The final electron acceptor in anaerobic respiration is an inorganic molecule other than oxygen. |
| A cell oxidizes an organic molecule producing 3 NADH molecules and 3 FADH2 molecules. How many ATPs (total) can be synthesized in the ETC from these molecules? | 12 |
| The P/O ratio takes into account the fact that, in the electron transport chain, there are _________ protons pumped across the membrane per NADH and ________ protons pumped across the membrane per FADH2 | 10 6 |
| What do methanogens use as their electron acceptor for anaerobic respiration? | CO2 |
| ATP is an allosteric inhibitor of the enzyme phosphofructokinase. As a result of this feedback mechanism, when levels of ATP are high, what process is directly inhibited? | glycolysis |
| Select the molecules that many prokaryotes are able to use as final electron acceptors during anaerobic respiration. | CO2 Nitrate Sulfur |
| Early sulfate reducers set the stage for the evolution of ______, the first form of which harvested hydrogens from H2S. | photosynthesis |
| Select the carrier molecules that move electrons from complex to complex in the electron transport chain. | Ubiquinone Cytochrome c |
| The two electrons in Blank______ can be used to synthesize 2.5 ATPs in the ETC. | NADH |
| In the absence of oxygen, electrons generated by glycolysis can be donated to organic molecules to recycle NAD+ in a process called | fermentation |
| Where do methanogens get the hydrogens involved in reducing CO2 to CH4 in anaerobic respiration? | From organic molecules produced by other organisms |
| The Blank______ containing group is removed from an amino acid in a process called deamination. | nitrogen |
| The catabolism of fatty acids produces which of the following that can be combined with coenzyme A and enter the Krebs cycle? | acetyl groups |
| In a type of anaerobic respiration called sulfate respiration, prokaryotes derive energy by reducing inorganic sulfates to which of the following compounds? | H2S |
| Select the molecules that are key intermediates in food oxidation pathways, intermediates that allow the interconversion of different molecules. | Acetyl-CoA Pyruvate |
| When ATP levels are high, and the oxidative pathway is inhibited, acetyl Co-A can be channeled into the synthesis of which of the following? | Fatty acids |
| The purpose of fermentation is to recycle which of the following? | NAD+ |
| According to our current understanding, how did cellular respiration evolve? | The different steps in cellular respiration evolved over time. |
| After proteins are broken down into amino acids, the removal of the nitrogen-containing side group is called which of the following? | Deamination |
| Organic molecules that are abiotically produced are made by ______. | inorganic processes |
| In the process known as β oxidation, acetyl groups are removed from the end of which molecules to be combined with coenzyme A to produce acetyl-CoA? | Fatty acid |
| _______ is the step in cellular respiration that does not appear to have changed for more than 2 billion years. | Glycolysis |
| Oxidation pathways of food molecules are interrelated. Which of these is an intermediate that links the breakdown of food molecules from different starting points? | Acetyl Co-A |
| Almost all molecules that are catabolized for energy are converted into which of the following? | Acetyl-CoA |
| When it first appeared, anoxygenic photosynthesis most likely used what molecule as a source for hydrogen atoms? | H2S |
| Cellular respiration is a continuous series of steps that most likely ______. | evolved over time |
| The most primitive forms of life probably obtained chemical energy by degrading ______ molecules that were abiotically produced. | organic |
| The substitution of _______ for H2S in photosynthesis was an important event in the history of metabolism, as it allowed the generation of molecular oxygen. | H2O |
| The second major event in the evolution of metabolism was most likely which of the following? | Glycolysis |
| The ability of organisms to synthesize proteins and nucleic acids was dependent on the evolution of ________ fixation. | nitrogen |
| Aerobic respiration employs the same type of proton pumps as which of the following? | photosynthesis |
| Anoxygenic ________ evolved in the absence of oxygen and allowed some organisms to use light energy to pump protons. | photosynthesis |
| Which of the following is the source of hydrogen in oxygenic photosynthesis? | H2O |
| The evolution of nitrogen fixation was critical for the ability of organisms to synthesize which of the following? | Nucleic acids Proteins |
| Based on current evidence, which organisms were most likely the first to evolve the ability to carry out photosynthesis without H2S? | purple nonsulfur bacteria |
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