1 Show Which of these enters the citric acid cycle? -G3P -glucose -acetyl CoA -NADH + H+ -pyruvate 2 In the citric acid cycle, ATP molecules are produced by _____. cellular respiration -substrate-level phosphorylation 3 Which of these is NOT a product of the citric acid cycle? ATP 4 In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction. Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct. -More ATP is produced per CO2 released in cyclic processes than in linear processes. -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 Although it is possible to oxidize the two-carbon acetyl group of acetyl CoA to two molecules of CO2, it is much more difficult than adding the acetyl group to a four-carbon acid to form a six-carbon acid (citrate). Citrate can then be oxidized sequentially to release two molecules of CO2. 5 Which molecule is metabolized in a cell to produce energy for performing work? Phosphate -Glucose Glucose is used to produce high-energy ATP in a cell. 6 True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups. True The three phosphate groups in an ATP molecule carry negative charges that strongly repel each other and give ATP a large amount of potential energy. 7 Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell? Glycolysis Fermentation Fermentation is an alternate pathway used when oxygen levels are low. 8 Which step of the cellular respiration pathway can take place in the absence of oxygen? Krebs cycle Glycolysis Glycolysis can take place in the absence of oxygen; its product, pyruvate, enters the cellular respiration pathway or undergoes fermentation depending on the availability of oxygen. 9 Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration? NADH Carbon Dioxide All of the carbon atoms in glucose are incorporated into carbon dioxide: Two molecules are formed as pyruvate is converted to acetyl CoA, and four molecules are formed during the Krebs cycle. 10 Which of the following statements about the electron transport chain is true? The electron transport chain is the first step in cellular respiration. NADH and FADH2 donate their electrons to the chain The electrons lose energy as they move down the chain, and this energy is used to create a proton gradient that drives the synthesis of ATP. 11 Which stage of glucose metabolism produces the most ATP? Krebs cycle Electron transport and chemiosmosis Electron transport and chemiosmosis (oxidative phosphorylation) can yield around 26 molecules of ATP. 12 True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria. True TRUE Glycolysis takes place in the cytoplasm, whereas the Krebs cycle and the electron transport chain, which generate the largest amounts of ATP during cellular respiration, take place in the mitochondria. 13 In mitochondrial electron transport, what is the direct role of O2? -to function as the final electron acceptor in the electron transport chain To function as the final electron acceptor in the electron transport chain The only place that O2 participates in cellular respiration is at the end of the electron transport chain, as the final electron acceptor. Oxygen's high affinity for electrons ensures its success in this role. Its contributions to driving electron transport, forming a proton gradient, and synthesizing ATP are all indirect effects of its role as the terminal electron acceptor. 14 How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.) Neither electron transport nor ATP synthesis would be affected. -Both electron transport and ATP synthesis would stop Oxygen plays an essential role in cellular respiration because it is the final electron acceptor for the entire process. Without O2, mitochondria are unable to oxidize the NADH and FADH2 produced in the first three steps of cellular respiration, and thus cannot make any ATP via oxidative phosphorylation. In addition, without O2 the mitochondria cannot oxidize the NADH and FADH2 back to NAD+ and FAD, which are needed as inputs to the first three stages of cellular respiration. 15 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. -Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. Electrons derived from the oxidation of FADH2 enter the electron transport chain at Complex II, farther down the chain than electrons from NADH (which enter at Complex I). This results in fewer H+ ions being pumped across the membrane for FADH2 compared to NADH, as this diagram shows. Thus, more ATP can be produced per NADH than FADH2. 16 How many NADH are produced by glycolysis? 2 2 Two NADH molecules are produced by glycolysis. 17 In glycolysis, ATP molecules are produced by _____. photosynthesis Substrate-level phosphorylation A phosphate group is transferred from glyceraldehyde phosphate to ADP. 18 Which of these is NOT a product of glycolysis? NADH FADH2 FADH2 is a product of the citric acid cycle. 19 In glycolysis, what starts the process of glucose oxidation? NADPH -ATP Some ATP energy is used to start the process of glucose oxidation. 20 In glycolysis there is a net gain of _____ ATP. 2 -2 It takes 2 ATP to produce 4 ATP. 21 When a compound donates (loses) electrons, that compound becomes _________. Such a compound is often referred to as an electron donor. 22 2. When a compound accepts (gains) electrons, that compound becomes __________. Such a compound is often referred to as an electron acceptor. 23 3. In glycolysis, the carbon-containing compound that functions as the electron donor is ______________. 24 Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called __________. 25 5. ____________ is the compound that functions as the electron acceptor in glycolysis. 26 6. The reduced form of the electron acceptor in glycolysis is ___________. 27 Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions? CO2 only -pyruvate, ATP, NADH ATP is the main product of cellular respiration that contains energy that can be used by other cellular processes. Some ATP is made in glycolysis. In addition, the NADH and pyruvate produced in glycolysis are used in subsequent steps of cellular respiration to make even more ATP. 28 Sort the statements into the appropriate bin depending on whether or not they correctly describe some aspect of substrate-level phosphorylation in glycolysis.
CORRECT: -An enzyme is required in order for the reaction to occur -One of the substrates is a molecule derived from the breakdown of glucose -A bond must be broken between an organic molecule and a phosphate before ATP can form INCORRECT: -The enzymes involved in ATP synthesis must be attached to a membrane to produce ATP. -The phosphate group added to ADP to make ATP comes from free inorganic phosphate ions 29 In muscle cells, fermentation produces _____. carbon dioxide, ethanol, NADH, and ATP lactate and NAD+ These are the products of fermentation as it occurs in muscle cells. 30 In fermentation _____ is reduced and _____ is oxidized. NADH ... lactate -pyruvate......NADH The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+. 31 Part A C B This is a receptor molecule. 32 A signal transduction pathway is initiated when a _____ binds to a receptor. G protein Signal Molecule The binding of a signal molecule to a receptor initiates a signal transduction pathway. 33 Which of these is a signal molecule? A A This is a signal molecule 34 A signal molecule is also known as a(n) _____. key Ligand A ligand is a signal molecule. 35 Which of these is the second of the three stages of cell signaling? gene activation
Transduction Transduction is the second of the three stages of cell signaling. 36 Which of these receptors is NOT a membrane receptor? A E D B C E This receptor is not associated with the plasma membrane. 37 Which of these is a G-protein-linked receptor? E A This is a G-protein-linked receptor. 38 Which of these is a receptor tyrosine kinase? C C This is a receptor tyrosine kinase. 39 Which of these is an ion-channel receptor? D D This receptor does form a channel.
40 The binding of signal molecules to _____ results in the phosphorylation of tyrosines. A C The binding of signal molecules to tyrosine-kinase receptors activates tyrosine-kinase enzymes, which phosphorylate tyrosines. 41 Which of these receptor molecules would allow Na+ to flow into the cell? A D This is an ion-channel receptor. 42 Which of these extracellular signal molecules could diffuse through a plasma membrane and bind to an intracellular receptor? glucose . Estrogen Nonpolar molecules can diffuse through the plasma membrane and bind to intracellular receptors 43 A(n) _____ is an example of a signal molecule that can bind to an intracellular receptor and thereby cause a gene to be turned on or off. carbohydrate Steroid Steroids bind to intracellular receptors, which can then bind to, and regulate, the expression of genes. 44 _____ is a signal molecule that binds to an intracellular receptor D D Steroids are nonpolar and can diffuse through the plasma membrane 45 Thyroid hormones bind to _____ receptors. steroid Intracellular Thyroid hormones are able to pass through the plasma membrane. 46 Which of these acts as a second messenger? D D This is a second messenger. 47 Which of these is responsible for initiating a signal transduction pathway?A B A This is a signal molecule. The attachment of a signal molecule to a plasma membrane receptor initiates a signal transduction pathway. 48 What role does a transcription factor play in a signal transduction pathway? -By binding to a plasma membrane receptor it initiates a cascade. This is the function of a transcription factor. By binding to DNA it triggers the Transcription of a specific gene This is the function of a transcription factor. 49 Which of these is a membrane receptor? A B This is a receptor molecule. 50 A signal transduction pathway is initiated when a _____ binds to a receptor. G protein Signal Molecule The binding of a signal molecule to a receptor initiates a signal trane 51 Which of these acts as a second messenger? protein
kinase Cyclic AMP Cyclic AMP can act as second messengers. 52 Calcium ions that act as second messengers are stored in _____. endoplasmic reticula Endoplasmic Reticula The ER stores calcium ions. 53 _____ catalyzes the production of _____, which then opens an ion channel that releases _____ into the cell's cytoplasm. Adenylyl cyclase ... IP3 .... Ca2+ Phospholipase C ... IP3 .... Ca2+ Phospholipase C cleaves IP3 from a membrane protein, and IP3 then binds to a calcium channel on the ER. 54 A protein kinase activating many other protein kinases is an example of _____. deactivation Amplification By activating many other molecules the initial signal is amplified. 55 The cleavage of glycogen by glycogen phosphorylase releases _____. glucose-1-phosphate Glucose-1 phosphate Glycogen is a polysaccharide composed of glucose monomers. 56 Epinephrine acts as a signal molecule that attaches to _____ proteins. ion-channel receptor G-protein-linked receptor Epinephrine acts via G-protein-linked receptors. 57 Which of these is activated by calcium ions? G protein Calmodulin Calmodulin is a calcium-binding protein. 58 Which of these is NOT correct? Ion channels are found on both the plasma membrane and the endoplasmic reticulum. Cyclic AMP binds to calmodulin Calcium binds to calmodulin.
59 A toxin that inhibits the production of GTP would interfere with the function of a signal transduction pathway that is initiated by the binding of a signal molecule to _____ receptors. intracellular G-Protein Linked GTP activates G proteins. 60 Orange dye moves independently of purple dye? 61 Concentration gradients exist that drive diffusion both dyes Only before equilibrium is reached 62 There is a net movement of orange dye from side A to B Only before equilibrium is reached 63 Purple dye moves only from side B to side A 64 There is no movement of purple dye 65 Some solutes are able to pass directly through the lipid bilayer of a plasma membrane, whereas other solutes require a transport protein or other mechanism to cross between the inside and the outside of a cell. The fact that the plasma membrane is permeable to some solutes but not others is what is referred
to as selective permeability. lipids Lipids, Oxygen, Water, Carbon Dioxide Some solutes pass readily through the lipid bilayer of a cell membrane, whereas others pass through much more slowly, or not at all.
66 The majority of solutes that diffuse across the plasma membrane cannot move directly through the lipid bilayer. The passive movement of such solutes (down their concentration gradients without the input of cellular energy) requires the presence of specific transport proteins, either channels or carrier proteins. Diffusion through a transport protein in
the plasma membrane is called facilitated diffusion.
ONLY CHANNELS
ONLY CARRIERS
BOTH CHANNELS AND CARRIERS
67 Because ions carry a charge (positive or negative), their transport across a membrane is governed not only by concentration gradients across the membrane but also by differences in charge across the membrane (also referred to as membrane potential). Together, the concentration (chemical) gradient and the charge
difference (electrical gradient) across the plasma membrane make up the electrochemical gradient. Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply. 1. The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane.
The concentration gradient of K+ ions across the membrane (higher K+ concentration inside) facilitates the diffusion of K+ out of the cell. However, the electrical gradient across the membrane (excess positive charge outside) impedes the diffusion of K+ out of the cell. 68 Which of the following statements is TRUE with regard to this animation? Potassium ions are transported down their concentration
gradient. Both sodium and potassium ions are transported against their concentration gradients Both ions are transported from where their concentration is low to where their concentration is high, and the cell expends energy in the form of ATP to do it. 69 Sort the phrases into the appropriate bins depending on whether they describe exocytosis, endocytosis, or both.
EXOCYTOSIS
ENDOCYTOSIS
BOTH
In exocytosis, substances are transported to the plasma membrane in vesicles derived from the endomembrane system. These vesicles fuse with the plasma membrane, releasing the enclosed substances outside the cell. In endocytosis, substances are taken into the cell by folding in of the plasma membrane and pinching off of the membrane to form a vesicle. Notice that in both exocytosis and endocytosis, the transported substances never actually cross the plasma membrane as they leave or enter the cell. 70 Endocytosis moves materials _____ a cell via _____. into ... membranous vesicles Into...... membranous vesicles The prefix "endo-" means "inward." 71 You can recognize the process of pinocytosis when _____. the cell is engulfing a large particle The cell is engulfing extracellular fluid Pinocytosis is "cell drinking." 72 A white blood cell engulfing a bacterium is an example of _____. exocytosis Phagocytosis Phagocytosis occurs when a cell engulfs a large particle. 73 What is the function of Structure E? detection of environmental change Stabilization of the phospholipids Cholesterol helps to stabilize the structure of the plasma membrane. 74 Identify Structure D. protein Phospholipid bilayer of membrane Phospholipids can be recognized by the presence of a head and two tails. 75 Identify Structure A. protein Glycoprotein Structure A is composed of both a carbohydrate and a protein. 76 Structure A in the figure is a(n) _____. receptor molecule Transport Protein The protein is allowing solute molecules to enter the cell 77 Which of these cannot rapidly pass directly through the phospholipids of the plasma membrane? A only B,C, and D Ions, such as hydrogen ions, and hydrophilic molecules, such as water and glucose, cannot rapidly pass directly through the phospholipids of a plasma membrane. To move rapidly through the membrane, they must pass through membrane transport proteins. 78 Which of the following factors does not affect membrane permeability? Temperature The polarity of membrane phospholipids Phospholipids contain both a polar head and a nonpolar hydrocarbon tail, both of which are necessary for their ability to form membrane bilayers. 79 How can a lipid be distinguished from a sugar? Lipids are mostly saturated. Lipids are mostly nonpolar Lipids are nonpolar molecules, whereas sugars are polar. 80 True or false? Osmosis is a type of diffusion. True True Osmosis is the diffusion of water across a selectively permeable membrane. 81 What property of dishwashing liquid (detergent) makes it useful to wash grease from pans? Permeability Amphipathic Nature Detergents form micelles around the grease, which are then washed away because the polar head groups facing outward on the micelle are water-soluble. 82 Which of the following particles could diffuse easily through a cell membrane? Hydrogen ion (H+) Oxygen (O2) Small nonpolar molecules such as oxygen can diffuse across cell membranes. 83 True or false? The water-soluble portion of a phospholipid is the polar head, which generally
consists of a glycerol molecule linked to a phosphate group. True True The hydrophilic, or water-loving, portion of a phospholipid is the polar head, whereas the hydrophobic portion is the nonpolar tail. 84 If a red blood cell is placed in a salt solution and bursts, what is the tonicity of the solution relative to the interior of the cell? Hypotonic Hypotonic The salt concentration in the solution is lower than it is in the cell, so water enters the cell, causing it to burst. 85 What name is given to the process by which water crosses a selectively permeable membrane? pinocytosis Osmosis Osmosis is the passive transport of water. 86 This cell is in a(n) _____ solution. hypertonic Hypertonic There is a greater concentration of solute outside the cell. 87 You know that this cell is in a(n) _____ solution because the cell _____. isotonic ... neither lost nor gained water Hypotonic.......swelled A cell will gain water when placed in a hypotonic solution. 88 You know that this cell is in a(n) _____ solution because it _____. hypertonic solution ... lost water Hypertonic solution..... lost water A cell will lose water when placed in a hypertonic solution 89 A human cell placed into a hypertonic solution is likely to burst as a result of osmosis. 90 When a person is dehydrated, his or her IV fluids -are not necessary, since a dehydrated person would not require IV fluids. should be isotonic, because either a hypertonic or hypotonic IV would damage red blood cells. 91 If you are going to bake potatoes, and your potatoes are soft and dehydrated, they can be soaked in __________ to make them more firm before baking. a
hypertonic solution such as distilled water A hypotonic solution such as tap water 92 A human cell placed in a hypotonic environment would lose water through osmosis. take up water through osmosis 93 A cell that neither gains nor loses water while sitting in a solution is probably sitting in a hypotonic environment. 94 Paramecium is a genus of protists that lives in water. It has organelles called contractile vacuoles that continually eliminate the excess water gained through osmosis. Knowing that Paramecia gain water through osmosis, we can deduce that they normally live in ice and very cold environments. freshwater lakes and ponds 95 Many bacteria and fungi have a difficult time surviving on our food if the food is very salty. The best explanation for this is -that the salt in the food creates a hypertonic environment for the bacteria and fungi. that the salt in the food creates a hypertonic environment for the bacteria and fungi 96 If a single layer of phospholipids coats the water in a beaker (NOT A BILAYER), which parts of the molecules will face up into the air? -the hydrocarbon tails 97 The movement of tagged proteins in hybrid cells formed form the fusion of a mice and human plasma membranes best illustrates 1.support for the fluid-mosaic model Support for the fluid-mosaic model 98 Glycoproteins and glycolipids are important for cell-cell recognition 99 Which of the following is an organelle found in a prokaryotic cell? none, prokaryotes do not have organelles. None, prokaryotes do not have organells 100 Autotrophs use which of the following to power cellular work ATP 101 Which of the following is NOT a basic component of cell theory? Viruses are the smallest type of cell. Viruses are the smallest type of cell 102 Which of the following can be found in a bacterial chromosome? DNA 103 The fluidity of membranes in a plant in cold weather may be maintained by increasing the -number of phospholipids with unsaturated hydrocarbon tails. number of phospholipids with unsaturated hydrocarbon tails 104 Facilitated diffusion of ions across a cellular membrane requires _________; and the ions move ___________. -channel proteins; down their electrochemical gradient Channel proteins; down their electrochemical gradient 105 Which of the following is NOT TRUE about osmosis? -It is a passive process in cells without cell walls, but transport across the cell wall requires energy. It is a passive process in cells without cell walls, but transport across the cell wall requires energy 106 Why does the oxidation of organic compounds by molecular oxygen to produce CO2 and water release free energy? -The covalent bonds in organic molecules and molecular oxygen have more kinetic energy than the covalent bonds in water and carbon dioxide. -Electrons are being moved from atoms that have a lower affinity for electrons (such as C) to atoms with a higher affinity for electrons (such as O). 107 The ATP made during glycolysis is generated by -the action of a kinase enzyme. The action of a kinase enzyme 108 Which of the following is the most correct interpretation of the figure? -ATP is a molecule that acts as an intermediary to store energy for cellular work. -ATP is a molecule that acts as an intermediary to store energy for cellular work 109 The primary role of oxygen in cellular respiration is to -act as an acceptor for electrons and hydrogen, forming water. Act as an acceptor for electrons and hydrogen, forming water 110 A number of systems for pumping ions across membranes are powered by ATP. Such ATP-powered pumps are often called ATPases although they don't often hydrolyze ATP unless they are simultaneously transporting ions. Because small increases in calcium ions in the cytosol can trigger a number of different intracellular reactions, cells keep the cytosolic calcium concentration quite low under normal conditions, using ATP-powered calcium pumps. For example, muscle cells transport calcium from the cytosol into the membranous system called the sarcoplasmic reticulum (SR). If a resting muscle cell's cytosol has a free calcium ion concentration of 10-7 while the concentration in the SR is 10-2, then how is the ATPase acting? -ATPase activity must be powering an inflow of calcium from the outside of the cell into the SR. ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient. 111 The electrons carried by NADH and FADH2 can be -transported into the
matrix of the mitochondria. moved between proteins in the inner membrane of the mitochondria 112 What is the importance of fermentation to cellular metabolism? It reduces NADH to NAD+ in the absence of O2. It oxidizes NADH to NAD+ in the absence of O2. 113 Brown fat is special type of fat cell found in human babies and hibernating animals which helps these organisms maintain a high body temperature in hostile environments. Brown fat cells contain mitochondria that express an uncoupling protein located in the inner mitochondrial membrane, thermogenin, that serves as a passive transporter for protons. Brown fat cells can generate ATP and also generate a substantial amount of body heat. What mechanism best explains the role of uncoupling proteins in generating body heat? -Oxidative phosphorylation produces excess heat due to the passive transport of protons. The potential energy of the proton gradient is converted to heat as the protons move down the concentration gradient into the matrix. 114 Animals inhale air containing oxygen and exhale air with
less oxygen and more carbon dioxide. After inhalation, the oxygen missing from the air will mostly be found in organic molecules. 115 In the following redox reaction, _______ is oxidized and _______ is reduced. BPG; NADH + H+ G3P; NAD+ None of the above; the equation does not show a redox reaction. Which of the following statements correctly describes some aspect of exocytosis or endocytosis?The correct answer is that a- Endocytosis and exocytosis involve active transport. Both endocytosis and exocytosis require the use of ATP for the cell to enclose the particles being brought in, or to move the vesicle out of the cell, this makes both of these processes active transport.
What are the types of exocytosis?The three main types of exocytosis are phagocytosis, pinocytosis and receptor-mediated endocytosis.
Does exocytosis move from low to high?movement of substances across a plasma membrane that requires energy because the substance is moving against the concentration gradient, from a lower to higher concentration.
What is the definition of exocytosis quizlet?Exocytosis. a process in which material inside a cell is packaged into vesicles and excreted into the extracellular medium.
|