Midterm 2 Exam 2020 Prof. Alex Pettit PDF

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Variety of midterm 2 questions and answers from Prof. Alex Pettit....

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BIO1140 Introduction to Cell Biology Professor: Dr. Alexandra Pettit Midterm Exam 1 – Section C: Tuesday March 9, 2020 PLEASE DO NOT OPEN THE EXAM UNTIL YOU ARE INSTRUCTED TO DO SO.

MAKE SURE YOU HAVE A COMPLETE EXAM PACKAGE: 1 MCQ QUESTIONNAIRE (7 PAGES) 1 WRITTEN ANSWER QUESTIONNAIRE AND 1 SCANTRON SHEET Cellular phones, unauthorized electronic devices or course notes are not allowed during this exam. Phones and devices must be turned off and put away in your bag. Do not keep them in your possession, such as in your pockets. If caught with such a device or document, the following may occur: You will be asked to leave immediately the exam, academic fraud allegations will be filed which may result in you obtaining a 0 (zero) for the exam. By participating in the exam, you acknowledge that you have ensured that you are complying with the above statement.

General Instructions: 1. This exam is worth 15% of your final mark. 2. You will have 1hour and 15 minutes (75 minutes) to write the exam. 3. Write your name and student number within the spaces provided on all 7 pages. 4. You should only have writing material and this exam on your desk, nothing else. 5. When you have finished, you may return your exam and leave the room. Part A Instructions (24 marks): Multiple Choice. 1. Use pencil. On the Scantron, write down your exam version code (BIO1140C) in the course code field. Also write your student number and name; be sure to fill in the bubbles accordingly. 2. Indicate only one answer for each of the 24 multiple choice questions, directly on the computer scan sheet (Scantron). Do not attempt to change an answer if you use ink. This will be recorded as ‘incorrect’. You will need a new scantron sheet. 3. Please transfer all your answers to the Scantron sheet prior to the end of the exam. You will not be given extra time to do so and the proctors will not do it for you. 4. Follow instructions on the scantron sheet.  

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Part A - Multiple Choice (24 questions, 1 mark each = 24 marks) Select only the single best answer. Please transfer your answers, in pencil, to the Scantron sheet provided – we will not transfer answers 1) For living organisms, which of the following is an important consequence of the first law of thermodynamics? A. The energy content of an organism is constant. B. The organism ultimately must obtain all of the necessary energy for life from its environment. C. The entropy of an organism decreases with time as the organism grows in complexity. D. Organisms grow by converting energy into organic matter. E. Life does not obey the first law of thermodynamics.

2) The metabolic reactions in a healthy living cell exist in a state of chemical equilibrium. A. True B. False

3) According to the induced-fit hypothesis of enzyme catalysis, which of the following is correct? A. The binding of the substrate depends on the shape of the active site. B. Some enzymes change their structure when activators bind to the enzyme. C. A competitive inhibitor can outcompete the substrate for the active site. D. The binding of the substrate changes the shape of the enzyme's active site. E. The active site creates a microenvironment ideal for the reaction.

4) Why is ATP an important molecule in metabolism? A. Its hydrolysis provides an input of free energy for exergonic reactions. B. It provides energy coupling between exergonic and endergonic reactions. C. Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. D. Its terminal phosphate bond has higher energy than the other two. E. It is one of the four building blocks for DNA synthesis.

5) Supposing the formation of acetyl-CoA from acetate and CoA has a G of +29.4 kJ/mol and the hydrolysis of ATP has a G of -30 kJ/mol, would coupling these two reactions be sufficient to allow the formation of acetyl-CoA to proceed? A. Yes B. No C. The question does not provide sufficient information to decide

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6) Which of the following statements best describes the relationship between photosynthesis and respiration? A. Respiration runs the biochemical pathways of photosynthesis in reverse. B. Photosynthesis stores energy in complex organic molecules, whereas respiration releases it. C. Photosynthesis occurs only in plants and respiration occurs only in animals. D. ATP molecules are produced in photosynthesis and used up in respiration. E. Respiration is anabolic and photosynthesis is catabolic

7) Which of the following statements describes the results of this reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy A. C6H12O6 is oxidized and O2 is reduced. B. O2 is oxidized and H2O is reduced. C. CO2 is reduced and O2 is oxidized. D. C6H12O6 is reduced and CO2 is oxidized. E. O2 is reduced and CO2 is oxidized.

8) During glycolysis, when each molecule of glucose is catabolized to two molecules of pyruvate, most of the potential energy contained in glucose is A. transferred to ADP, forming ATP. B. transferred directly to ATP. C. retained in the two pyruvates. D. stored in the NADH produced. E. used to phosphorylate fructose to form fructose 6-phosphate.

9) The ATP made during glycolysis is generated by A. substrate-level phosphorylation. B. electron transport. C. photophosphorylation. D. chemiosmosis. E. oxidation of NADH to NAD+.

10) The ATP made during oxidative phosphorylation is generated by A. substrate-level phosphorylation. B. electron transport. C. photophosphorylation. D. chemiosmosis. E. oxidation of NADH to NAD+.

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11) Carbon dioxide (CO) is released during which of the following stages of cellular respiration? A. glycolysis and the oxidation of pyruvate to acetyl CoA B. oxidation of pyruvate to acetyl CoA and the citric acid cycle C. the citric acid cycle and oxidative phosphorylation D. oxidative phosphorylation and fermentation E. fermentation and glycolysis

12) Which of the following best describes how the citric acid cycle relates to glycolysis, oxidative phosphorylation, and chemiosmosis? A. Citric acid produces NADH and FADH2, which undergo oxidative phosphorylation. This produces ATP by pumping protons through chemiosmosis. The ATP produced is utilized in large amounts in the process of glycolysis. B. Glycolysis produces pyruvate, which directly enters the citric acid cycle. This cycle produces the energy currency that undergoes the electron transport chain to produce water and ATP. C. Glycolysis produces pyruvate, which is converted to acetyl-CoA and enters the citric acid cycle. This cycle produces NADH and FADH2, which donate electrons to the electron transport chain to pump protons and produce ATP through chemiosmosis. Production of ATP using an electron transport chain and chemiosmosis is called oxidative phosphorylation. D. The citric acid produces pyruvate, which converts to glucose to enter glycolysis. This pathway produces NADH and FADH2, which enter oxidative phosphorylation to produce ATP through chemiosmosis.

13) Which kind of metabolic poison would most directly interfere with glycolysis? A. an agent that reacts with oxygen and depletes its concentration in the cell B. an agent that binds to pyruvate and inactivates it C. an agent that closely mimics the structure of glucose but cannot be metabolized D. an agent that reacts with NADH and oxidizes it to NAD+ E. an agent that blocks the passage of electrons along the electron transport chain

14) Phosphofructokinase is an enzyme that catalyzes the conversion of fructose 6phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen, an increase in the amount of ATP in a cell would be expected to A. inhibit the enzyme and thus slow the rates of glycolysis and the citric acid cycle. B. activate the enzyme and thus slow the rates of glycolysis and the citric acid cycle. C. inhibit the enzyme and thus increase the rates of glycolysis and the citric acid cycle. D. activate the enzyme and increase the rates of glycolysis and the citric acid cycle.

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Use the image below to answer questions 15-17. 15) is … A. B. C. D. E.

The type of communication depicted

16) A. B. C. D. E.

The receptor labeled A is a…. GPCR RTK Ligand gated ion channel Intracellular receptor Intracellular ion channel

17) A. B. C. D.

The molecules labeled B are the … Neurotransmitters Second messengers Relay molecule Sodium ions

juxtacrine signalling. autocrine signalling. endocrine signalling. synaptic signalling None of the above

18) Muscle contractions are triggered when a skeletal muscle cell receives acetylcholine secreted from an adjacent neuron. Botulism is an illness caused by Botulinum toxin, produced by the bacterium Clostridium botulinum. The toxin inactivates synaptobrevin, a membrane protein of synaptic vesicles, required for exocytosis. You can expect the frequency of muscle contraction to __________in patients with Botulism relative to unaffected individuals. A. increase B. decrease C. be unaffected

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Use the following figure to answer the questions 19-20. 19) A. B. C. D. E.

The structure labeled A is a(n) signalling molecule. second messenger. activated relay molecule. receptor. phosphorylation cascade.

20) In the diagram, the structure labeled D is a(n) A. first messenger. B. second messenger. C. activated relay molecule. D. receptor. E. phosphorylation cascade.

21) Which of the following is true for the signalling system in an animal cell that lacks the ability to produce GTP? A. It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. B. It would be able to carry out reception and transduction but would not be able to respond to a signal. C. It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. D. It would employ a transduction pathway directly from an external messenger.

22) An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum? A. tyrosine kinases B. serine/threonine kinases C. phosphodiesterase D. phospholipase C E. adenylyl cyclase

23) Which of the following is the best explanation for the fact that most transduction pathways have multiple steps? A. Most of the steps were already in place because they are steps in other pathways. B. Multiple steps in a pathway require the least amount of ATP. C. Multiple steps provide for greater possible amplification of a signal. D. Each individual step can remove excess phosphate groups from the cytoplasm. E. Each step can be activated by several G proteins simultaneously.

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24) Consider the signaling pathway depicted below, which involves two different receptors. Assume that a protein is active only when it is activated by its upstream signaling molecules. Activation and inhibition are indicated by normal and blunt arrows, respectively. Under which of the following conditions is target-gene expression induced?

Signal2

Signal1 GPCR

RTK

Gprotein

Enzyme

Kinase

Kinase

Adaptor

Secondmessenger Kinase

Bindingprotein Transcriptionregulator Geneexpressionand cellularresponse

A. B. C. D. E.

Only in the presence of both signals (1 and 2) In the presence of either or both signals (1 or 2) In the presence of either signal but not both of them Only in the absence of both signals Only in the presence of signal 2 but not signal 1

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