BIOL150_Fall19_Exam_2_Key

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1 Exam 2 – Fall 2019 Name ____________Key____________ Biology 150 – General Biology I 150 Points Total Use your scantron sheet for questions #1-50. Multiple Choice – 2 points each 1) Stored energy is ______ energy. A) potential B) kinetic C) created D) unusable E) conserved 2) Which term most precisely describes the cellular process of breaking down large molecules into smaller ones? A) dehydration B) anabolism C) catalysis D) metabolism E) catabolism 3) Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's A) entropy. B) heat content. C) endothermic level. D) free-energy content. E) activation energy. 4) Which component of the following reaction is the enzyme? lactose + lactase + water → lactase + glucose + fructose A) fructose B) lactase C) water D) lactose E) glucose 5) Why is ATP an important molecule in metabolism? A) It provides energy coupling between exergonic and endergonic reactions. B) Its terminal phosphate bond has higher energy than the other two. C) Its hydrolysis provides an input of free energy for exergonic reactions. D) Its terminal phosphate group contains a strong covalent bond that, when hydrolyzed, releases free energy. E) It is one of the four building blocks for DNA synthesis.

2 6) Usually, enzymes are ______. A) monosaccharides B) fats C) steroids D) proteins E) phospholipids 7) T he reaction A → B + C + heat is ______. A) anabolic B) exchange C) exergonic D) dehydration synthesis E) endergonic 8) Which of the following statements most accurately describes a competitive inhibitor? A) A competitive inhibitor has a structure that is so similar to the substrate that it can bind to the enzyme in the same way as the substrate. B) The structure of a competitive inhibitor does not resemble the substrate and does not compete for the active site. C) Most competitive inhibitors are toxic substances that destroy enzymes. D) Competitive inhibitors bind at the enzyme's active site, where the enzyme converts them into the reaction product(s). E) None of the above 9) When ATP releases it energy it becomes ________ . A) ADP B) Heat C) AMP D) AMP + P i E) ADP + P i 10) During redox reactions, ______. A) the loss of electrons from one substance is called reduction B) electrons are lost from one substance and added to another substance C) protons from one molecule replace the electrons lost from another molecule D) a substance that gains electrons is said to be oxidized E) none of the above 11) When a glucose molecule loses a hydrogen atom (proton and an electron) as the result of an oxidation-reduction reaction, the glucose molecule becomes A) hydrogenated. B) an oxidizing agent. C) reduced. D) dehydrogenated. E) oxidized.

3 12) The ATP made during the citric acid cycle is generated by A) chemiosmosis. B) electron transport. C) photophosphorylation. D) oxidation of NADH to NAD + . E) substrate-level phosphorylation. 13) Animals breathe in air containing oxygen and breathe out air with less oxygen and more carbon dioxide. The carbon dioxide comes from A) the citric acid cycle. B) glycolysis. C) water. D) hydrocarbons and the air. E) All of the above 14) Glycolysis is a(n) ______________ metabolic pathway in which glucose C 6 H 12 O 6 is _____________ to produce two molecules of ______________ . A) catabolic; oxidized; CO 2 B) anabolic; oxidized; pyruvate C) catabolic; reduced; pyruvate D) catabolic; oxidized; pyruvate E) catabolic; reduced; CO 2 15) Which stage of cellular respiration requires oxygen? A) Citric acid cycle B) Electron transport chain C) Glycolysis D) Light Reactions E) Calvin cycle 16) During aerobic respiration, electrons travel downhill in which sequence? A) glucose → ATP → electron transport chain → NADH B) food → glycolysis → citric acid cycle → NADH → ATP C) food → citric acid cycle → ATP → NAD+ D) glucose → pyruvate → ATP → oxygen E) food → NADH → electron transport chain → oxygen 17) In mitochondrial electron transport, what is the direct role of O 2 ? A) to provide the driving force for the synthesis of ATP from ADP and P i B) to provide the driving force for the production of a proton gradient C) to oxidize NADH and FADH 2 from glycolysis, acetyl CoA formation, and the citric acid cycle D) to function as the final electron acceptor in the electron transport chain E) to reduce NADH and FADH 2 18 Which of these equations describes anaerobic fermentation in humans? A) energy + carbo n dioxide + water → glucose + oxygen + water B) glucose → ethyl alcohol + carbon dioxide + energy C) glucose + lactose → galactose + water D) glucose + oxygen → carbon dioxide + water + energy E) glucose → lactic acid + energy

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4 19) In glycolysis, glucose (a six-carbon molecule) is broken down to form two molecules of pyruvate. Then, during acetyl CoA formation, pyruvate is converted to acetyl CoA through a series of reactions. Which statement is true about the number of carbon atoms in the compounds involved in acetyl CoA formation? A) Both pyruvate and acetyl CoA are two-carbon molecules. B) Pyruvate is a six-carbon molecule, while acetyl CoA is a five-carbon molecule. One molecule of CO 2 is released. C) Both pyruvate and acetyl CoA are six-carbon molecules. D) Pyruvate is a three-carbon molecule, while acetyl CoA is a two-carbon molecule. One molecule of CO 2 is released. E) Both pyruvate and acetyl CoA are three-carbon molecules. 20) During strenuous exercise, anaerobic conditions can result if the cardiovascular system cannot supply oxygen fast enough to meet the demands of muscle cells. Assume that a muscle cell’s demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions. What would happen to the cell’s rate of glucose utilization? A) Glucose utilization would increase a lot. B) Glucose utilization would increase a little. C) Glucose utilization would remain the same. D) Glucose utilization would decrease a little. E) Glucose utilization would decrease a lot. 21) The most important role of pigments in photosynthesis is to _____. A) screen out harmful ultraviolet rays B) store energy in glucose molecules C) release energy from glucose molecules D) store energy in ATP E) capture light energy 22) Plant cells ______. A) do not use cellular respiration B) have chloroplasts and mitochondria C) do not need chloroplasts because their mitochondria meet their energy needs D) do not need mitochondria because their chloroplasts meet their energy needs E) use carbon dioxide but do not use oxygen 23) Which of these absorbs sunlight? A) Photons B) Wavelengths C) Pigments D) CO 2 E) Mitochondria 24) Where do the enzymatic reactions of the Calvin cycle take place? A) thylakoid membranes B) stroma of the chloroplast C) electron transport chain D) outer membrane of the chloroplast E) thylakoid space

5 25) Which of the following sequences correctly represents the flow of electrons during photosynthesis? A) NADPH → electron transport chain → O 2 B) NADPH → chlorophyll → Calvin cycle C) H 2 O → photosystem I → photosystem II D) NADPH → O 2 → CO 2 E) H 2 O → NADPH → Calvin cycle 26) Which of the following does not occur during the Calvin cycle? A) release of oxygen B) carbon fixation C) oxidation of NADPH D) consumption of ATP E) regeneration of the CO 2 acceptor 27) 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? A) Light supplies the electrons that are needed to reduce NADP + to NADPH. B) Light provides the atoms that are needed to convert ADP to ATP. C) Light energy is used to fix CO 2 into sugar. D) Light supplies the energy to remove electrons from water and to transport those electrons to NADP + . E) Light supplies the electrons that are needed to reduce CO 2 to make sugar. 28) The light reactions of photosynthesis take place ______. A) on the cristae B) in the stroma C) in the outer membrane D) in the thylakoid membrane E) in the cytosol 29) 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) G3P B) CO 2 C) ATP D) RuBP E) NADPH 30) The Calvin cycle is dependent on the light reactions for ATP and NADPH that are required to power the conversion of CO 2 to G3P. Which of these compounds, if any, do the light reactions require from the Calvin cycle? A) RuBP B) G3P C) CO 2 D) NADP+ E) None

6 31) How do the daughter cells at the end of mitosis and cytokinesis compare with their parent cell when it was in G 1 of the cell cycle? A) The daughter cells have half the amount of cytoplasm and half the amount of DNA. B) The daughter cells have the same number of chromosomes and the same amount of DNA. C) The daughter cells have the same number of chromosomes and twice the amount of DNA. D) The daughter cells have half the number of chromosomes and half the amount of DNA. E) The daughter cells have the same number of chromosomes and half the amount of DNA. 32) The chromosomes of eukaryotic cells are found in the ______. A) nucleus B) Golgi apparatus C) centriole D) basal body E) nucleolus 33) The correct sequence of stages of mitosis is ______. A) prophase, metaphase, anaphase, telophase B) interphase, prophase, metaphase, anaphase, telophase C) anaphase, interphase, prophase, metaphase, telophase D) prophase, metaphase, anaphase, telophase, cytokinesis E) telophase, prophase, interphase, anaphase, metaphase 34) Sister chromatids _____. A) are separated during mitosis B) are created when DNA is replicated C) have matching copies of the chromosome's DNA D) are attached at the centromere prior to division E) all of the above 35) Sister chromatids are joined at the ______. A) centrosome B) chromatin C) centriole D) centromere E) spindle 36) During metaphase of mitosis ______. A) the nuclear envelope breaks up B) centromeres divide C) tetrads form D) chromosomes line up on the midline of the cell E) cytokinesis occurs 37) Which term describes centromeres uncoupling, sister chromatids separating, and the two new chromosomes moving to opposite poles of the cell? A) telophase B) anaphase C) prophase D) metaphase E) prometaphase

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7 38) A haploid cell is a cell A) containing only one copy of each chromosome. B) in which the genes are arranged haphazardly. C) that has resulted from the process of mitosis. D) with twice the number of chromosomes of a diploid cell. E) None of the above 39) Why do chromosomes coil and condense during mitosis? A) to allow the sister chromatids to remain attached B) to allow the chromosomes to move without becoming entangled and breaking C) to provide for the structure of the centromere D) to increase their potential energy E) to allow the chromosomes to fit within the nuclear envelope 40) Which of the following is a protein maintained at constant levels throughout the cell cycle that requires cyclin to become catalytically active? A) protein kinase B) PDGF C) MPF D) cyclin E) Cdk 41) Which of the following results in daughter cells that contain half the number of chromosomes (1N)? A) metaphase B) mitosis C) meiosis D) cytokinesis E) interphase 42) ______ represent sites of crossing over. A) Centromeres B) Chiasmata C) Centrosomes D) Tetrads E) Kinetochores 43) What is a karyotype? A) The set of unique physical characteristics that define an individual B) A display of every pair of homologous chromosomes within a cell, organized according to size and shape C) The collection of all the mutations present within the genome of an individual D) A system of classifying cell nuclei E) The combination of chromosomes found in a gamete

8 44) Homologous chromosomes move toward opposite poles of a dividing cell during A) fertilization. B) meiosis II. C) meiosis I. D) mitosis. E) binary fission. 45) Independent assortment of chromosomes occurs. A) The statement is true for mitosis only. B) The statement is true for meiosis II only. C) The statement is true for mitosis and meiosis II. D) The statement is true for meiosis I only. E) The statement is true for mitosis and meiosis I. 46) Which of the following occurs in meiosis but not in mitosis? A) Chromosome replication B) Production of daughter cells C) Condensation of chromatin D) Synapsis of chromosomes E) Alignment of chromosomes at the equator 47) Anaphase II is essentially the same as mitotic anaphase except that in anaphase II ______ and in mitotic anaphase ______. A) the cells are haploid and sister chromatids separate . . . the cells are diploid and sister chromatids separate B) crossing over occurs . . . crossing over does not occur C) chromosomes line up double file on the midline of the cell . . . chromosomes line up single file on the midline of the cell D) the cells are diploid . . . the cells are haploid E) tetrads do not form . . . tetrads form 48) After telophase I of meiosis, the chromosomal makeup of each daughter cell is A) diploid, and the chromosomes are each composed of a single chromatid. B) haploid, and the chromosomes are each composed of two chromatids. C) haploid, and the chromosomes are each composed of a single chromatid. D) diploid, and the chromosomes are each composed of two chromatids. E) tetraploid, and the chromosomes are each composed of two chromatids. 49) How are sister chromatids and homologous chromosomes different from each other? A) They are not different. Homologous chromosomes and sister chromatids are both identical copies of each other. B) Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication. C) Homologous chromosomes are identical copies of each other. One sister chromatid comes from the father, and one comes from the mother. D) Homologous chromosomes are closely associated with each other in both mitosis and meiosis. Sister chromatids are only associated with each other during mitosis. E) Sister chromatids are only formed during mitosis. Homologous chromosomes are formed during meiosis.

9 50) A human cell containing 22 autosomes and a Y chromosome is A) a zygote. B) an egg. C) a sperm. D) a somatic cell of a male. E) a somatic cell of a female. Answer directly on the exam for questions #51 – 54 Short Answer Essays : For questions 51 – 53 provide a short answer to the question (1+ complete sentences). Single word or short phrase answers will not receive full credit. You may use drawings as part of your answer. 51. Energy (10 points total) a. (10 points) Explain how ATP performs cellular work. How is the energy from ATP released and transferred to target molecules? Is ATP hydrolysis used to facilitate endergonic or exergonic reactions? ATP performs working in the cell through energy coupling where the exergonic reaction of ATP hydrolysis is used to drive endergonic reactions in the cell. ATP often provides energy to reactions by transferring a phosphate group to a target protein through phosphorylation. 52. Photosynthesis (15 points total) a. (5 points) Distinguish between autotrophic and heterotrophic nutrition. Autotrophic means self-feeder and heterotrophic means other-feeder. An organism that performs autotrophic nutrition is able to make high energy molecules like glucose through anabolic pathways (like photosynthesis) that transfer energy from the environment (such as sun energy) to food molecules. An organism that uses heterotrophic nutrition breaks down high energy molecules through catabolic pathways (like cellular respiration) and transfers the released energy to ATP which is used to perform work in the cell. b. (10 points) Describe the two main stages of photosynthesis in general terms. What are the reactants and products of each stage? How is energy transferred from the beginning of the first stage to the end of the second stage? How are the two stages connected to one another? The first stage of photosynthesis is the light reaction where sunlight energy is used to split water and excites the released electrons. These high energy electrons are used to drive the production of ATP through photophosporylation and reduce NADP+ to make NADPH. The Calvin cycle uses the ATP and NADPH produced by the light reactions to fix carbon atoms by reacting carbon dioxide with RUBP, energize endergonic reactions by ATP hydrolysis, and reduce the carbon molecules to convert them into small G3P sugar molecules using NADPH. 53. Cell Division (10 points total) a. (10 points) Describe the process of synapsis during prophase I and explain how crossing-over (genetic recombination) occurs. Be specific and make sure to include a description of changes to the chromosomes. Synapsis is the fusion of homologous chromosome pairs during Prophase I. This pairing of chromosomes allows for exchange of DNA between non-sister chromatids through the process of crossing over. Crossing over results in genetic recombination between the chromatids.

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10 54. Cellular Respiration (15 points total) Below is a summary figure of cellular respiration. Use the following terms to label the boxes in the figure. Not all of the terms will be used. ATP NADPH NADH Stroma Matrix Calvin Cycle Pyruvate Oxidation Glucose RUBP Pyruvate G3P CO 2 O 2 Cytosol ADP Chemiosmosis Acetyl CoA Electron Transport Chain Glycolysis Photophosphorylation Light Reaction Citric Acid Cycle Thylakoid

BIOL150_Fall19_Exam_2_Key

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