Scientific Method. Name: NetID: Exam 1 Version 1 September 12, 2017 Dr. A. Pimentel

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1 Name: NetID: Exam 1 Version 1 September 12, 2017 Dr. A. Pimentel Each question has a value of 4 points and there is a total of 156 points in the exam. However, the maximum score of this exam will be capped at 150 points. Instructions: Select the BEST answer for each question Scientific Method 1- Insulin is a peptide hormone that reduces the amount of sugar in our bodies. What is the general sequence of cell-signaling events upon insulin binding to its receptor? A. 1. Receptor activation, 2. response, 3. signal transduction B. 1. Signal transduction, 2. response, 3. receptor activation C. 1. Response, 2. signal transduction, 3. receptor activation D. 1. Receptor activation, 2. signal transduction, 3. Response E. None of the answer choices are correct. 2- The mitogen-activated protein kinase (MAPK) are enzymes that are involved in a variety of cellular processes ranging from cell growth to cell survival. A scientist has identified MAPK-A, MAPK-B, and MAPK-C that appear to be involved in a cell survival pathway. What should the scientist do in order to determine the order in which these kinases act? A. Design an experiment using control cell lines to determine the order of the kinases. B. Design an experiment using cell lines with random mutations, which may affect a variety of processes in addition to mutating the kinases. C. Design an experiment using cell lines with specific mutations, which either permanently mutates the respective kinases to be either always on or always off. D. Choices B and C are both correct E. All of the answer choices are correct.

2 3- The scientist makes a statement stating, In order for the cell survival pathway to function properly, the MAPK-C kinase must function before MAPK-B. This is an example of a(n). A. Observation B. Hypothesis C. Prediction D. Experiment or new observation E. Theory 4- The scientist performed some initial experiments and she determined that MAPK-C functions before both MAPK-A and MAPK-B. She still does not know the proper order of MAPK-A and MAPK-B. These statements are an example of a(n). A. Observation B. Hypothesis C. Prediction D. New observation E. Experiment 5- The scientist determines that MAPK-C is present in an always on form, MAPK-A in an always off form, and MAPK-B in wild-type (normal) form. She believes that if she replaces the always off MAPK-A with a wild-type MAPK-A in a new experiment, it will result in the activation of wild-type MAPK-B. These statements are best described as an example of a(n). A. Observation B. Hypothesis C. Prediction D. Experiment or new observation E. Theory

3 6- After much research, the scientist confirmed and concluded that the proper order of the signaling pathway is MAPK-C MAPK-A MAPK-B. When MAPK-C is mutated to an always off form and MAPK-A is mutated to an always on form, what is activity of MAPK-B when the signal upstream MAPK-C is either present or absent? A. Signal present: ON, Signal absent: ON B. Signal present: OFF, Signal absent: OFF C. Signal present: ON, Signal absent: OFF D. Signal present: OFF, Signal absent: ON E. None of the answer choices are correct. 7- How does a scientific theory differ from a scientific hypothesis? A. Theories are proposed to test scientific hypotheses. B. A theory is an explanation for a very general phenomenon or observation that has been tested repeatedly; a hypothesis is an explanation about an observation. C. A hypothesis is an explanation for a very general phenomenon that has been tested over and over again; theories pertain to more specific issues. D. Theories define scientific laws; hypotheses are used to set up experiments. E. Hypotheses define scientific laws; theories are used to set up experiments. Amino acids are synthesized in a series of biochemical steps called metabolic pathways. The pathway to produce the amino acid arginine starts with a basic precursor molecule. The precursor molecule is processed by Enzyme 1 and gives rise to the first intermediate molecule called ornithine. It was also known that the molecule produced after ornithine is citrulline. Citrulline is finally used by Enzyme 3 to produce arginine. While the order of the molecules to produce arginine was clear, scientists knew little about the enzymes that are required to produce each of the intermediate molecules. They knew that three enzymes were involved in the pathway and only the position of Arg1 ( Enzyme 1 ) was known. The other two enzymes were ArgY and ArgW. Scientists decided to determine the correct order of enzymes ArgW and ArgY by mutating cells to produce cell lines in which either ArgY or ArgW was permanently inactive.

4 8- In order to inactivate the enzyme certain mutations should be created. This mutation must be done in which of the following molecules? A. Enzyme B. Proteins C. RNA D. DNA E. Carbohydrates 9- Which of the following is a plausible hypothesis? A. Ornithine ArgY Arginine ArgW Citrulline B. Ornithine ArgW Citrulline ArgY Arginine C. Precursor Enzyme 1 Ornithine ArgW D. Precursor ArgW Ornithine Enzyme 1 E. Arginine ArgY Citrulline ArgW Ornithine Cell Theory 10- Which of the following statements violate modern cell theory? A. All known living things are made up of one or more cells. B. Cells store hereditary information in the form of RNA and this is passed from cell to cell during cell division. C. Cells store hereditary information in the form of DNA and this is passed from cell to cell during cell division. D. All cells arise from pre-existing cells by division E. All of the answer choices are correct.

5 11- Fact: Photosynthesis is the process by which cells synthesize its own food using sunlight. Assertion Photosynthesis is an example of how energy flows in a living organism. Because Reason All plants have a common ancestor. 12- Assertion Because Reason All living organism are composed of cells. Cell division is the process by which cells divide and pass their DNA to their offspring. A. Assertion true, Reason true, Reason is the correct explanation B. Assertion true, Reason true, Reason is the correct explanation C. Assertion true, Reason false D. Assertion false, Reason true E. Assertion false, Reason true

6 Theory of Evolution 13- In evolution, a gene pool refers to. A. A group of individuals of the same species living in the same area at the same time. B. The total amount of gene variants in a population. C. A trait that increases the fitness of an individual in a given environment. D. the ability of an individual to produce offspring. E. None of the answer choices are correct. 14- Which of the following statement(s) is correct? I. Artificial selection selects traits based on human preference II. Natural selection chooses traits based on improving an organism s fitness III. Artificial selection does not necessarily improve fitness A. I, II B. I only C. III only D. I, II, III E. II only 15- The saguaro cactus is a native plant to the Sonoran Desert. In order to survive water shortage, young saguaro cacti grow under the shade of a nurse tree. This unique characteristic of saguaro cacti helps to increase their. A. Natural Selection B. Adaptation C. Evolution D. Fitness E. Artificial Selection

7 16- Assertion Adaptation refers to a trait that increases the fitness of an individual in a particular environment. Because Reason Under specific environmental pressures, some genetic traits that increase the fitness of individuals are more likely to be passed on. Samantha adores cats regularly rescues stray/mud cats from her community and takes them to the local animal rescue facilities so that they can be properly cared for and a new home can be found for them. One morning she rescues a litter of kittens and notices that one of them looks remarkably different from the rest. This kitten had extremely short legs but looks normal otherwise. The person called it Munchkin and decided to keep it because it looks cute. She was so attached to this munchkin that she decided to mate it and find out whether any offspring were born with the same trait. After various attempts, she got a couple of additional kittens with the same characteristic. She decided to keep mating those individuals with shorter legs until she could develop a new pure breed, which she called Munchkin.

8 17- She was able to develop the Munchkin breed because: A. She was persistence B. Shorter legs in cats increase their fitness C. The shorter leg trait was encoded in the DNA D. The shorter leg trait was encoded in the protein E. The shorter leg trait was encoded in the RNA 18- The description in the paragraph above is an example of. A. Natural selection B. Artificial selection C. Fitness D. Adaptation E. Genetic pool 19- The successful establishment of the Munchkin breed was possible because. A. There are genetic differences between the cat population B. Cats like to breed a lot C. There was not a selective pressure D. The size of the legs increases their fitness E. The size of their legs increases their adaptation to the city Molecules 20- Molecules that contain are able to form hydrogen bonds with water and easily dissolve in water. A. Non-polar covalent bonds B. Polar covalent bonds C. Hydrophobic interactions D. Dispersion forces E. None of the answer choices are correct

9 21- Naturally occurring Uranium is Uranium-238. The number refers to the atomic mass. However, for nuclear weapons to be the most catastrophic, Uranium-235, an isotope of natural Uranium, is used. What is the difference between Uranium-238 and Uranium-235? A. Uranium-238 has 3 more protons than Uranium-235 B. Uranium-238 has 3 more neutrons than Uranium-235 C. Uranium-235 has 3 more electrons than Uranium-238 D. Uranium-238 has 3 more electrical charges than Uranium-235 E. Uranium-235 has 3 more neutrons than Uranium Which of the following has the biggest effect on the chemical properties of an atom? A. The number of neutrons B. The mass number C. The number of electrons in the valence shell D. The number of orbitals the atom contains E. Whether or not the atom has protons 23- Assertion If atoms of fluoride (F) and radium (Ra) engaged in a chemical reaction, they will form a polar covalent bond. Reason There is a huge difference in the electronegativity value between fluoride (F) and radium (Ra).

10 Water 24- In the figure above, all of the molecules are linear monosaccharides. Based on the chemical structures shown in the figure, determine which monosaccharide will be the least soluble in water. 25- Assertion Because Reason The water molecule has a neutral ph. During the dissociation of the water molecule, equal number of hydrogen ions and hydroxide ions are produced.

11 ph 26- Fact: Human urine has a ph of 6, while the stomach acid has a ph of 2. Assertion The environment in the stomach is more acidic than typical human urine. Because Reason Compared to the urine, the stomach acid has a factor of more H+ (protons) than urine. 27- Industrial emissions contain toxic gases such as sulfur dioxide (SO 2) and nitrous oxide (NO). When these gases react with water in the atmosphere, they form sulfuric and nitric acids. These chemicals combine with rainwater and fall to the ground as acid rain (ph 4) and cause major environmental damages. When acid rain falls into ocean water (ph 8), the ph of the ocean decreases to 6, leading to toxic living conditions for marine life. Which of the following statements below is correct? A. The ocean water after acid rain contains approximately two times more [H+] than before acid rain. B. The ocean water before acid rain contains approximately two times more [H+] than after acid rain. C. The ocean water after acid rain contains approximately one hundred times more [H+] than before acid rain. D. The ocean water before acid rain contains approximately one hundred times more [H+] than after acid rain. E. The ocean water after acid rain contains approximately one thousand times more [H+] than before acid rain.

12 Proteins 28- Which of the following functional groups are found in nucleotide above? I.Phosphate group II. Hydroxyl group III.Carboxyl group IV. Amino group V.Carbonyl group A. I, II B. II, IV, V C. III, IV, V D. I, III, V E. I, II, IV 29- Which of the following best summarizes the relationship between dehydration reactions and hydrolysis? A. Dehydration reactions break down polymers and hydrolysis reactions create polymers. B. Macromolecular synthesis occurs through the addition of water and digestion occurs through the removal of water. C. Dehydration reactions can occur only after hydrolysis. D. Hydrolysis creates monomers, and dehydration reactions break down polymers. E. Dehydration reactions assemble polymers and hydrolysis reactions break down polymers.

13 Nucleic Acids 30- Assertion During RNA polymerization, RNA polymerase facilitates the formation of a phosphodiester bond. Because Reason In the RNA sequence 5 -AAUGC-3, the 3 hydroxyl group of guanine forms a phosphodiester bond with 5 phosphate group of uracil. 31- Which of the following statements about DNA and RNA is false? A. DNA is more stable relative to RNA B. The nucleotides in DNA and RNA can both form hydrogen bonding interactions C. DNA and RNA are both synthesized in the 5 to 3 direction D. Nucleic acids in the DNA contain deoxyribose sugars and nucleic acids in RNA contain ribose sugars E. All of the answer choices are correct. 32- If 30% of a double-stranded DNA molecule is composed of Guanine, what percent of Thymine is present in the DNA? A. 20% B. 30% C. 40% D. 50% E. 60%

14 Transcription 33- What is the proper order of events in which a pre-mrna is converted into a mature mrna? 1. 3 poly(a) tail 2. Splicing of introns and exons 3. 5 cap A. 1, 2, 3 B. 1, 3, 2 C. 3, 2, 1 D. 3, 1, 2 E. 2, 1, Evolutionarily, alternative splicing has enabled eukaryotic cells to? A. Create more unique protein coding messages from a given gene B. Create less unique protein coding messages from a given gene C. Maintain the same amount of protein coding messages for a given gene D. Reduce the size of their genome as more proteins can now be encoded for with less physical genes E. Both A and D are correct 35- Assertion In prokaryotes, transcription stops when RNA polymerase encounters a transcription termination signal. Because Reason Formation of RNA hairpin structure causes RNA polymerase to dissociate from DNA in prokaryotes.

15 36- Assertion Because Reason During transcription, the template is read from the 3 to 5 but the mrna is synthesized in the 5 to 3 direction. During transcription, the growing nucleic acid contains a ribose sugar and uracil nucleotide. 37- Assertion Because Reason If a RNA molecule contains 30% cytosine then this molecule must contain 30% guanine, 20% uracil and 20% adenine The RNA molecule contains uracil instead of thymine

16 38- A mutation caused by radiation in a prokaryotic organism destroys the -10 box of the promoter. Select the statement that correctly describes the most likely consequence of this mutation. A. The general transcription factor will no longer bind to the promoter. B. The transcriptional activator proteins will no longer bind to the promoter. C. The mediator protein will no longer bind to the promoter. D. The DNA will not bend to bring the enhancers closer to the promoter. E. The sigma subunit will no longer bind to the promoter. Extra Credit: 39- What is the correct mrna sequence synthesized based on the following template DNA sequence: 5 -AGTGCCTGATCT-3? A. 5 -AGUGCCUGAUCU-3 B. 5 -AGATCAGGCACT-3 C. 5 -AGAUCAGGCACU-3 D. 5 -TCACGGACTAGA-3 E. 5 -UCACGGACUAGA-3 Electronegativity Table:

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