BICD100Exam%202Fall2008answerkey - BICD 100 Fall 2008...

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Unformatted text preview: BICD 100, Fall 2008 Examination - 2 Dr. J. B. Ghiara The exam consists of 6 pages including this cover page. Rules: Please refer to your syllabus for details on Exam and Grading policies. 1. The Exam will end promptly at the end of the assigned time. 2. Your pens, #2 pencils and an ID card (student or driver's license) are the only personal items you may have with you during the exam. 3. Please only use pencils to fill in the circles on the scantron forms. If you use ink, the scantron machine will mark your answers wrong and your score will be zero. If you change an answer, erase it very clearly. If the machine detects two answers, it will mark it wrong. 4. Cheating will not be tolerated and will result in a failing grade for this course. When you are done with your exam, bring this exam and your scantron form to one of the TAs. You will need to show your ID to the TA and get checked off the roll sheet before you can leave. This is proof that you took the exam. © J. B. Ghiara, November 2008. All 6 pages of this exam are copyrighted material and the property of Dr. J.B. Ghiara. All copying and/or posting of this material is strictly prohibited. Please fill in your names and Student ID numbers on this page and on page 6. LAST NAME:__________________________________ FIRST NAME:__________________________________ STUDENT I.D. #:_______________________________ (5 point deduction if the names of students on both sides are not filled in) Full Name of student sitting to my left is: __________________________ Full Name of student sitting to my right is: __________________________ Now please fill in your name and student ID number on the back of the scantron form. You need to fill in the corresponding circles otherwise you will not get a score for this exam. Original scantron forms will not be returned to you. A copy of pages 5 and 6 will be handed back in class next week, on Tuesday. Now that we are done with that, GOOD LUCK! STUDENT INITIALS:____________________ Section A: Please answer questions 1 through 11 on the scantron form. Mark only one answer (the best answer). Numbers in parentheses at the end of the questions represent the maximum points awarded for those questions. (13 points) Answer questions 1 and 2 based on the information given below: Two gene loci, P and Q, are unlinked (and thus assort independently). Allele P is dominant over allele p but alleles Q and q show incomplete dominance. Indicate the probabilities of producing the following: 1. A Pq gamete from an PpQq individual? A) 1/16 B) 1/8 C) 1/4 D) 1/2 E) 3/4 2. How many different phenotypes could occur in children of parents, both of whom have the PPQq genotype? (1) A) 2 B) 3 C) 4 D) 6 E) 9 (1) Answer questions 3, 4, and 5 based on the information given below: In Mandells, the allele for huge ears is incompletely dominant over the allele for tiny ears, and thus heterozygous Mandells have normal sized ears. What ratios of ear sizes would you expect to see among progeny generated from the following crosses of Mandells? 3. Huge ears × Normal ears A) 100% normal ears B) 50% huge ears; 50% normal ears C) 100% tiny ears D) 25% huge ears; 50% normal ears; 25% tiny ears E) 100% huge ears (1) 4. Normal ears × Normal ears A) 100% normal ears B) 50% normal ears; 50% tiny ears C) 100% tiny ears D) 25% huge ears; 50% normal ears; 25% tiny ears E) 100% huge ears (1) 5. Tiny ears × Normal ears A) 100% normal ears B) 50% normal ears; 50% tiny ears C) 100% tiny ears D) 25% huge ears; 50% normal ears; 25% tiny ears E) 100% huge ears (1) Answer questions 6, 7, and 8 based on the information given below: Fruit color in eggplants is inherited as an incompletely dominant characteristic: Homozygous dominant plants produce purple fruit, heterozygotes produce violet fruit and homozygous recessive plants produce white fruit. You cross two eggplants with violet fruit. Among the offspring, 20 bear purple fruit, 47 bear violet fruit and 33 bear white fruit. You want to perform a chi-square test, to compare the observed 2 STUDENT INITIALS:____________________ numbers with the ratio you expect for incomplete dominance and determine if the difference between observed and expected values could be a result of chance. 6. What are the expected values you would need to use in the formula to calculate your χ2 statistic? (1) A) +5, -3 and +8 for purple, violet and white fruit, respectively B) 53 and 47 for heterozygous and homozygous fruit, respectively C) 20%, 47% and 33% for purple, violet and white fruit, respectively D) 20, 47 and 33 for purple, violet and white fruit, respectively E) 25, 50 and 25 for purple, violet and white fruit, respectively 7. For the above experiment, your calculated χ2 value should be: A) 187/50 B) 0.98 C) 0.16 D) 16 E) (0.10)2 8. Your calculated χ2 value turns out to be less than 5.991, the 5% critical value for the correct number of degrees of freedom for this experiment. You could say (1) A) the difference between the observed and expected numbers of offspring is due to something other than chance alone B) the difference between the observed and expected numbers of offspring could be due to chance alone (2) Answer questions 9, 10 and 11 based on the information provided in each question: 9. The genotype of a woman who has AB negative (AB -) blood is: (HINT: Assume the alleles d and h have the same meaning as we used in our lecture on blood types) (1) A) ABhh B) AaBbdd C) ABdd D) Both A and C are possible E) Both B and C are possible 10. A woman with A negative (A-) blood is pregnant and the fetus’s father has A positive (A+) blood. Which of the following is true? (1) A) The father is Rh+ so the fetus has to be Rh+ B) Unless the pregnant mother is given Rhogam, she will develop anti-Rh antibodies (usually after childbirth but this could happen earlier if there is bleeding at the placenta) C) The fetus could be Rh – and if so, there would be no risks due to the Rhesus factor associated with this pregnancy. D) Both B and C are possible. E) The father only contributes sperm. The blood is made in the fetus so it will have A- blood and all will be well. 11. Ptosis (droopy eyelid) may be inherited as a dominant human trait. Among a group of people who are heterozygous for the ptosis allele, 10 have ptosis and 30 have normal eyelids. What is the penetrance for ptosis? (2) A) 100% B) 75% C) 50% D) 33.3% E) 25% 3 STUDENT INITIALS:____________________ Section B: Please answer questions 12 through 21. Mark the correct answer for each of these True/False questions on your scantron forms. Bubble in A for true, B for false. (11) 12) In Mendel’s dihybrid cross, if the probability of getting wrinkled green seeds was 1/16 and the probability of getting wrinkled yellow seeds was 3/16, we can say that the probability of getting wrinkled seeds regardless of color would be 1/4. T 13) In diploid individuals, the phenotype encoded by a recessive, hemizygous allele will be observed. T 14) A reciprocal cross can be used to determine whether an individual is homozygous or heterozygous for autosomal alleles. F 15) While the XO genotype results in a woman with Turner’s syndrome, in Drosophila, the XO genotype gives rise to a male fly. T 16) A person with the genotype XYY will have no Barr bodies in their cells. T 17) The coefficient of the second term in the expansion of the binomial (a+b)9 will be 9. T 18) Mullerian ducts die out in male embryos because the testes produce MIS. T 19) Male-limited precocious puberty is an example of a sex-limited characteristic. T 20) Human X and Y chromosomes do not have any homologous regions. F 21) Women (XX) that are heterozygous for an X-linked gene have patches of cells that express one allele and patches of cells that express the other. T 22) In mice, the allele Y is dominant for coat color (Yellow) but recessive for lethality so heterozygous parents will produce viable (living) offspring in the ratio 2:1 (2 yellow:1 non-yellow) [Assume a very large number of progeny in a series of crosses] T 4 STUDENT INITIALS:____________________ Section C: Please answer the following short answer question. (6) 23) Mating between a white-eyed fruit fly and a heterozygous, red-eyed (wild type) female results in 101 offspring. What is the probability that the F1 generation will have 100 red-eyed males? HINT: Do not use the binomial expansion to solve this problem. Use the formula with the factorials! When answering the following parts of question 23, show your work explicitly writing out any Punnett squares/ formulas/ calculations. a. Write the genotypes of the parents (the white-eyed and red-eyed flies that mate, as stated above. Assume the male has an X and a Y chromosome and the female has two X chromosomes, as normally expected) (1) XXw b. Draw a Punnet Square, clearly showing the possible genotypes of the progeny. (2) Xw X XXw XY Xw c. Y XwXw XwY Write the formula (the one with the factorials) that you would use to calculate the probability of the F1 generation having 100 red-eyed males (remember the total number of offspring is 101), with all the correct numbers included (i.e. replace n, a, b, s and t with the numbers you would need to actually calculate the probability). [As long as all the correct numbers are in place, you do not need to calculate the final answer.] (3) a=red-eyed male = ¼ b = not red-eyed male = 3/4 n! asbt s!t! = 101! x (1/4)100(3/4)1 100!1! 5 STUDENT INITIALS:____________________ Sections A and B C Total Points 24 6 30 Your Score Grader Scantron machine LAST NAME:______________________ FIRST NAME:____________________ STUDENT I.D. #:_______________________________ Original scantron forms will not be returned to you. A copy of Pages 5 and 6 will be handed back in class next Tuesday. If you would like to pick up pages 5 and 6 of the exam some time after it has been distributed in class, please sign below to give permission for it to be left for you on the shelves outside my office (3080A York Hall). _________________ Student Signature NAME OF MY TA:____________________ 6 ...
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