Exam 1 test without key for chapters 25-28 PDF

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This is the practice exam for the first test in class for 2021. It was self-made and reflected what we were taught in class at uga with Dr. lemon....

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1. (1 pt) True or false. Mendel's first law means that segregation of alleles of one gene is independent of the segregation of alleles of a second gene. False : The two alleles for each trait segregate equally during gamete formation 2. In guinea pigs, rough coat (R) is dominant to smooth coat (r). Pure-breeding rough-coated guinea pigs were crossed with pure-breeding smooth-coated guinea pigs and the F1 progeny were then crossed to generate 200 F2 progeny. In these F2 progeny, some had rough coats and some had smooth coats. 2A. (2 pts) Which statement is correct about the cross used to generate the F2 progeny? (a) It was a backcross. (b) It was an intercross. (c) It was an outcross. (d) It was a testcross. 3. (2 pts) In a type of plant, smooth seeds (S) are dominant to wrinkled seeds (s) and tall plants (T) are dominant to short plants (t). A pure breeding tall plant with wrinkled seeds was crossed to a pure breeding short plant with smooth seeds. The F1 was then crossed to a plant that was short and wrinkled. What proportion of the progeny is expected to be heterozygous for both traits? (a) 1/2 (b) 1/4 (c) 1/8 (d) 1/16 (e) 0 4. (2 pts) In jimson weed, purple flowers (P) are dominant to white (p). Self-fertilization of a particular purple-flowered plant produces 28 purple-flowered and 10 white-flowered progeny. What proportion of the purple-flowered progeny will breed true? (a) 1/2 (b) 1/3 (c) 1/4 (d) 3/4 (e) All of the F2 5. (2 pts) Agouti hair color in wild-type mice results from production of both yellow and black pigment, and is controlled by a dominant allele (A) of the agouti gene. Black mice are homozygous for a recessive allele (a) of the agouti gene. You do a cross of Aa x Aa mice and get six progeny. What is the probability that ALL six progeny will be agouti colored? (a) 3/4 x 6 (b) 2/3 x 6 (c) 3/4^6 (d) 2/3^6 (e) None of the above 6. (2 pts) Which of the following statements is true of polygenic traits? (a) Many polygenic traits display continuous variation. ******Look over***** (b) All polygenic traits fall into discrete classes of phenotypes. (c) Effects of individual genes contributing to polygenic traits are rarely additive. (d) Polygenic traits rarely occur in humans. (e) All of the above are true.

7. In humans there are three unlinked genes that determine different blood types. The I gene has three alleles (IA, IB and i) that determine the ABO blood group system. The MN gene has two codominant alleles (M and N) that determine blood type M, N, or MN. The Rh gene has two

alleles (R and r) that determine Rh positive (Rhpos) vs Rh negative (Rhneg), and R is completely dominant to r. For this question, assume no involvement of the Bombay phenotype. 7. (cont) (3 pts) A woman with “O M Rhneg” blood type has a child with “A MN Rhpos” blood type. Of the following males, which one could be the biological father? (a) I Ai MN rr (b) I B i MN RR (c) ii NN rr (d) ii MM rr (e) I AI A MN RR 8. At the right is a pedigree of a genetically determined trait in humans that has complete penetrance and invariable expressivity. Filled symbols indicate individuals with the trait, open symbols indicate individuals that lack the trait. 8. (cont) (3 pts) If III-2 and III-3 have children together, what is the probability that their offspring will exhibit the trait? (a) 0 (b) 1/4 (c) 1/2 (d) 2/3 (e) 4/9 9. (2 pts) Which is the correct name for microtubule organizing centers at the spindle poles? (a) Centromeres (b) Kinetochores (c) Centrosomes (d) Spindlesomes (e) None of the above

10. (1 pt) A particular species has 18 chromosomes in its diploid cells. How many chromatids per cell would be present after S phase? 18. 36 got wrong bc didn’t read chromatids!!! 11. (1 pt) In the same species as in the previous question, how many chromosomes per cell would be present after the first meiotic division? 9 12. (1 pt) True or false. The spindle apparatus is present in meiotic metaphase I but is not present in meiotic metaphase II. 13. (2 pts) The centromeres of sister chromatids uncouple and the chromatids separate in which meiotic phase? (a) prophase I (b) prophase II (c) anaphase I (d) anaphase II (e) metaphase I (f) metaphase II 14. (1 pt) True or false. Movement of homologous chromosomes to opposite poles at anaphase I of meiosis accounts for Mendel’s 2nd law. ***** right bc independent assortment happens at anaphase 1 after crossing over occurs. 15. (3 pts) Which of the following is the correct order of the five stages of meiotic prophase I? (a) Diakinesis, leptotene, diplotene, zygotene, pachytene (b) Leptotene, zygotene, pachytene, diplotene, diakinesis (c) Zygotene, pachytene, diplotene, leptotene, diakinesis (d) Interphase, prophase, metaphase, anaphase, telophase didn’t look over (e) G1, S, G2

(f) None of the above 16. The five cells shown in figures A – E are all from the same individual and are at different stages of the cell cycle. Choose from the list and write the number that identifies each stage. 1. Anaphase of mitosis 2. Anaphase of meiosis I 3. Anaphase of meiosis II 4. Metaphase of mitosis 5. Metaphase of meiosis I 6. Metaphase of meiosis II 7. Prophase of mitosis 8. Prophase of meiosis I 9. Prophase of meiosis II 10. Telophase of mitosis 11. Telophase of meiosis I 12. Telophase of meiosis II 16. (cont) (1 pt each) Cell A. 12 Cell B. 4 Cell C. 2 Cell D. 6 Cell E. 1 17. Shown below is a list of events in mitosis, which are numbered in random order. 1. Sister chromatids separate and move to opposite poles. 2. Chromosomes align on the midplate of the cell. 3. Kinetochores begin attaching to spindle fibers. 4. Nuclear membrane reforms and chromosomes decondense. 5. Chromosomes condense, and centrosomes migrate to opposite sides of nucleus. 17. (cont) (4 pts) Using the number of each event above, what is the correct order of events? (a) 3 – 2 – 5 – 1 – 4 (b) 1 – 2 – 3 – 4 – 5 (c) 5 – 3 – 2 – 1 – 4 (d) 3 – 2 – 1 – 4 – 5 (e) None of the above 18. In tomatoes, full leaf and narrow leaf are alternative characters, with full (N) dominant to narrow (n). Purple stem and green stem are also alternative characters, with purple (G) dominant to green (g). A plant with full leaves and green stems was crossed to a plant with full leaves and purple stems. The offspring of this cross were: Full leaf, purple stem 31 Full leaf, green stem 29 Narrow leaf, purple stem 8 Narrow leaf, green stem 12 18 (cont) (3 pts) What are the genotypes of the parents? Give a brief explanation of your answer

Nngg x NnGg This is because there is ¼ offspring with narrow leaves even though the parents both have dom trait. Thus they both must be heterozygous for the recessive narrow trait. The green offspring are about ½ of the total and since one parent is known to have gg trait the other must then have Gg in order to get ½ green progeny. 19. In rabbits, two genes control hair length (L and its recessive allele l) and hair color (B and its recessive allele b). F1 progeny were generated from crosses of pure-breeding brown with short

hair and pure-breeding black with long hair. After crossing F1 rabbits, the phenotypes and numbers of F2 progeny were:

19A. (4 pts) In the table above, fill in the genotypes and expected numbers of progeny if the two genes are independently assorting. Give a brief explanation of your answer. On paper 19B. (3 pts) Of the 131 black, short-hair F2 rabbits, how many would you expect to be purebreeding? Give a brief explanation of your answer.

19C. (5 pts) Do a Chi-square test (table at the end of the exam) to test your hypothesis of independent assortment. Show all of your calculations, state the degrees of freedom (df) for this experiment, give the range of P values, and your overall conclusion.

20. (3 pts) A, B, and E are three independently assorting genes that have completely recessive alleles a, b, and e, respectively. From the cross Aa Bb Ee × Aa Bb Ee what is the probability of progeny that have the dominant phenotype for all three genes OR the recessive phenotype for all three genes? Show all of your calculations. 7/16 on paper 24. Six types of extensions to Mendelian inheritance are listed below. For each phrase, write the number for each of the terms numbered 1 through 6. Each phrase has only one correct answer. 1. Epistasis 2. Incomplete penetrance 3. Incomplete dominance 4. Codominance 5. Pleiotropy 6. Variable expressivity

*******Look over this******

24A. (2 pts) 2 Less than 100% of the individual possessing a particular genotype express it in their phenotype. 24B. (2 pts) 1 The alleles of one gene mask the effects of alleles of another gene. 24C. (2 pts) 5 One gene affects more than one phenotype. 25. In snapdragons, red flower color (CR ) is incompletely dominant to white (CW); the CR CW heterozygotes are pink. A red-flowered snapdragon is crossed with a white-flowered one. 25A. (2 pts) What are the genotypes, phenotypes, and ratios of the F2? ¼ red CRCR ¼ white CWCW ½ pink CRCW

26. Chickens have combs that can be in four different morphologies (walnut, single, rose, and pear). When a rooster with a walnut comb was crossed to a hen with a single comb, all the F1 progeny had walnut combs. In the F2 progeny, the following progeny were observed: 110 walnut 35 pea 37 rose 10 single 26A. (2 pts) How many genes are involved in these traits? Explain your answer.

????? 2 genes 2 alleles??

26B. (4 pts) What proportion of pea and rose F2s will breed true (i.e. be pure breeding) for both traits? Explain your answer. ?????

29. You do a cross between two true-breeding strains of plants. One strain has green fruit and the other strain has yellow fruit. All the F1 plants had green fruit, but when these F1s were intercrossed, 9/16 of the F2 plants had green fruit and 7/16 of the F2 plants had yellow fruit. 29A. (2 pts). This phenotypic ratio is a result of what type of gene interaction? (a)Complete dominance (b) Incomplete dominance (c) Complementary gene action (duplicate recessive epistasis) *** look up words*** (d) Recessive epistasis (e) Dominant epistasis

29B. (3 pts). For the yellow F2s, what are the genotypes and the proportions of each genotype in this phenotype class. If you think there is one gene involved, use A and a to represent the dominant and recessive alleles. If you think there are two genes involved, use A and B to represent the dominant alleles, and a and b to represent the recessive alleles.

30. In squash, two independently assorting genes (G and W) control fruit color. At one gene, yellow is dominant to green and the dominant and recessive alleles, respectively, are G and g. At the second gene, the absence of color (white) is dominant to any color, and the dominant and recessive alleles, respectively, are W and w. Squash that were true-breeding for white were crossed to squash that were true-breeding for yellow. The F1 were all white. After selfing the F1 progeny, the phenotypes observed in the F2 progeny are shown below. 238 white 61 yellow 21 green

30 (cont) (5 pts) You want to identify the white F2 squash that will produce either yellow or green or both colors, so you testcross a number of these white F2s. What proportion of white F2s will produce progeny that are yellow and/or green? Explain your answer, including the genotype used for the testcross

12:3:1

Test 2

1. (2 pts) What is Mendel’s first law? A. Dominant factors mask the expression of recessive factors B. Equal segregation of only one allele of each gene to a gamete. C. Independent assortment of different pairs of alleles during gamete formation. D. Peas are the best experimental organism for genetics 2. (2 pts) Shown below is a cross involving four unlinked, autosomal genes (A, B, C, and D). What is the probability of producing a child that is homozygous recessive for gene A but heterozygous for each of the B, C, and D genes? Show your calculations.

Aa Bb cc DD x Aa BB Cc dd

1/16 3. After a cross between two corn plants, the F1 plants all had a dwarfed phenotype. The F2 progeny consisted of 1,207 dwarf plants and 401 tall plants. For the questions below use D for the dominant allele and d for the recessive allele. 3.(cont) (3 pts) What proportion of the dwarf F2 progeny will breed true (i.e. be pure breeding)? Give a brief justification of your answer. 1/3 bc DD is 1 out of the 2 other Dd. Or conditional way ¼ (prob of homo drawf) / ¾ (probb of dwarf) 4. The two parts of this problem refer to inheritance of albinism, which is a complete lack of skin pigment due to a rare, autosomal recessive gene. The trait has complete penetrance and expressivity. For each of the two situations, show all equations needed to calculate the probability.

4A. (2 pts). The woman is albino and the man is normally pigmented but his father was albino. What is the probability of this couple having an albino child? ½ 4B. (2 pts). The woman is normally pigmented but has an albino brother, and the man is normally pigmented but has an albino mother. What is the probability of this couple having nonidentical twins that are both albino girls? 1/8. Wrong didn’t read right don’t expect them to be easy. 5. In Drosophila, two autosomal genes are known to control wing size and eye shape. For wingsize, t is the recessive allele for tiny wings and T is the dominant allele for normal wing

size. For eye shape, n is the recessive allele for narrow eyes and N is the dominant allele for oval eyes. Crosses between true-breeding females with narrow eyes and true-breeding males with tiny wings yielded F1 flies of normal phenotype for both wing size and eye color. F1 flies were intercrossed to generate the phenotypes and numbers of F2 progeny in the table below.

5. (cont) (6 pts) For each phenotype class in the table below, fill in the genotypes and expected numbers of progeny if the genes are unlinked. For genotypes, use the gene symbols T and N to indicate the wildtype alleles for the two genes and t and n to indicate the mutant alleles of the two genes.

6. (2 pts) For the pedigree below, state the most likely inheritance pattern for the disorder. Assume the trait has complete penetrance and expressivity. A. autosomal recessive B. autosomal dominant C. X-linked recessive D. X-linked dominant

(2 pts) In humans the three alleles IA, IB and i constitute a multiple allelic series that determines the ABO blood group system. Could a child of blood type O be the offspring of parents who are of blood type A and blood type B? write yes or no, and write the genotypes of the parent. Yes bacues they can both be recessive for the i allele and thus have a ¼ chance of giving it to their child.

Sally (IV-1) and Jim (IV-2) both had relatives with hypercholesterolemia, a rare genetic disorder. To the right is a pedigree with all of the relatives of Sally and Jim (assume complete penetrance). They want to know the chances that a child of theirs would have this disorder.

8. (cont) (6 pts) What is the probability that the first child of Sally and Jim would have this disorder? Show all necessary equations and identify each individual used in your calculations.

9. In guinea pigs, hair length and hair pigment are controlled by two genes, A and B, respectively. Alternative alleles of the hair length gene are A and a, and alternative alleles of the hair pigment gene are B and b. A pure-breeding white female with short hair was mated to a yellow male with long hair, and all the F1 were cream-colored with short hair.

Several F1s were intercrossed and resulting F2 progeny were: 29 yellow with short hair, 11 yellow with long hair, 62 cream with short hair, 19 cream with long hair, 29 white with short hair, 12 white with long hair

9A. (4 pt) Are these two genes independently assorting (unlinked). Explain your answer Yes they are 2 genes. Independently assorting because the traits that you get are inline with those if you had incomplete dominance. B. (cont) (2 pts). For the hair pigment gene B, is the inheritance completely dominant, incompletely dominant, or co-dominant? Explain your answer. heterozygous Bb shows incomplete dominace and combines the color of white and yellow to get cream.

10. In chickens, one or more genes are responsible for causing combs to have different morphologies (walnut, single, rose, and pear). When a rooster with a walnut comb was crossed to a hen with a single comb, all the F1 progeny had walnut combs. In the F2 progeny, the following progeny were observed: 110 walnut 35 pea 37 rose 10 single

10A. (2 pts) How many genes are involved in these traits? 2 genes likely involved because the first f1 generation has heterozygous individuals and the f2 is at a 9:3:3:1 ratio which is indicative of 2 genes. Explain your answer

10B. (4 pts) What proportion of walnut F2s will breed true (i.e. be pure breeding) for both traits? (Hint: consider only the walnut progeny). Explain your answer. 49 11. (2 pts) In rabbits, C = agouti coat color, ch = Himalayan, and c = albino. The three alleles constitute a multiple allelic series and the gene is autosomal. The agouti C is dominant to the two other alleles, and c is recessive to ch . After crossing an agouti female with a Himalayan male,

you obtained Himalayan, agouti, and albino progeny in a 1:2:1 ratio. What are the genotypes of the two parents? C c x ch c

12. In mice, agouti (A) and albino (C) are unlinked genes that control coat color. The phenotypes for different genotypes involving these two genes are shown below. AY AY, lethal AY A, viable and yellow AA, viable and agouti-colored CC or Cc, have pigment cc, no pigment

12. (cont) (6 pts) What genotypes, phenotypes, and phenotypic ratios of viable offspring would you expect from intercrossing AY A Cc mice? ???

13. The painted tongue garden flower comes in several different colors. You cross a truebreeding yellow strain with a true-breeding blue strain, and the F1 progeny are all lavender. After selfing the F1, you obtain the following F2 progeny 440 lavender 140 blue 188 yellow

13A. (2 pts) What inheritance pattern is responsible for these proportions of F2 progeny? A. Recessive epistasis 9:3:4 B. Dominant epistasis C. Complete dominance D. Incomplete dominance E. Complementary gene action (duplicate recessive epistasis)

13B. (6 pts) Use a chi-square test and the table below to determine if the results you observed are consistent with the inheritance pattern from part A. Show all necessary calculations. Be sure to state the degrees of freedom for your test and the range of P values, in addition to your conclusion about linkage 0.34 and thus 0.9-0.5 which is greater than 0.5 so fail to reject null hypothesis

14. (2 pts) Which of the following terms is defined as the percentage of individuals with a given allele who exhibit the phenotype associated with that allele. A.Co-dominance B. Penetrance C. Suppression D. Expressivity E. none of the above 15. (2 pts) Which of the following statements are true of polygenic traits?

A. Polygenic traits display continuous variation. B. Polygenic traits fall into discrete classes of phenotypes. C. Effects of individual genes contributing to polygenic traits are rarely additive. D. Genes that contribute to polygenic trait are never linked. 16. (2 pts) In which stage of meiosis does uncoupling of the centromeres of sister chromatids and separation of chromatids occur? A. prophase I B. telophase I C. anaphase I D. anaphase II E. metaphase II F. diakinesis

17. Shown below is a list of events in mitosis, which are numbered in random order. 1. Sister chromatids separate and move to opposite poles. 2. Chromosomes align on the midplate of the cell. 3. Kinetochores begin attaching to spindle fibers. 4. Nuclear membrane reforms and chromosomes decondense. 5. Chromosomes condense, and centrosomes migrate to opposite sides of nucleus.

17. (cont) (3 pts) Using the number of each event above, what is the correct order of events in mitosis? 5-3-2-1-4

18. (...