CSS 350 Midterm #2, 4/2/01

Transcription

1 6. In corn three unlinked dominant genes are necessary for aleurone color. The genotypes B-D-B- are colored. If any of these loci is homozygous recessive the aleurone will be colorless. What is the expected phenotypic frequency distribution (phenotypes and their frequencies) of the F2 offspring of this F1 genotype: BbDdRR 7. In the common daisy the genes A and a, B and b represent two pairs of alleles acting on flower color. Only the A-B- genotypes have color. Predict the genotype and phenotype of the F1 of a cross between two colorless plants, one homozygous for the 'A' allele and the other homozygous for the 'B' allele. 8. Genes Q and R are 20 map units apart. What is the expected frequency distribution of gametic genotypes (list all gametic genotypes and their expected freqeuncies)of a plant with the genotype QR/qr? In peas, tall (T) is dominant to short (t), red flowers (R) is dominant to white flowers (r), and wide leaves (W) is dominant to narrow (w). A tall, red, wide plant is crossed to a short, white, narrow plant and the progeny are as follows: tall red wide 400 tall white wide 99 short red wide 101 short white wide What is the genotype (expressed to indicate the linkage arrangement, i.e. _ / _ ) of the tall, red, wide parent plant used in the testcross? Page 1

2 10. Name one area of the world where the 'Green Revolution' took place. 11. Cases where the relative phenotypic effects of alleles at one locus depend on the genotype at one or more other loci are instances of: A. epistasis. B. epigenetics. C. dominance. D. co-dominance. E. incomplete dominance. 12. are caused by changes in nucleotide sequences. A. phenotype B. genotypes C. mutations D. traits E. characters 13. When the same gene is related to flower color and stem color, it is an example of : A. pleiotropy. B. co-dominance. C. incomplete dominance. D. complete dominance. E. penetrance and expressivity. 14. If two or more forms of the same gene exist, the different forms are called: A. incomplete dominance. B. penetrance and expressivity. C. pleiotrophic. D. alleles. E. dihybrid. 15. The stage of mitosis when chromosomes condense to form rod-shaped structures visible under the microscope is called: A. interphase. B. prophase. C. metaphase. D. anaphase. E. telophase. Page 2

3 16. The stage of mitosis when sister chromatids separate from each other and migrate to opposite poles of a cell is called: A. interphase. B. prophase. C. metaphase. D. anaphase. E. telophase. 17. During which of the following stages of the cell cycle would a chromosome consist of only a single chromatid? A. G1 B. G2 C. mitotic prophase D. mitotic metaphase E. all of the above 18. Crossing over between homologous chromosomes occurs at which of the following stages of meiosis? A. S phase B. prophase I C. metaphase I D. anaphase I E. prophase II 19. At which of the following stages of meiosis would homologous chromosomes be paired? A. prophase of meiosis I B. prophase of meiosis II C. metaphase of meiosis I D. metaphase of meiosis II E. a and c are correct 20. The chromosomal structure to which spindle fibers attach during the mitotic divisions is referred to as a: A. chromatid. B. centrosome. C. kinetochore. D. metaphase plate. E. arm Page 3

4 21. Mitosis results in in chromosome number while meiosis results in chromosome number. A. a doubling of, no change in B. no change in, no change in C. a reduction by half in, no change in D. no change in, a doubling of E. no change in, a reduction by half in Use the following information to answer questions Consider the 'R' and 'S' genes, where R is dominant to r, and S is dominant to s. A testcross of a plant with genotype RrSs had the following phenotypic frequency distribution: R_S_ 99 rrs- 398 R_ss 402 rrss What is the recombination frequency between these two genes? 23. The 'R' and 'S' loci in the RrSs plant used in the testcross appear to be: A. on the same chromosome in coupling (cis) phase B. on the same chromosome in repulsion (trans) phase C. unlinked D. 50 map units apart E. epistatic F. useless 24. Which of the following processes can generate recombinant gametes? A. Segregation of alleles in a heterozygote. B. Crossing over between two linked heterozygous loci. C. Independent assortment of two unlinked heterozygous loci. D. b and c E. a, b and c T F 25. The first division that a plant zygote undergoes is mitosis. T F 26. A cell with 40 chromatids at the beginning of mitosis has 20 chromosomes. Page 4

5 T F 27. In meiosis, one nucleus divides into four nuclei. T F 28. Homologous chromosomes form pairs in Metaphase of mitosis. T F 29. Discontinuous traits can be classified into distict categories of phenotype. T F 30. Many traits are influenced by both major genes with large effects, and modifier genes with small effects. T F 31. 2N is shorthand for the number of chromosomes in a gamete. T F 32. Two chromosomes are homologous because they are descendents of a common progenitor chromosome. T F 33. DNA replication must occur between Meiosis I and Meiosis II. T F 34. The primary evidence of linkage between two genes is a preponderance of parental gametes from a dihybrid. T F 35. One cm = 1 map unit = 1% recombination frequency. Page 5

6 Answer Key for Test "rw2.tst", 4/5/01 No. in No. on Q-Bank Test Correct Answer Phenotype: 9 Color; 7 Colorless Genotype Phenotype AaBb Colored QR 40%, qr 40%, Qr 20%, qr 20% TRW/trW Indian subcontinent or its countries, Mexico, others? A C A D B D A B E C E % B D T T T F T T ? T F T T Page 1

7 Statistics for Test "rw2.tst". Total questions: 30 Key Word Total Difficulty Level Total None Total None 30 None 15 Free Format True or False Multiple Choice Matching 0 4 1