<p>SBI 3U Chapter 6 Test Name: ______</p><p>Knowledge/Understanding Communication Thinking & Inquiry Application /15 /6 /15 /6</p><p>PART A: MULTIPLE CHOICE [K/U: 1 mark each = 5 marks]</p><p>Circle the choice that best answers the question.</p><p>1. A test cross is one in which the organism with the unknown genotype is mated with an organism that is a. heterozygous for the trait b. homozygous dominant for the trait c. homozygous recessive for the trait d. of the same genotype as the organism being tested e. of the opposite genotype to the organism being tested</p><p>2. When two alleles for a given gene are both equally and fully expressed, the alleles are said to be a. Incompletely dominant b. Codominant c. Linked d. Homozygous dominant e. Dominant</p><p>3. Which of the following is/are true for alleles? a. They can be identical or different for any given gene b. They can be dominant or recessive c. They can represent alternative forms of a gene d. Only A and B are correct e. A, B, and C are correct</p><p>4. What is the probability that a PpQQRrSs parent will produce a gamete that is PQRS? a. 1/2 b. 1/4 c. 1/8 d. 1/16 e. 1/32</p><p>5. If 3/4 of the offspring from any experimental crosses showed only the dominant characteristics, the parents of those particular offspring are a. one homozygous dominant, one recessive b. one heterozygous, one homozygous dominant c. both heterozygous d. both homozygous dominant e. both homozygous recessive PART B: MATCHING [K/U: 1 mark each = 10 marks]</p><p>Match the following terms with the correct definition or example. Note: there will be 4 choices left over. DO NOT use a number/word more than once!</p><p>1. Heredity _____ produced by the process of crossing over 2. Mendel _____ the process of passing traits from one generation to the next 3. Recombinants _____ when a blending occurs in heterozygotes 4. 9:3:3:1 _____ the allele expressed in a heterozygote 5. pure-breed _____ a trait that is only visible when it is homozygous 6. monohybrid cross _____ when there are more than two possible alleles for a given gene 7. Recessive _____ organism that produces an offspring identical to the parent 8. Multiple Allelism _____ requires 2 individuals heterozygous for one gene 9. Dominant _____ requires 2 individuals heterozygous for two genes 10. Incomplete dominance _____ ratio observed in a dihybrid cross _____ ratio observed in a monohybrid cross _____ observed a 1:2:1 phenotypic ratio in a monohybrid cross _____ observed a 1:2:1 genotypic ratio in a monohybrid cross</p><p>PART C: SHORT ANSWER</p><p>1. Describe the difference between incomplete dominance and co-dominance. Provide an example of each. Use only the space provided [Comm – 4 marks]</p><p>Incomplete dominance Co-dominance 2. A man has six fingers on each hand and six toes on each foot. His wife and their daughter have a normal number of digits. Having extra digits is a dominant trait and the man has a heterozygous genotype. What fraction of this couple’s children would be expected to have extra digits? (Show all work for full marks) [TI - 5 marks]</p><p>3. In dogs, barking (B) is dominant to non-barking (b), and pointy ears (E) are dominant to drooping ears (e). What fraction of non-barking, droopy eared pups can you expect from a cross between a female barking, pointy eared dog, whose mother was non-barking and droopy eared, and a male non-barking, droopy eared dog? Be sure to show your phenotypic and genotypic ratios. (Show all work for full marks) [TI – 6 marks]</p><p> a. What percentage of the offspring would display the same phenotype as the mother? ______[TI – 1 mark]</p><p> b. What fraction of the offspring would be appropriate to use in a test cross? ______[TI – 1 mark] 4. Explain how the phenotypic expression of height (a multifactorial trait) demonstrates a continuous distribution. Provide an example of a graph, with possible genotypes, illustrating this type of distribution. [App - 3 marks, Comm – 1 marks]</p><p>5. In sesame plants, the one-pod (T) condition is dominant to the three-pod (t) condition, and normal leaf (N) is dominant to wrinkled leaf (n). A one-pod, normal leaf plant (TTNN) is crossed with a three- pod, wrinkled leaf plant (ttnn). Breeding two of the F1 offspring results in the following F2 generation: 280 one-pod/normal leaf plants, 44 one-pod/wrinkled leaf plants, 49 three-pod/normal leaf plants, and 273 three-pod/wrinkled leaf plants.</p><p>Are the genes for pod type and leaf type located on the same chromosome? Explain. [App - 3 marks]</p><p>6. A, B, C, D and E are genes that are known to be linked. Use the following experimental results to determine the sequence of the genes on the chromosome. [TI – 2 marks, Comm – 1 mark]</p><p>◦ B is at one extreme of the chromosome ◦ D crosses over with A 5% of the time ◦ D crosses over with B 10% of the time ◦ C crosses over with D 15% of the time ◦ E crosses over with C 10% of the time ◦ A crosses over with E 30% of the time ◦ A crosses over with C 20% of the time</p><p>15 </p>