REVIEW Chapter 6 - McGraw-Hill Ryerson

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$Math and Chemistry - McGraw-Hill Ryerson$

Practice Problems 1. If a man has type AB blood and a woman has type A blood, what possible blood types could their children have? 2. A baby has blood type AB. If the baby’s mother has blood type B, what blood type(s) could the father have? 3. A couple just brought home their new baby from the hospital. Th ey begin to suspect that the hospital switched babies, and the baby they brought home is not theirs. Th ey check the hospital records, and fi nd that the man’s blood type is B, the woman’s blood type is AB, and the baby’s blood type is O. Explain why the parents are or are not justifi ed in their concern about this baby. 4. Four children have the following blood types: A, B, AB, and O. Could these children have the same two biological parents? Explain. 5. Some of the off spring of a chinchilla rabbit and a Himalayan rabbit are albino. What are the genotypes of the parents? 6. A chinchilla rabbit with genotype cchch is crossed with a Himalayan rabbit with genotype chc. What is the expected ratio of phenotypes among the off spring of this cross? 7. Could a mating between a chinchilla rabbit and an albino rabbit produce a Himalayan rabbit? Explain your reasoning. Your answer should include reference to the genotypes and phenotypes of the parents and the off spring. Environmental Effects on Complex Patterns of Inheritance Environmental conditions oft en aff ect the expression of traits. For example, some genes are infl uenced by temperature. Th e dark colour in Himalayan rabbits, shown in Figure 6.8, is on the cooler parts of their bodies: the face, ears, tails, and feet. In these animals, dark colouring is the result of a gene that is only active below a certain temperature. One way to study the eff ect of the environment on expression of traits is to study genetically identical organisms placed in diff erent surroundings. For example, identical twins are genetically identical. Diff erences in the activity of their genes can be due to environmental eff ects. Figure 6.8 The dark ears, nose, feet, and tails of Himalayan rabbits are thought to be caused by lower body temperature in these areas. 8. In one family, all three siblings have type B blood. a. Use Punnett squares to show how two diff erent sets of parent genotypes could produce this result. b. Which of the two sets of potential parents in your answer to (a) is more likely to be the parents of these siblings? Explain why. 9. In dogs, coat colour is determined by the interaction between three alleles. Th e allele AS produces a dark coloured dog, a y produces a sandy coloured dog, and at produces a spotted dog. Th e order of dominance is AS > a y > at . Determine the following from the pedigree below. a. the genotypes of the parents (I-1 and I-2) b. the probability of an off spring from the mating between individuals II-2 and II-3 having spots c. the possible genotypes of individual II-1 I II 1 1 2 2 3 Key dark coloured sandy coloured spotted 10. A dark coloured dog is mated with a sandy coloured dog. Th e litter of puppies includes a dark puppy, a sandy puppy, and a spotted puppy. Use a Punnett square to determine the possible genotypes of the off spring and the parents. Note: Use the information about dog coat colour inheritance from question 9 to answer this question. SuggestedInvestigation Plan Your Own Investigation 6-A, Environmental Influences on the Production of Chlorophyll <strong>Chapter</strong> 6 Complex Patterns of Inheritance • MHR 247
continuous variation a range of variation in one trait resulting from the activity of many genes polygenic trait a trait that is controlled by more than one gene Polygenic Inheritance Mendel carefully selected plants that had very diff erent heights so there would be no question about phenotypes. However, there are traits that exhibit continuous variation. Th ese are traits for which the phenotypes vary gradually from one extreme to another. Some examples of traits that show continuous variation include height and skin colour in humans, ear length in corn, and kernel colour in wheat. Continuous traits cannot be placed into discrete categories because they vary over a continuum. For example, height in humans varies over a wide range of values. People cannot be categorized as only short or tall. Traits that exhibit continuous variation are usually controlled by more than one gene. For some traits this can involve several genes. Traits that are controlled by many genes are called polygenic traits. A group of genes that all contribute to the same trait is called a polygene. Each dominant allele contributes to the trait. Recessive alleles do not contribute to the trait. For skin colour, the more dominant alleles a person has, the darker their skin. Th e graph in Figure 6.9 shows that there are more intermediate phenotypes than extreme phenotypes. Frequency Skin Colour AaBbcc AaBbCc aaBbCC aaBBCC AabbCc AAbbCc AAbbCC aaBbCc AabbCC AABBcc Aabbcc AAbbcc AABbcc AaBbCC AaBBCC aaBbcc aaBBcc aaBBCc AaBBCc AABbCC aabbcc aabbCc aabbCC AaBBcc AABbCc AABBCc AABBCC 0 1 2 3 4 5 6 Number of Dominant Alleles Figure 6.9 This graph shows possible shades of skin colour from three of the sets of alleles that determine this trait. Predict the effect of more gene pairs on the possible phenotypes. Activity 6.1 Identifying a Polygenic Trait A polygenic trait is one that is controlled by more than one gene and shows continuous variation. In this activity, you will choose one human trait that you hypothesize is controlled by more than one gene and shows continuous variation. You will then collect data from your classmates to test your hypothesis. Materials • ruler or measuring tape (if necessary) • graph paper Procedure 1. In your group, choose one human trait that you think is polygenic. Make sure your choice is one for which data can be easily and respectfully collected from your classmates. 248 MHR • Unit 2 Genetic Processes 2. Construct a data table to organize your data. Keep in mind that you will be measuring a particular trait and recording the number of times that measurement of the trait occurs. 3. Collect your data from your classmates. 4. Create a line graph of your data. Your graph should refl ect the actual measurements you took and the frequency of the values that you measured. Questions 1. Do your data support your hypothesis that the trait you selected is polygenic? Explain. 2. How could this activity be improved to provide a clearer picture of the inheritance pattern of the trait you selected?
Page 1 and 2: CHAPTER 6 Specifi c Expectations In
Page 3 and 4: Key Terms SECTION 6.1 incomplete do
Page 5 and 6: heterozygous advantage a survival b
Page 7: Figure 6.7 There are seven differen
Page 11 and 12: Section 6.1 REVIEW Section Summary
Page 13 and 14: Figure 6.11 In most of the gametes
Page 15 and 16: SuggestedInvestigation ThoughtLab I
Page 17 and 18: Figure 6.15 Great Britain’s Queen
Page 19 and 20: Practice Problems 11. A woman who i
Page 21 and 22: Key Terms SECTION 6.3 bioinformatic
Page 23 and 24: ioinformatics a field of study that
Page 25 and 26: 264 MHR • Unit 2 Genetic Processe
Page 27 and 28: genetic profile the complete genoty
Page 29 and 30: Plan Your Own INVESTIGATION Skill C
Page 31 and 32: ThoughtLab INVESTIGATION Materials
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Page 37 and 38: Chapter 6 SELF-ASSESSMENT Select th
Page 39 and 40: Unit 2 Project An Issue to Analyze
Page 41 and 42: UNIT 2 Chapter 5 Chapter 6 SUMMARY
Page 43 and 44: UNIT 2 REVIEW 8. What is a key indi
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REVIEW Chapter 6 - McGraw-Hill Ryerson

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