Chapter 5 Study Guide
Transcription
Chapter 5 Study Guide
Chapter 5: Genetics – Study Guide 1. Edited by Foxit Reader Copyright(C) by Foxit Corporation,2005-2010 For Evaluation Only. Name:___________________ Date:______ If a black-furred male gerbil and a white-furred female gerbil mated. All their offspring were black-furred. Why is this? The black fur allele is dominant over the white fur gene. ______________________________________________________________________________________________________ 2. How is anaphase II in meiosis similar to anaphase in mitosis? In both of these steps the chromosomes are pulled apart ______________________________________________________________________________________________________ Gg ________________ 3. In pea plants, the gene for green seeds (G) is dominant over the gene for yellow seeds (g). How is the genotype for the heterozygous condition written? 4. 78 If a dog’s sex cells have 39 chromosomes, how many chromosomes do its body cells have? __________________ 5. 46 How many chromosomes does a human body cell have? _____________ 6. 23 How many chromosomes does a human gamete have? _____________ 7. If two heterozygous purple Fast Plants were crossed, what are the chances that the offspring would have green stems and leaves? (Purple stems are the dominant trait.) To solve this you will need to complete a punnett square between the two parents. Bb and Bb If you do this correctly you should get the answer: 25% 8. A homozygous purple Fast Plant was crossed with a green Fast Plant. What percentage of the offspring would have purple stems? (Purple stems are the dominant trait.) To solve this you will need to complete a punnett square between the two parents. BB and bb You should see that the only possibility is Bb and therfore 100% of the offspring will have purple stems. 9. List two benefits of asexual reproduction It is quick, easy, and requires only one "parent". ________________________________________________________________________________________________________ ________________________________________________________________________________________________________ 10. Although Janele’s blood is normal, her brother Randy has sickle-cell disease. Janele is worried about having a child with the disease. Janele just found out that her husband Terence has one allele for sickle-cell disease. As their genetic counselor, determine Janele and Terences chances of having a child with sickle-cell disease. How would you explain the results of your analysis to the couple? between 0 - 25% Percent chance their child will have sickle-cell disease: __________________ Explanation to the parents: __________________________________________________________________ If Janele is a carrier then her child will have a 25% chance of getting Sickle Cell. ________________________________________________________________________________________________________ ________________________________________________________________________________________________________ If Janele is not a carrier then her child will have a 0% chance of getting Sickle Cell. ______________________________________________________________________________________________________ Edited by Foxit Reader Copyright(C) by Foxit Corporation,2005-2010 For Evaluation Only. The genotypes of two cats are shown below: Dominant Alleles: solid color fur (F), short fur (L), short ears (E), and short tail (T) Recessive Alleles: patches on fur (f), long fur (l), long ears (e), and long tail (t) Genotype Phenotype Genotype Phenotype Fur pattern Ff solid Ff solid fur Fur length ll long fur Ll short fur Ear length ee long ears ee long ears Tail length TT Short tail Tt short tail 11. Complete the Punnett squares and predict the expected ratios of phenotypes in the offspring for each trait. F f F FF Ff f Ff ff e e e ee ee e ee ee Fur Pattern Ratio of solid to patches 1 3 : ___ ___ Ear length Ratio of short to long 4 0 : ___ ___ l l L Ll Ll l ll ll Fur length Ratio of short to long 2 2 ___ : ___ T t T TT Tt T TT Tt Tail length Ratio of long to short 0 4 ___ : ___ Consider if these two cats mate: circle any traits would be impossible for the offspring to get. Fur Pattern Fur Length Ear length Tail length Solid Long Long Long Patches Short Short Short 12. Green (G) is the dominant color for pods in pea plants. Yellow (g) is recessive. Is it possible to have a heterozygous yellow pod? Explain. Gg will produce a geen pea pod. It can never be yellow because the allele for green ___________________________________________________________________________________________ is dominant. ___________________________________________________________________________________________ ___________________________________________________________________________________________ 13. Explain how you could determine whether the seeds in a packet of round pea seeds have the genotype RR or Rr, in which R represents round seeds and r represents wrinkled seeds. This will not be on the test. ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 14. Why can’t a male be a carrier of color blindness? Edited by Foxit Reader Copyright(C) by Foxit Corporation,2005-2010 For Evaluation Only. Males only have one X chromosome so they only have one opportunity to get the correct ___________________________________________________________________________________________ gene so they either have the trait or they do not. ___________________________________________________________________________________________ ___________________________________________________________________________________________ 15. Predict how Mendel’s results would have differed if he had not controlled the breeding of plants in his experiments. Mendel would not have been able to tell the difference between GG homozygous and ___________________________________________________________________________________________ Gg heterozygous. ___________________________________________________________________________________________ ___________________________________________________________________________________________ 16. When gametes join to form a new organism how does that zygote return to the diploid number Have of the chromosomes come from mom and the other half from dad. ___________________________________________________________________________________________ When they are added together the zygote then has the full set. ___________________________________________________________________________________________ In humans: 23 + 23 = 46 46 is a full set. ___________________________________________________________________________________________ 17. Describe the relationship between genes and chromosomes. Chromosomes are made from many genes put together in the same way a bracelet ___________________________________________________________________________________________ ___________________________________________________________________________________________ can be made of many beads put together. 18. Mammals, including humans, reproduce sexually. Explain the genetic benefits of sexual reproduction. Include the term genetic variation in your response. ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 19. Why do sexually reproducing organisms always have an even number of chromosomes in their body cells? ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 20. Two students are discussing the studying of heredity: Decide which of the two students you agree with and explain why. Kate says that Heredity has shown us that the traits expressed in the offspring are exactly half from the mother and half from the father. Brett disagrees with Kate and states that only half of each parent’s chromosomes are passed on to the offspring. Brett is correct. We get an equal number of chromosomes and genes from each of our parents ________________________________________________________________________________________________________ However, we don't necessarily get an equal number of traits from our parents. ________________________________________________________________________________________________________ ______________________________________________________________________________________________________ This would be easier for me to show with a picture. 21. Luther Burbank, a California plant breeder, grafted branches from many kinds of fruit - pears, plums, peaches, and different varieties of apples - onto one apple tree. If seeds produced by one of the apple blossoms germinated and grew into a tree, how many kinds of fruit would you expect to find on the new tree and why? The seed from the apple would only produce an apple tree. That tree would not have any ________________________________________________________________________________________________________ of the other fruits because the DNA in the apple seed was not changed. ________________________________________________________________________________________________________ ______________________________________________________________________________________________________ 22. Protein synthesis