Skills Worksheet Directed Reading B Section: Traits and Inheritance A GREAT IDEA 1. What is the ratio that Mendel found for dominant to recessive traits? a. 1 to 1 c. 3 to 1 b. 2 to 1 d. 4 to 1 2. What do scientists call instructions for an inherited trait? a. alleles c. albinism b. phenotype d. genes 3. What are the two forms of a gene called? a. alleles c. albinism b. phenotype d. genes Phenotype 4. What is a phenotype? a. an inherited problem c. a recessive gene b. a group of 10 alleles d. the way an organism looks 5. What prevents hair, skin, and eyes from having any color? a. alleles c. ratio b. albinism d. probability Genotype 6. What are both inherited alleles together called? Holt Science and Technology 13 Heredity
7. What kind of plant has two dominant genes OR two recessive genes? 8. What kind of plant has one dominant gene AND one recessive gene? Punnett Squares Use the table below to answer questions 9 through 12. For each question, circle the letter of the best answer for each question. P P p p 9. Look at the table above. What is this table called? a. P-grid c. heredity map b. dominance chart d. Punnett square 10. What is a Punnett square used for? a. to show recessive traits c. to show dominant traits b. to show possible offspring d. to show homozygous alleles 11. Look at the table above. If purple flower color (P) is dominant, what color will most of the offspring be? a. purple c. same number of purple and white b. white d. lavender (white and purple mix) 12. Look at the table above. What is the probability that the offspring will be? a. 25% c. 75% b. 50% d. 100% Holt Science and Technology 14 Heredity
More Evidence for Inheritance 13. Which two combinations of genotypes are exactly the same? a. PP and c. pp and b. and pp d. pp and pp WHAT ARE THE CHANCES? Probability 14. What is the chance of a parent with one green allele and one blue allele giving a blue allele to an offspring? a. 100% chance b. 25% chance c. 50% chance d. 75% chance Read the description. Then, draw a line from the dot next to each description to the matching word. 15. the chance that something will happen 16. how probability is usually written 17. how to find probability 18. reason traits in pea plants are easy to predict a. multiply b. only two choices c. fraction or percent d. probability Holt Science and Technology 15 Heredity
MORE ABOUT TRAITS Incomplete Dominance 19. What is it called when each allele has its own degree of influence? a. incomplete dominance b. complete dominance c. cross-breeding d. probability One Gene, Many Traits 20. A white tiger s blue eyes are an example of what? a. first-generation characteristic b. dominant trait c. many genes influencing one trait d. one gene influencing more than one trait Many Genes, One Trait 21. How many genes determine human eye color? a. none b. at least two c. 1,000 d. one The Importance of Environment 22. What can influence traits besides genes? a. height b. albinism c. environment d. phenotype Holt Science and Technology 16 Heredity
TEACHER RESOURCE PAGE 25. half the number of chromosomes that were present in the original cell 26. meiosis 27. genotype 28. sex chromosomes 29. two X chromosomes 30. one X and one Y chromosome 31. the X chromosome 32. the Y chromosome 33. They are more likely to have a sex-linked disorder. 34. Answers will vary. Sample answer: color blindness and hemophilia 35. pedigree 36. carrier 37. recessive 38. selective breeding Directed Reading B SECTION: MENDEL AND HIS PEAS 1. B 2. B 3. D 4. C 5. A 6. C 7. B 8. B 9. C 10. A 11. dominant 12. recessive 13. D 14. B 15. A SECTION: TRAITS AND INHERITANCE 1. C 12. A 2. D 13. B 3. A 14. C 4. D 15. D 5. B 16. C 6. B 17. A 7. C 18. B 8. B 19. A 9. D 20. D 10. B 21. B 11. A 22. C SECTION: MEIOSIS 1. C 2. B 3. A 4. C 5. B 6. B 7. B 8. B 9. D 10. C 11. D 12. B 13. A 14. C 15. B 16. A 17. D 18. meiosis 19. X chromosomes 20. Y chromosome 21. hemophilia 22. pedigree 23. carriers 24. recessive 25. selective breeding Vocabulary and Section Summary SECTION: MENDEL AND HIS PEAS 1. heredity: the passing of genetic traits from parent to offspring 2. dominant trait: the trait observed in the second generation when parents with different traits are bred 3. recessive trait: a trait that reappears in the third generation after disappearing in the second generation when parents with different traits are bred. SECTION: TRAITS AND INHERITANCE 1. gene: one set of instructions for an inherited trait 2. allele: one of the alternative forms of a gene that governs a characteristic, such as hair color 3. phenotype: an organism s appearance or other detectable characteristic 4. genotype: the entire genetic makeup of an organism; also, the combination of genes for one or more specific traits 5. probability: the likelihood that a possible future event will occur in any given instance of the event Holt Science and Technology 92 Heredity