14 Is the following sentence true or false Most traits are controlled by a

14 is the following sentence true or false most

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14. Is the following sentence true or false? Most traits are controlled by a single gene. 15. Label the two graphs to show which one represents a single-gene trait and which one represents a polygenic trait. 100 80 60 40 20 Widow's peak 0 No widow's peak Phenotype Frequency of Phenotype (%) Frequency of Phenotype Phenotype (height) true Did not know how heritable factors wer passed and had no idea how variation appeared genetic variation population gene pool false relative frequency A mutation is a change in a sequence of DNA and can alter the genotype as well as the phenotype of the organism. Mutations occur because of replication of DNA and as a result of radiation adn chemicals in the environment. true true true polygenic Single-gene
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Name______________________________ Class__________________ Date ______________ 58 Section 16–2 Evolution as Genetic Change (pages 397–402) Key Concepts How does natural selection affect single-gene and polygenic traits? What is genetic drift? What is the Hardy-Weinberg principle? Natural Selection on Single-Gene Traits (pages 397–398) 1. Is the following sentence true or false? Natural selection on single-gene traits cannot lead to changes in allele frequencies. 2. If a trait made an organism less likely to survive and reproduce, what would happen to the allele for that trait? 3. If a trait had no effect on an organism’s fitness, what would happen to the allele for that trait? Natural Selection on Polygenic Traits (pages 398–399) 4. List the three ways that natural selection can affect the distributions of phenotypes. a. b. c. Match the type of selection with the situation in which it occurs. Type of Selection 5. Directional 6. Stabilizing 7. Disruptive 8. An increase in the average size of beaks in Galápagos finches is an example of selection. 9. Is the following sentence true or false? The weight of human infants at birth is under the influence of disruptive selection. Situation a. Individuals at the upper and lower ends of the curve have higher fitness than individuals near the middle. b. Individuals at one end of the curve have higher fitness than individuals in the middle or at the other end. c. Individuals near the center of the curve have higher fitness than individuals at either end. 59 10. Draw the missing graph to show how disruptive selection affects beak size.
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