Reproduction and genetic variation

9.What does a polymorphic gene mean?

10.In RNA viruses, what is a major source of genetic variation?

11.A scientist observes that a population of flowers has red, pink, and white petals. This is an example of:

12.Which of the following contributes to genetic variation during sexual reproduction?

13.A population of beetles has two alleles for body color: green (G) and brown (g). The frequency of the green allele is 0.6. Assuming Hardy-Weinberg equilibrium, what is the expected frequency of heterozygous beetles?

14.In a certain plant, the allele for tall stems (T) is dominant over short stems (t). A cross between two heterozygous tall plants produces 120 offspring. How many of these offspring are expected to be short?

15.A scientist measures the frequency of a recessive allele in a population over several generations and observes that it decreases from 0.5 to 0.2. Which of the following is the most likely explanation?

16.Which of the following is an example of a discrete trait that shows genetic variation?

17.A farmer grows potatoes by planting pieces of a single parent potato. All the new plants are genetically identical. This is an example of which type of reproduction?

18.The graph below shows the frequency of two alleles (A and a) in a population over 50 generations. Which of the following best explains the pattern observed?

19.In a population of flowers, the allele for red petals (R) is dominant over white petals (r). If the frequency of the white allele is 0.3, what is the expected frequency of red-flowered plants assuming Hardy-Weinberg equilibrium?

20.A scientist compares the DNA sequences of two populations of the same species and finds many differences in the noncoding intron regions. What does this indicate?

21.Which of the following is the ultimate source of all genetic variation?

22.The diagram shows a Punnett square for a cross between two pea plants. If the trait is seed shape (R = round, r = wrinkled), what percentage of offspring will be wrinkled?

23.Which process during meiosis increases genetic variation by exchanging DNA between homologous chromosomes?

24.A population of birds has two alleles for beak size: large (L) and small (l). The frequency of the large allele is 0.8. What is the frequency of the small allele?

25.A student wants to investigate whether a population of fruit flies shows genetic variation for wing length. Which of the following is the best method to detect variation at the DNA level?

26.A scientist uses protein electrophoresis to study genetic variation in a population of beetles. She finds that 40% of the genes examined have two or more alleles. What does this result indicate?

27.In an experiment, a researcher compares the DNA sequences of a gene from two populations of the same species that live in different regions. She finds many differences in the noncoding intron regions but few in the coding exons. What is the most likely explanation?

28.A population of flowers has three petal colors: red, pink, and white. The allele for red (R) is dominant over white (r), and heterozygotes (Rr) are pink. If a student counts 100 red, 200 pink, and 100 white flowers, what is the frequency of the white allele (r) in the population?

29.Which of the following is an example of a quantitative trait that shows continuous variation?

30.A farmer grows potatoes by cutting a single potato into pieces and planting each piece. What type of reproduction does this represent?

31.In a genetics lab, a student crosses two heterozygous pea plants (Bb × Bb) for seed color where B = yellow dominant and b = green recessive. The student observes 150 offspring: 112 yellow and 38 green. What is the most likely explanation for the deviation from the expected 3:1 ratio?

32.A researcher studying RNA viruses observes that a single host cell is infected with two different strains of the same virus. Some new virus particles have a combination of genes from both strains. What process most likely generated these new viruses?

33.Which of the following best explains why most mutations are neutral or harmful rather than beneficial?

34.The diagram shows a Punnett square for a cross between two pea plants. If the trait is seed shape (R = round, r = wrinkled), what percentage of offspring will be homozygous recessive?

35.A student uses a technique called gel electrophoresis to compare DNA samples from four different plants. The resulting banding pattern shows that each plant has a unique pattern. What does this indicate?

36.In a population of butterflies, a recessive allele for white wings (w) has a frequency of 0.1. Assuming Hardy-Weinberg equilibrium, what is the expected frequency of heterozygous individuals?

37.Which type of reproduction produces offspring that are genetically identical to the parent?

38.What is the ultimate source of all genetic variation?

39.In a monohybrid cross between two heterozygous parents (Bb × Bb), what is the expected phenotypic ratio of dominant to recessive traits?

40.A student measures the leg lengths of 50 dogs of the same breed. The lengths range from 30 cm to 45 cm, with most dogs having a leg length around 37 cm. This variation in leg length is best described as: