1 Four nucleic acid samples are analyzed to determine the pe

1. Four nucleic acid samples are analyzed to determine the percentages of the nucleotides they contain. Survey the data in the table below, and for each of the four samples, state whether it is DNA or RNA and whether it is single-stranded or double-stranded. State your reasoning in one or two sentences.

A C G T U Sample 1 17% 24% 28% 0% 31% Sample 2 21% 29% 29% 21% 0% Sample 3 27% 27% 23% 23% 0% Sample 4 32% 18% 32% 0% 18%

2. In the datura plant, purple flower color is controlled by a dominant allele P. White flowers are found in plants homozygous for the recessive allele p. A purple-flowered plant is fertilized by pollen from an unknown individual, and its progeny are 57 purple-flowered plants and 19 white-flowered plants.

a. What is the genotype of the original purple-flowered plant?

b. If the 57 purple-flowered progeny are self-fertilized, about how many of these 54 individuals do you expect to breed true (have only purple-flowered offspring)?

3. Black skin color is dominant to pink skin color in pigs. Two heterozygous black pigs are crossed.

a. What is the probability that the first two piglets both have pink skin?

b. What is the probability that if three piglets are produced, two will be pink and one will be black?

4. Organisms with the genotypes aaBbCcDd and AaBbCcDd are crossed. What are the expected proportions of the following progeny?

a. A–B–C–D– b. AabbCcDd c. A phenotype identical to either parent d. A–B–ccdd

Solution

1. Sample 1 is ssRNA

Sample 2 is dsDNA

Sample 3 is ssDNA

Sample 4 is ssRNA

2. a. The genotype of the original purple-flowered plant is Pp.

b. 27 individuals will be true breed for purple colour.