Download Apex reading guide chp 4.2.7 practice Gene expression

APEX 4.2.7 Practice: Genetics and gene expression
Points possible: 25
Name ____________________
Date: ____________
1. A woman buys seeds for an annual flowering plant. After planting the seeds in her garden, she is
happy to see that all of them produce red flowers. She collects the seeds produced by the flowers at the
end of the season and stores them over the winter. When she plants them the next spring, she is
surprised to find that 8 plants produced white flowers and 32 plants produced red flowers. Explain this
outcome by comparing the observed numbers of white and red flowering plants to those expected if the
following conditions are assumed:


The plants are self-pollinating (that is, seeds are only produced by crosses between plants in the
garden).
The flower color trait results from two alleles, one dominant and the other recessive.
(3 points)
2. A human needs at least one functional allele for a particular protein in order to have normal
metabolic behavior. A man and a woman marry and produce 8 children. Neither parent has the
metabolic disorder related to the protein described above, but 3 of their children do. Explain the most
likely pattern of inheritance, based on the data below. (3 points)
Family Member
Father
Mother
Daughter 1
Daughter2
Son 1
Son 2
Son 3
Son 4
Son 5
Son 6
Normal metabolism
Metabolic disorder
✓
✓
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3. The following table shows the results of a breeding experiment to study the inheritance of flower
color and grain length in plants, two genes that exhibit complete dominance in phenotypes. Truebreeding parent plants with purple flowers and long pollen grains were crossed with true-breeding
parent plants with red flowers and short pollen grains. A second experiment was also conducted
between members of the F1 generation to produce an F2 generation. The phenotypes of the resulting
offspring in the F1 and F2 generations are in the figure below.
a. Using the data in the table, identify the dominant alleles for flower color and grain length. Explain
your response. (3 points)
b. Analyze the distribution of phenotypes in the F2 generation. Explain whether the observed results
match those expected based upon the results of the first cross. (3 points)
4. In fruit flies, three genes are all located on the same chromosome. These genes code for body color,
eye color, and wing size — in that order — along the chromosome. The alleles that give rise to a
yellow body (y), white eyes (w), and miniature wings (m) are all recessive traits. Gray body color (Y),
red eye color (W), and normal wing size (M) are dominant.
Draw a sketch of the chromosome containing these three genes. Use the data from two-factor crosses
between the homozygous parents shown below to roughly sketch the relative distances between the
genes. (3 points)
5. A study was conducted to examine the influence of vitamin A on gene expression in developing fish
larvae. Fish larvae were divided into control and experimental groups. The control group received a
complete diet; the experimental group received a complete diet minus vitamin A. Larvae from the
experimental group did not demonstrate the same pattern of gene expression at different stages during
development that was observed in larvae from the control group. At the end of the study, experimental
larvae showed signs of skeletal deformities that were not observed in the control group.
a. Explain the relationship between vitamin A and normal development. (2 points)
b. Describe how the process of gene expression can affect the development of specialized structures
such as bones. (2 points)
6. Researchers studied the effects of atrazine, a herbicide, on developing frog larvae. They found that
administration of atrazine did not affect the frog’s life span or its overall health. Atrazine also had no
observable effect on female frog larvae. However, atrazine did convert the male larvae into
hermaphrodites — organisms with both male and female sex organs — capable of producing viable
eggs.
a. Describe how gene expression differs during the normal process of sexual differentiation in animals.
(2 points)
b. Explain a possible mechanism for atrazine's effect on developing male frogs. (2 points)
7. Explain how regulation of gene expression allows a cell to efficiently use its energy supply to carry
out specific metabolic reactions that are necessary at specific times. (2 points)