Bio Study Guide
Eye color in a particular strain of fly is influenced by one gene with two alleles: a dominant allele that results in red eyes and a recessive allele that results in sepia eyes.A red-eyed female from a true-breeding population is mated with a sepia-eyed male. The F 1 offspring are all red-eyed. The F 1 flies are allowed to interbreed, producing the following in the F 2 generation.Females: 40 red eyes; 13 sepia eyesMales: 39 red eyes; 11 sepia eyesWhich of the following best describes the likely mode of inheritance for the eye-color gene?
The eye-color gene is likely autosomal because males and females have similar phenotype ratios.
Which diagram best illustrates the processes of DNA replication, meiosis, and separation of sister chromatids?
The picture with that produces four cells at the end.
In fruit flies, the allele for vestigial wings is recessive to the allele for for wild-type wings, and the allele for white eyes is recessive to the allele for red eyes. The gene controlling wing type is carried on an autosome whereas the gene controlling eye color is carried on the X chromosome.A true-breeding female with the wild type wings and white eyes is crossed with a male with vestigial wings and red eyes. What proportion of the offspring are expected to be males with wild-type wings and white eyes? Give your answer a decimal value to the nearest hundredth.
0.5
An allele on the X chromosome is responsible for the recessive trait of red-green color blindness in humans. The daughter of a woman who is color-blind has normal vision and marries a man who is color-blind. This couple has a son, what is the probability that the son will be color-blind?
1/2
A certain species of plant has four unlinked genetic loci, W, X, Y, and Z. Each genetic locus has one dominant allele and one recessive allele. For a plant with the genotype WwXxYyZz, what is the probability that the plant will produce a gamete with a haploid genotype of Wxyz?
1/4
The processes illustrated in the models depicted above all result in which of the following?
An increase in genetic variation
The process depicted in the image above is best summarized by which of the following descriptions?
During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.
A genetic marker is a gene (DNA sequence) with a known location and a somewhat predictable inheritance pattern. The inheritance of a genetic condition located on the Y sex chromosome is indicated by "Y" on the pedigree below. Because the condition results from a unique sequence of nucleotides that is extremely rare in the human population, it is often used in paternity cases to determine if offspring are related to the potential parents.
Markers on other chromosomes in the body would be less useful for determining paternity, because during meiosis there is only a 50% chance that they will be passed on to a child, but the Y chromosome will be passed on to all male offspring.
A student in a biology class crossed a male Drosophila melanogaster having a gray body and long wings with a female D. melanogaster having a black body and apterous wings. The following distribution of traits was observed in the offspring.
NOT The alleles for gray body and long wings are dominant.
A blue-flowered African violet of unknown ancestry self-pollinated and produced 50 seeds. These seeds germinate and grow into flowering plants. Of these plants, 36 produce blue flowers and 14 produce pink flowers. What is the best explanation for the pink-flowered offspring?
Pink flower color is a trait recessive to blue flower color.
Tay-Sachs disease is a rare inherited disorder caused by an autosomal recessive allele of the HEXA gene. Affected individuals exhibit severe neurological symptoms and do not survive to reproductive age. Individuals who inherit one copy of the allele (Tay-Sachs carriers) typically show no symptoms of the disorder. The frequencies of Tay-Sachs carriers in the general population of North America and in three different subpopulations are presented in the table. Based on the information presented, which of the following best explains the difference in phenotype between Tay-Sachs carriers and homozygous recessive individuals?
Tay-Sachs carriers synthesize an essential enzyme that homozygous recessive individuals cannot synthesize.
The diagram below shows the meiotic divisions involved in the formation of an egg cell (oogenesis). The polar bodies produced during oogenesis eventually degenerate.
The first polar body is produced in meiosis I, when the pairs of homologous chromosomes are separated into two cells. In meiosis II, the second polar body is generated when sister chromatids are separated into two cells to obtain the haploid number of chromosomes in the egg.
Tay-Sachs disease is a rare inherited disorder caused by an autosomal recessive allele of the HEXA gene. Affected individuals exhibit severe neurological symptoms and do not survive to reproductive age. Individuals who inherit one copy of the allele (Tay-Sachs carriers) typically show no symptoms of the disorder. Which of the following pedigrees most accurately represents a family with a history of Tay-Sachs disease?
The one where the entire second generation is affected.
