Bio Final

In a particular variety of corn, kernel color is controlled by a single gene with two alleles. The dominant allele results in purple kernels, and the recessive allele results in yellow kernels. A single corncob may contain hundreds of individual kernels, each of which is the result of a separate fertilization event. Predict the frequency of yellow kernels that result from a cross between two heterozygous plants.

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Male chickens carry two Z sex chromosomes, while female chickens carry only one Z sex chromosome and one W sex chromosome. Located on the Z chromosome is a gene for barring. Barred feathers have black and white stripes. The barred trait is dominated to the unbarred trait. Chickens have a fleshy growth on the top of the head called a comb. An autosomal train called rose comb is dominant to a trait called single comb. An unbarred male heterozygous for the rose-comb trait is crossed with a barred female with a single comb. What proportion of the progeny are expected to be barred males with single combs?

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Cancer can result from a variety of different mutational events. Which of the following is least likely to result in the initiation of a cancerous tumor?

A defect in the cell-cycle checkpoint prevents a cell from entering the S phase.

Based on the model, which of the following describes the most likely mechanism by which CDK5 regulates neurotransmitter release?

CDK5 alters the activity of other proteins involved in the movement of synaptic vesicles to the plasma membrane.

If the chemical signals in the cytoplasm control the progression of a cell to the M phase of the cell cycle, then fusion of a cell in G1 with a cell in early M phase would most likely result in what?

Condensation of chromatin in preparation for nuclear division in both cells.

Previous experiments indicate that CDK5 is active only when attached to a protein called p35. Which of the following best predicts how p35 might play a role in regulating neuron function

Degradation of p35 results in increased synaptic activity.

Which of the following best describes the role of mitosis in the cell cycle?

Distributing replicated chromosomes to daughter nuclei.

The process depicted in the image of paired homologous chromosomes with the centromeres linked is best summarized by which of the following description?

During meiosis, crossing over leads to recombination of alleles between homologous chromosomes.

Based on the model, which of the following best explains why a bright green fluorescence was observed following stimulation of a presynaptic neuron?

GFP* contained in synaptic vesicles moved into the synaptic cleft by exocytosis.

A micro electrode is inserted into a neuron. A voltage recorder then measures the voltage difference between the microelectrode inside of a cell and an electrode placed outside the cell. Which of the following plots most accurately represents the changes in membrane potential throughout a single action potential?

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Information is transmitted through the nervous system when one neuron signals another neuron. The structure of neurons enables transmission to proceed quickly . Which does the following diagrams correctly identifies both the structure and information flow of neurons?

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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 typically show no symptoms of the disorder. Which of the following pedigrees most accurately represents a family with a history of Tay-Sachs disease?

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The transmission of an action potential across a synapse involves the release of neurotransmitters by the presynaptic neuron. The arrival of the action potential triggers the rise in the calcium concentration in the synaptic terminal, and the change in concentration triggers a release of neurotransmitters into the synaptic cleft. Which of the following representations of the movement of Calcium, Sodium, and Potassium ions best shows how an action potential is transmitted to the postsynaptic neuron?

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Which of the following best represents two different signaling pathways that share a second messenger?

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Within a forest ecosystem, there is a large amount of diversity among members of a warbler species. Of the following stages of meiosis, which contributes most to diversity among the warblers?

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Which of the following best supports the hypothesis that CDK5 negatively regulates neurotransmitter release?

Inhibition of CDK5 activity in neurons increases the movement of synaptic vesicles to the plasma membrane in response to a specific stimulus.

A researcher examining a root tip observes a plant cell with condensed sister chromaticism kinetochores with attached microtubules, and individual chromosomes that are aligned at the equatorial plate of the cell. Which of the following best describes the next process in the cell?

Paired chromatids will separate, and the new daughter chromosomes will move towards opposite poles of the cell.

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.

Steroid hormones, such as testosterone, pass through the plasma membrane and bind to an intracellular protein, as shown in the diagram below. The hormone-receptor complex then enters the nucleus, where it interacts with DNA to promote transcription of a specific gene.

Production of a specific mRNA will increase as a result of the binding of the hormone-receptor complex to DNA.

Eye pigment in a particular strain of fly is determined by two genes. An autosomal gene that controls the color of the pigments in the eye has two alleles: a dominant allele (R) that results in red eyes and a recessive allele (r) that results in sepia eyes. A sex-linked gene that controls the expression of the colored pigments also has two alleles: a dominant allele (T) that allows for expression of the colored pigments and a recessive allele (t) that does not allow for expression of the colored pigments. Individuals without a T allele have white eyes regardless of the alleles of other eye-color genes. Which of the following represents a cross between a white-eyed female and a red-eyed male?

Rr X(t)X(t) x Rr X(t)Y

The data above represent the result of three different crosses involving inheritance of a gene that determines whether a certain organism is blue or white. Which of the following best explains the mechanism of inheritance of the gene?

The allele for blue is an X-linked dominant allele because there are no blue male offspring in cross 2.

Based on the model of eukaryotic cell cycle regulation shown in the figure, which of the following best describes the effect of a drug that blocks the production of cyclin?

The cell would be prevented from entering mitosis and stop dividing.

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 F1 offspring are all red-eyed. The F1 flies are allowed to interbreed, producing the following F2 population: Females: 40 red, 13 sepia Males: 39 red, 11 sepia. Which 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.

In Drosophila melanogaster the allele for wild-type tan body color (B) is dominant to the recessive allele for black body color (b). Similarly, the allele for wild-type wing shape (V) is dominant to the recessive allele for vestigial wing phenotype (v). In the cross BBVv x bbvv, the expected and observed results are shown. Which of the following best explains the observed results of the cross?

The genes for body color and wing shape are located close to each other on the same chromosome.

Which of the following statements best describes how a growth factor stimulates cell division outside a cell?

The growth factor binds to receptors on the cell surface, initiating a signal transduction pathway that activates specific target genes.

The pedigree suggests that the gene is on a nuclear chromosome, and not on mitochondrial DNA because?

maternal mitochondrial mutations are inherited by all of a mother's offspring.