campbell ch 11 and 12 AP Bio

The concentration of all gibberellins 65 days after planting is approximately

20 ng/gram

Which of the following is LEAST likely to result in the initiation of a cancerous tumor?

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

Which of the following best describes a drug interaction that directly interferes with a signal transduction pathway?

A medication enters the target cell and inhibits an enzyme that normally synthesizes a second messenger.

The figure above shows a model of a ligand precursor being cleaved to produce an active ligand that binds to a specific receptor. Which of the following is most likely to reduce the binding of the active ligand to its receptor?

A mutation in the receptor gene that causes a substitution of a charged amino acid for a nonpolar amino acid in the ligand binding site of the receptor

Which of the following is (are) true of ligand-gated ion channels?

A, B, and C are true.

The cell cycle of yeast cells grown in the nutrient-poor environment is approximately what percent of the cell cycle of yeast cells grown in the nutrient-rich environment?

A.) 168

Glycogen synthetase kinase 3 beta is a protein kinase that has been implicated in many types of cancer. Depending on the cell type, the gene for glycogen synthetase kinase 3 beta (GSK3β) can act either as an oncogene or as a tumor suppressor. Which of the following best predicts how GSK3β mutations can lead to the development of cancer?

A.) Cells with inactive GSK3β fail to trigger apoptosis.

Air is less dense at very high elevations, so less oxygen is available than in the denser air at sea level. Based on the model in Figure 1, if a person travels from sea level to a high elevation location, which of the following correctly predicts the response to the decreased blood oxygen level?

B.) More erythropoietin will be secreted from the kidneys, increasing production of erythrocytes.

Figure 1 shows the number of chromosomes observed in an actively dividing human cell at each stage of cell division. Which of the following presents a correct interpretation of the changes in chromosome number depicted in Figure 1?

C.) Chromosomes enter metaphase containing two chromatids attached by a centromere. During anaphase, the chromatids are separated, each becoming a chromosome. Cytokinesis distributes the chromosomes into two separate cells.

Researchers performed an experiment to determine the effect of certain genetic mutations on mitosis in tropical fruit fly embryos. They determined the percentage of cells in each of four phases of mitosis as shown in Figure 1. Which of the following patterns is shown by the data?

C.) In mutant 3 cells, more time is spent in prophase/prometaphase than in the later stages of mitosis.

The epinephrine signaling pathway plays a role in regulating glucose homeostasis in muscle cells. The signaling pathway is activated by the binding of epinephrine to the beta-2 adrenergic receptor.

C.) Phosphorylase kinase will remain active because protein kinase A will no longer be deactivated.

What is the expected percent change in the DNA content of a typical eukaryotic cell as it progresses through the cell cycle from the start of the G1 phase to the end of the G2 phase?

D.) +100%

Based on Figure 1, what percent of the time required to complete a full cycle do the cells typically spend in interphase?

D.) 95%

Cancer cells behave differently than normal body cells. For example, they ignore signals that tell them to stop dividing.Which of the following conditions will most likely cause a normal body cell to become a cancer cell?

D.) The environment contains mutagens that induce mutations that affect cell-cycle regulator proteins.

Based on Figure 1, which of the following describes the role of cyclin in the regulation of the cell cycle?

During M phase, the cyclin level peaks, resulting in an increased binding frequency with CDK

Which of the following are primarily responsible for cytokinesis in plant cells?

Golgi-derived vesicles

Many human cells can be stimulated to divide by hormonelike growth factors that bind to receptor proteins (R) on the plasma membrane and trigger an internal signal-transduction cascade.

Growth-factor signaling can trigger mitosis in cells that are in direct contact with other cells.

A researcher is conducting an experiment in which cells in different phases of the cell cycle are fused together. The researcher then records what happens to the nuclei of the resulting cell

How do chemical messengers affect a cell's transition between the phases of the cell cycle?

Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?

MPF

Which of the following is the best explanation for the fact that most transduction pathways have multiple steps?

Multiple steps provide for greater possible amplification of a signal.

Type I diabetes results from the destruction of insulin-producing cells in the pancreas. Individuals with type I diabetes produce insufficient amounts of insulin, a hormone that regulates the concentration of glucose in the blood.

The drug will have little or no effect on the signaling pathway because the receptors will not be activated in the absence of insulin.

Researchers studying cell cycle regulation in budding yeast have observed that a mutation in the CDC15 gene causes cell cycle arrest in telophase when the yeast cells are incubated at an elevated temperature. Which of the following statements best predicts the effect of the cell cycle arrest on proliferating yeast cells?

The yeast cells will replicate their chromosomes but will fail to complete cytokinesis.

Regarding mitosis and cytokinesis, one difference between higher plants and animals is that in plants, sister chromatids are identical, but they differ from one another in animals.

a cell plate begins to form at telophase, whereas in animals a cleavage furrow is initiated at that stage.

Which of the following is a correct conclusion that can be drawn from data in figures 1, 2, and 3?

an increase in GA1 levels occurs a day or two before the seedlings start to grow rapidly

The centromere is a region in which new spindle microtubules from at either end.

chromatids remain attached to one another until anaphase.

If 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 the-

condensation of chromatin in preparation of nuclear division in both cells

One difference between cancer cells and normal cells is that cancer cells

continue to divide even when they are tightly packed together.

Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?

cyclin

Of the following, a receptor protein in a membrane that recognizes a chemical signal in most similar tothe active site of an allosteric enzyme in the cytoplasm that binds to a specific substrate.a particular metabolic pathway operating within a specific organelle.

the active site of an allosteric enzyme in the cytoplasm that binds to a specific substrate.

Which of the following is a correct conclusion that can be drawn based only on the data in Figure 4

the greater the inhibition of GA1 synthesis, the lower the plant height after 80 days

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

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

Which of the following best explains the most likely method by which this antitumor drug works?

trabectedin increases the production of cyclin proteins that signal the cell to enter prophase