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Biology for AP® Courses

Critical Thinking Questions

Biology for AP® CoursesCritical Thinking Questions
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20 .
What is the difference between intracellular signaling and intercellular signaling?
  1. Intracellular signaling occurs between cells of two different species. Intercellular signaling occurs between two cells of the same species.
  2. Intracellular signaling occurs between two cells of same species. Intercellular signaling occurs between cells of two different species.
  3. Intracellular signaling occurs within a cell. Intercellular signaling occurs between cells.
  4. Intracellular signaling occurs between cells. Intercellular signaling occurs within cell.
21 .
Refer to Figure 9.4
.
Review the activity involved in a signaling molecule binding to an internal receptor, as depicted in the illustration. Identify the best description of the differences between internal receptors and cell-surface receptors.
  1. Internal receptors bind to ligands that are hydrophobic and the ligand-receptor complex directly enters the nucleus, initiating transcription and translation. Cell- surface receptors bind to hydrophilic ligands and initiate a signaling cascade that indirectly influences the making of a functional protein.
  2. Internal receptors bind to ligands that are hydrophilic and the ligand-receptor complex directly enters the nucleus, initiating transcription and translation. Cell-surface receptors bind to hydrophobic ligands and initiate a signaling cascade that indirectly influences the making of a functional protein.
  3. Internal receptors bind to ligands that are hydrophobic and initiate the signaling cascade that indirectly influences the making of a functional protein. Cell-surface receptors bind to hydrophilic ligands and a ligand-receptor complex directly enters the nucleus, initiating transcription and translation.
  4. Internal receptors are integral membrane proteins that bind to hydrophobic ligands, initiating a signaling cascade, which indirectly influences the making of a functional protein. Cell-surface receptors bind to hydrophilic ligands and the ligand-receptor complex directly enters the nucleus, initiating transcription and translation.
22 .
Cells grown in the laboratory are mixed with a dye molecule that is unable to pass through the plasma membrane. If a ligand is added to the cells, the dye is then observed entering the cells. Interpreting this result, what type of receptor did the ligand bind to on the cell surface?
  1. G-protein-linked R receptor
  2. ligand-gated ion channel
  3. voltage-gated ion channel
  4. receptor tyrosine kinase
23 .
The same second messengers are used in many different cells, but the response to those second messengers differs in each cell. How is this possible? Compare explanations below and select the one that supports this claim of varying responses.
  1. Different cells produce the same receptors, which bind to the same ligands but have differing responses in each cell type.
  2. Cells produce variants of a particular receptor for a particular ligand through alternative splicing, resulting in a different response in each cell.
  3. Cells contain different genes, which produce different receptors that bind to the same ligand, activating different responses in each cell.
  4. Cells produce different receptors that bind to the same ligand, or the same receptor that binds to the same ligand with different signaling components, activating different responses in each cell.
24 .
Consider the interconnected events involved in intracellular signalling. Predict what would happen if the intracellular domain of a cell-surface receptor was switched with the domain from another receptor.
  1. It would activate the pathway normally triggered by the receptor that contributed the intracellular domain.
  2. It would activate the same pathway even after the intracellular domain was changed with the domain from another receptor.
  3. The receptor would become mutated and thus non-functional, not activating any pathway.
  4. The receptor would become mutated and lead to continuous cell signaling, even in the absence of a ligand.
25 .
Refer to Figure 9.10
.
Analyze the process pictured. Use it to explain how a chemical that blocks the binding of epidermal growth factor (EGF) to the EGF receptor, EGFR, would interfere with the replication of cancerous cells that overexpress EGFR.
  1. It would activate the EGFR pathway.
  2. It would block the EGFR pathway
  3. It would have no effect and the EGFR pathway so would not interfer with replication of cancerous cells.
  4. It would lead to overexpression of the EGFR pathway.
26 .
Analyze the connection between cell signaling pathways and cell growth to answer the following question: How does the extracellular matrix control the growth of cells?
  1. Contact of receptors with the extracellular matrix maintains equilibrium of the cell and provides optimal pH for the growth of the cells.
  2. Contact of the receptor with the extracellular matrix helps maintain concentration gradients across membrane, resulting in the flow of ions.
  3. The extracellular matrix provides nutrients for the cell, supporting receptor function.
  4. The extracellular matrix connects the cell to the external environment and ensures correct positioning of the cell to prevent metastasis.
27 .
Refer to Figure 9.14
.
Signal transduction pathways regulate a broad range of cellular activities, including the MAP kinase cascade pictured here. Propose an example for each one of the following effects of a cell signal: on protein expression, cellular metabolism, and cell division.
  1. protein expression: binding of epinephrine (adrenaline) to a G-protein-linked receptor; cellular metabolism: the MAP-kinase cascade; cell division: promoted by the binding of the EGF to its receptor tyrosine kinase
  2. protein expression: the MAP-kinase cascade; cellular metabolism- binding of epinephrine (adrenaline) to a G-protein-linked receptor; cell division promoted by the binding of the EGF to its receptor tyrosine kinase
  3. protein expression: binding of the EGF to its receptor tyrosine kinase; cellular metabolism: the MAP-kinase cascade; cell division: FAS-RAS signaling.
  4. protein expression: RAS signaling; cellular metabolism: binding of the EGF to its receptor tyrosine kinase promotes an increase; cell division: binding of epinephrine (adrenaline) to a G-protein-linked receptor.
28 .
Signal transduction pathways regulate a range of responses in cells. The mitogen-activated protein (MAP) kinase cascade triggered by receptor tyrosine kinases (RTKs) results in cell division. Predict likely scenarios of abnormalities in the MAPK pathway leading to uncontrolled cell proliferation.
  1. gain of function mutation in RAS protein, mutation in I κ -B, loss of function mutation in genes for MAPK kinase pathway, regulated phosphorylation cascade
  2. loss of function mutation in RAS protein and gain of function mutation in RAF protein, I κ -B permanently bound to NF- κ B, regulated phosphorylation cascade
  3. RAS protein unable to hydrolyze its bound GTP, loss of function mutation in I κ -B, gain of function mutation in genes for MAPK kinase pathway, unregulated phosphorylation cascade
  4. unregulated phosphorylation cascade, loss of function mutation in RAS and RAF protein, mutation in genes for MAPK kinase pathway, regulated phosphorylation cascade
29 .
Yeast is considered a good model for learning about signaling in humans. Differentiate between the options provided to propose the characteristics of yeast that support their role as a model.
  1. Yeasts are prokaryotes. They have a short life cycle, reproduce rapidly, and share similarities with humans in certain regulating mechanisms.
  2. Yeasts are eukaryotes. They have a short life cycle, are easy to grow, and share similarities with humans in certain regulating mechanisms.
  3. Yeasts are multicellular organisms. They have a predictable life cycle, are easy to grow, and offer contrasts to humans in certain regulating mechanisms.
  4. Yeasts are single-celled organisms. They have a complex life cycle like that of humans and share similarities in regulating mechanisms.
30 .
Connect what you have learned about signaling pathways to provide a hypothesis for why signaling differs between types of organisms. Specifically, why is signaling in multicellular organisms more complicated than signaling in single-celled organisms?
  1. Multicellular organisms coordinate between distantly located cells; single-celled organisms communicate only with nearby cells.
  2. Multicellular organisms involve receptors for signaling; single-celled organisms communicate by fusion of plasma membrane with the nearby cells.
  3. Multicellular organisms require more time for signal transduction than single-celled organisms, as they show compartmentalization.
  4. Multicellular organisms require more time for signal transduction than single-celled organisms, as they lack compartmentalization.
31.

Biofilms are a prominent danger in infectious disease treatment today because it is difficult to find drugs that can penetrate the biofilm. What characteristics would a drug have if it aimed to prevent bacteria from forming biofilms in the first place? Explain your answer.

32 .
Using the yeast mating factor as an example, support the hypothesis that signaling pathways appeared early in evolution and are well-conserved. Evaluate the explanations provided to select the one that best supports the hypothesis.
  1. Signaling in yeast uses the RTK pathway and is evolutionarily conserved, like insulin signaling in humans.
  2. Signaling in yeast uses G-protein coupled receptors for signaling and is evolutionarily conserved, like insulin signaling in humans.
  3. Signaling in yeast uses an endocrine pathway and is evolutionarily conserved, like insulin signaling in humans.
  4. Mating factor in yeast uses an autocrine signaling pathway and is evolutionarily conserved.
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