Why do hormones in the bloodstream affect only specific target cells?

Answer: Only target cells express the receptor for that hormone Specificity comes from receptor expression: cells without the receptor can't respond.

Ligand-gated ion channels respond to ligand binding by

Answer: Opening or closing to permit ion flow Ligand binding causes a conformational change that opens (or closes) the channel, altering ion flow and membrane potential.

Hydrophilic signal molecules typically bind to

Answer: Cell-surface (membrane) receptors Hydrophilic ligands cannot cross the membrane and bind receptors on the outside. Hydrophobic ligands (e.g., steroids) cross the membrane and bind intracellular receptors.

AP Biology · Topic 4.2

Introduction to Signal Transduction Practice

Part of Cell Communication and Cell Cycle.(IST-3.B)

Practice questions

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Sample questions

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Sample 1difficulty 2/5
$Why do hormones in the bloodstream affect only specific target cells?$
- A
  $Hormones avoid non-target cells$
- B
  $Only target cells touch the bloodstream$
- C
  $Only target cells express the receptor for that hormone$
  check_circle
- D
  $Hormones are broken down by non-target cells$
Why
$Specificity comes from receptor expression: cells without the receptor can't respond.$
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Sample 2difficulty 2/5
$Ligand-gated ion channels respond to ligand binding by$
- A
  $Opening or closing to permit ion flow$
  check_circle
- B
  $Releasing transcription factors$
- C
  $Activating second messengers$
- D
  $Phosphorylating relay proteins$
Why
$Ligand binding causes a conformational change that opens (or closes) the channel, altering ion flow and membrane potential.$
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Sample 3difficulty 2/5
$Hydrophilic signal molecules typically bind to$
- A
  $Ribosomal binding subunits$
- B
  $Cell-surface (membrane) receptors$
  check_circle
- C
  $Intracellular nuclear receptors$
- D
  $Mitochondrial inner membrane$
Why
$Hydrophilic ligands cannot cross the membrane and bind receptors on the outside. Hydrophobic ligands (e.g., steroids) cross the membrane and bind intracellular receptors.$
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Sample 4difficulty 2/5
$The three stages of cell signaling, in order, are$
- A
  $Reception, response, transduction$
- B
  $Response, reception, transduction$
- C
  $Reception, transduction, response$
  check_circle
- D
  $Transduction, reception, response$
Why
$Signal molecule binds receptor (reception); intracellular cascade relays the signal (transduction); cell alters gene expression or activity (response).$
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Sample 5difficulty 2/5
$The diagram outlines the three classic stages of cell signaling proposed by Earl Sutherland.$
$Which stage involves the conversion of an extracellular signal into intracellular molecular events?$
- A
  $Secretion$
- B
  $Transduction$
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- C
  $Reception$
- D
  $Response$
Why
$Transduction converts the bound ligand signal into a series of intracellular changes (often a phosphorylation cascade) that ultimately lead to the cellular response.$
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