Q: Which equation correctly represents the conversion of ATP to cyclic AMP (cAMP) by adenylyl cyclase during signal transduction?

$$\text{ATP} \rightarrow \text{cAMP} + \text{PP}_i$$

Q: Which equation represents the phosphorylation of a protein by a protein kinase?

$$\text{Protein} + \text{ATP} \rightarrow \text{Phosphorylated protein} + \text{ADP}$$

Question 1

Which of the following best describes the sequence of events in cell signaling that enables an impala to escape from a cheetah, as shown in the provided images?

Accepted Answer

Signal reception → Signal transduction → Cellular response

Question 2

In the context of cell signaling, what is the primary function of a G protein-coupled receptor (GPCR) as illustrated in the images?

Accepted Answer

To transmit signals from extracellular molecules to intracellular relay molecules via G proteins

Question 3

Which equation correctly represents the conversion of ATP to cyclic AMP (cAMP) by adenylyl cyclase during signal transduction?

Accepted Answer

$$	ext{ATP} ightarrow 	ext{cAMP} + 	ext{PP}_i$$

Question 4

Which of the following is a real-life example of signal amplification in a cell, as seen in the impala’s flight response?

Accepted Answer

One epinephrine molecule binding to a receptor leads to the activation of thousands of glucose molecules from glycogen

Question 5

Which type of cell signaling involves direct cytoplasmic connections between adjacent cells, as shown in the images?

Accepted Answer

Cell junction signaling (gap junctions in animals, plasmodesmata in plants)

Question 6

What is the role of protein kinases in a phosphorylation cascade during signal transduction?

Accepted Answer

They transfer phosphate groups from ATP to proteins

Question 7

Which of the following best explains why calcium ions ($$	ext{Ca}^{2+}) $$can act as effective second messengers in cell signaling?

Accepted Answer

Their concentration in the cytosol is much lower than outside the cell, so small changes have large effects

Question 8

Which of the following is a correct description of the function of scaffolding proteins in signal transduction?

Accepted Answer

They increase signal transduction efficiency by grouping together different proteins involved in the same pathway

Question 9

A ligand-gated ion channel receptor opens in response to a signaling molecule. Which ions are commonly allowed through these channels, as shown in the images?

Accepted Answer

Na+ and Ca2+

Question 10

Which of the following statements about intracellular receptors is correct?

Accepted Answer

They bind to small or hydrophobic molecules, such as steroid hormones, that can cross the membrane

Question 11

Which equation represents the phosphorylation of a protein by a protein kinase?

Accepted Answer

$$	ext{Protein} + 	ext{ATP} ightarrow 	ext{Phosphorylated protein} + 	ext{ADP}$$

Question 12

Which of the following is NOT a plausible outcome of cell signaling specificity, as illustrated in the images?

Accepted Answer

All cells respond identically to the same signal regardless of their protein composition

Question 13

Which of the following best describes the termination of a cell signaling pathway?

Accepted Answer

The signal is terminated when the concentration of external signaling molecules falls and unbound receptors revert to an inactive state

Question 14

Which of the following is a correct example of paracrine signaling?

Accepted Answer

Growth factors stimulate nearby target cells to grow and divide

Question 15

Which of the following best explains why the impala’s muscle cells rapidly mobilize glucose during a chase?

Accepted Answer

Epinephrine binds to a GPCR, activating a cascade that leads to glycogen breakdown and glucose release

Question 16

Which of the following is a correct description of endocrine signaling?

Accepted Answer

Signaling molecules are released into the bloodstream and act on distant target cells

Question 17

Which of the following best describes the function of a receptor tyrosine kinase (RTK)?

Accepted Answer

It transfers phosphate groups from ATP to tyrosine residues on itself and other proteins

Question 18

Which of the following is a correct example of a second messenger in cell signaling?

Accepted Answer

cAMP, which is produced from ATP by adenylyl cyclase

Question 19

Which of the following best describes the role of a hormone-receptor complex in the nucleus?

Accepted Answer

It acts as a transcription factor, turning genes on or off

Cell Communication and Signal Transduction

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