Question 1

Which of the following best describes the three stages of cell signaling, as illustrated in the impala's response to seeing a cheetah?

Accepted Answer

Reception, Transduction, Response

Question 2

In the scenario where an impala senses a cheetah and epinephrine is released, which cellular process is directly responsible for converting glycogen to glucose in muscle cells?

Accepted Answer

Activation of glycogen phosphorylase by a phosphorylation cascade

Question 3

Gap junctions in animal cells and plasmodesmata in plant cells are examples of which type of cell communication?

Accepted Answer

Direct contact signaling

Question 4

Which of the following is a key feature of G protein-coupled receptors (GPCRs)?

Accepted Answer

They span the plasma membrane with seven transmembrane helices

Question 5

What is the role of adenylyl cyclase in the signal transduction pathway initiated by epinephrine?

Accepted Answer

It converts ATP to cyclic AMP (cAMP)

Question 6

Which equation correctly represents the conversion catalyzed by adenylyl cyclase?

Accepted Answer

$$\mathrm{ATP} \rightarrow \mathrm{cAMP} + \mathrm{PP_i}$$

Question 7

Which of the following best explains why calcium ions ($$\mathrm{Ca$$^{2+}$$}) $$can act as second messengers in cells?

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 function of receptor tyrosine kinases (RTKs)?

Accepted Answer

They transfer phosphate groups from ATP to tyrosine residues on proteins

Question 9

A ligand-gated ion channel opens in response to a signaling molecule. What is the immediate result?

Accepted Answer

Specific ions such as $$\mathrm{Na^+} or$$ $$\mathrm{Ca$$^{2+}$$}$$ flow through the channel

Question 10

Which of the following statements about intracellular receptors is correct?

Accepted Answer

They are activated by small or hydrophobic molecules that can cross the plasma membrane

Question 11

In a phosphorylation cascade, what is the role of protein kinases?

Accepted Answer

They transfer phosphate groups from ATP to proteins

Question 12

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

Accepted Answer

$$	ext{Protein} + 	ext{ATP} ightarrow 	ext{Protein-P} + 	ext{ADP}$$

Question 13

Which of the following best describes the amplification of a signal in a cell signaling pathway?

Accepted Answer

Each step in the pathway activates more molecules than the previous step

Question 14

Scaffolding proteins enhance the efficiency of signal transduction by:

Accepted Answer

Grouping together different proteins involved in the same pathway

Question 15

Which of the following is NOT a mechanism for terminating a cell signaling response?

Accepted Answer

Increasing the concentration of external signaling molecules

Question 16

A cell receives two different signals that activate two pathways. These pathways interact and modify each other's responses. This phenomenon is known as:

Accepted Answer

Cross-talk

Question 17

Which of the following is a real-life example of endocrine signaling?

Accepted Answer

Release of insulin by the pancreas, which travels through the bloodstream to target cells

Question 18

Which of the following best explains why the same signaling molecule can produce different responses in different cell types?

Accepted Answer

Different cells have different collections of proteins and pathways

Question 19

Which of the following is a correct sequence for the epinephrine-induced breakdown of glycogen in muscle cells?

Accepted Answer

Epinephrine → GPCR → G protein → Adenylyl cyclase → cAMP → Protein kinase A → Phosphorylase kinase → Glycogen phosphorylase → Glycogen breakdown

Cell Communication and Signal Transduction in Biology

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