Question 1

Which of the following best describes quorum sensing in bacteria?

Accepted Answer

A mechanism where bacteria count their population density using chemical signals and coordinate gene expression when a threshold is reached.

Question 2

Which hormone type can diffuse directly through the plasma membrane and bind to intracellular receptors?

Accepted Answer

Fat-soluble hormones

Question 3

A patient has a tumor in the pituitary gland causing excessive secretion of human growth hormone (HGH). Which condition is most likely to develop?

Accepted Answer

Gigantism

Question 4

Which brain region is primarily responsible for regulating automatic survival functions such as heart rate and breathing?

Accepted Answer

Medulla

Question 5

During the depolarization phase of a neuronal action potential, which event occurs?

Accepted Answer

Na+ channels open and Na+ floods into the cell, making the inside positive

Question 6

Which of the following best describes the function of the myelin sheath in neurons?

Accepted Answer

It insulates the axon and increases the speed of signal transmission.

Question 7

Which of the following is an example of endocrine signaling?

Accepted Answer

A cell releasing a hormone into the bloodstream to affect distant target cells

Question 8

Which sequence correctly represents the three main stages of cell signaling?

Accepted Answer

Reception, transduction, response

Question 9

How does a ligand-gated ion channel receptor function?

Accepted Answer

A ligand binds and the channel opens, allowing ions to flow down their concentration gradient into the cell

Question 10

In G-protein-linked receptor signaling, what event activates the G-protein?

Accepted Answer

GTP replaces GDP on the G-protein after the receptor is activated by ligand binding

Question 11

Which process activates receptor tyrosine kinases (RTKs)?

Accepted Answer

Dimerization: a signal molecule binds two receptor monomers, pulling them together to activate the catalytic domain

Question 12

What is the role of cAMP in the epinephrine signaling pathway?

Accepted Answer

It acts as a second messenger that relays and amplifies the signal after the receptor is activated

Question 13

Which of the following best describes apoptosis?

Accepted Answer

A programmed form of cell death, integrated by signaling pathways, that avoids triggering an inflammatory response

Question 14

A mutation causes a cell to lose the ability to produce protein kinases. Which step in a typical signal transduction pathway would be most directly affected?

Accepted Answer

Phosphorylation cascade during transduction

Question 15

Which of the following is a real-life example of signal amplification in cell signaling?

Accepted Answer

A single molecule of epinephrine triggers the breakdown of thousands of glycogen molecules in a liver cell

Question 16

Which of the following best explains why caffeine keeps you awake?

Accepted Answer

Caffeine blocks the A2A receptor, preventing the tiredness signaling cascade from starting.

Question 17

Which of the following is NOT a function of the hypothalamus?

Accepted Answer

Sorting and relaying sensory information to the cerebellum

Question 18

Which scenario is an example of paracrine signaling?

Accepted Answer

A cell releasing growth factors that affect nearby cells

Question 19

Which part of the neuron receives signals from other neurons?

Accepted Answer

Dendrite

Question 20

Which of the following best describes the effect of a mutation that prevents dimerization of receptor tyrosine kinases (RTKs)?

Accepted Answer

The receptor would not become active, and the cell would not respond to the signal.

Cell Communication and Signal Transduction in Biology

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