Question 1

Which of the following best describes the structure of the cell membrane according to the fluid mosaic model?

Accepted Answer

A double layer (bilayer) of phospholipids with proteins and carbohydrates interspersed throughout.

Question 2

Which of the following is a primary function of the cell membrane?

Accepted Answer

Providing structural support, regulating exchange, and facilitating communication between the cell and its environment.

Question 3

A patient is experiencing difficulty with cell-to-cell communication. Which component of the cell membrane is most likely malfunctioning?

Accepted Answer

Integral membrane proteins

Question 4

Which of the following best explains why the cell membrane is described as 'selectively permeable'?

Accepted Answer

It allows some substances to cross more easily than others due to the arrangement of lipids and proteins.

Question 5

Which of the following statements about negative feedback loops is correct?

Accepted Answer

They counteract the initial stimulus to restore the system to its set point.

Question 6

During a reflex control of blood pressure, which of the following sequences is correct?

Accepted Answer

Sensor → Integrating center → Target → Response

Question 7

Which type of membrane protein is most likely to function as a channel for ions to cross the membrane?

Accepted Answer

Transmembrane protein

Question 8

A researcher increases the cholesterol content in a cell membrane. What is the most likely effect on the membrane's properties?

Accepted Answer

The membrane becomes more rigid and less permeable.

Question 9

Which of the following best describes a feedforward control system?

Accepted Answer

A system that predicts a change and initiates a response in anticipation.

Question 10

If a cell membrane is composed of 40% lipids, 55% proteins, and 5% carbohydrates, which statement is most accurate?

Accepted Answer

The membrane is likely to be metabolically active due to its high protein content.

Question 11

Which of the following equations best represents the relationship between stimulus, response, and feedback in a negative feedback loop?

Accepted Answer

$$Response = -Stimulus$$

Question 12

A mutation causes a cell to lack glycolipids and glycoproteins on its membrane surface. Which function would be most directly impaired?

Accepted Answer

Cell recognition and communication

Question 13

Which of the following is a characteristic of lipid rafts in the cell membrane?

Accepted Answer

They are enriched in sphingolipids and proteins important for cell signaling.

Question 14

Which of the following best explains why positive feedback is not typically homeostatic?

Accepted Answer

It reinforces the stimulus, moving the system further from its set point.

Question 15

A patient has a genetic defect in their GPI anchor proteins. Which of the following is most likely to be affected?

Accepted Answer

Anchoring of certain proteins to the external surface of the membrane via glycosylphosphatidylinositol

Question 16

Which of the following is true regarding circadian rhythms?

Accepted Answer

They are predictable cycles of changes in physiological variables over a 24-hour period.

Question 17

Which of the following best describes the role of membrane carbohydrates?

Accepted Answer

They serve as recognition sites for cell-cell interactions.

Question 18

A cell is exposed to a toxin that disrupts the hydrophobic interactions in the membrane. What is the most likely immediate effect?

Accepted Answer

The membrane will lose its bilayer structure and become leaky.

Question 19

Which of the following is a correct statement about the relationship between membrane protein content and metabolic activity?

Accepted Answer

The more metabolically active a membrane is, the more proteins it contains.

Question 20

A scenario: During exercise, the body anticipates an increase in oxygen demand and increases heart rate before oxygen levels drop. Which control mechanism is this an example of?

Accepted Answer

Feedforward control

Control Systems and Cell Membranes: Structure and Function

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