Cell Biology: Function and Transport Processes

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Which of the following accurately describes the function of intermediate filaments within a cell?

Generating contractile forces by interacting with myosin.
Facilitating the movement of vesicles using kinesin and dynein.
Strengthening the cell, maintaining its shape, and stabilizing the position of organelles. (correct)
Forming the spindle apparatus during cellular division to separate chromosomes.

During filtration in the capillaries, what primarily drives the movement of fluid and small molecules from the blood into the interstitium?

Osmotic pressure exerted by proteins in the interstitium.
Active transport mechanisms within the capillary walls.
The concentration gradient of large molecules in the blood.
Blood pressure, creating a pressure difference across the capillary membrane. (correct)

How do microtubules contribute to the process of cellular division?

By providing mechanical strength to the cell membrane during cleavage.
By initiating the process of cytokinesis through actin filament contraction.
By directly synthesizing new DNA for the daughter cells.
By forming the spindle apparatus that attaches to and separates chromosomes. (correct)

Microvilli are cellular extensions found in various locations within the body. What is the primary function of microvilli?

To increase the surface area of the cell for absorption or secretion. (B) Signup and view all the answers

If a cell were treated with a drug that inhibits the function of kinesin and dynein, which of the following processes would be most directly affected?

The movement of vesicles within the cell. (B) Signup and view all the answers

A certain cell type utilizes a carrier protein to transport glucose across its plasma membrane. If a similar molecule that also binds to the same carrier protein is introduced, what immediate effect would you expect to observe?

The rate of glucose transport will decrease due to competitive inhibition. (C) Signup and view all the answers

A researcher is studying a new transport protein and observes that its rate of transport increases with substrate concentration up to a certain point, beyond which the rate plateaus. This observation is characteristic of what property?

Saturation (A) Signup and view all the answers

Which of the following transport mechanisms directly utilizes ATP to move substances against their concentration gradient?

Primary active transport (B) Signup and view all the answers

In secondary active transport, the movement of glucose against its concentration gradient is indirectly powered by which of the following?

The electrochemical gradient of Na+ established by the Na+/K+ ATPase. (C) Signup and view all the answers

A cell needs to secrete a large protein, such as a hormone, into the extracellular space. Which transport mechanism is most likely involved in this process?

Exocytosis (C) Signup and view all the answers

A macrophage engulfs a bacterium through what process?

Phagocytosis (D) Signup and view all the answers

A nerve cell at rest has a higher concentration of $Na^+$ ions outside the cell and a higher concentration of $K^+$ ions inside the cell. Which transport mechanism is primarily responsible for maintaining this concentration gradient?

The $Na^+/K^+$ exchange pump (C) Signup and view all the answers

A researcher observes that a particular cell type internalizes small droplets of extracellular fluid. Which process is most likely responsible for this observation?

Pinocytosis (C) Signup and view all the answers

In osmosis, what primarily drives the movement of water across a semipermeable membrane?

The difference in water concentration between two areas. (C) Signup and view all the answers

Which of the following best describes the relationship between solute concentration difference and osmotic pressure?

The greater the difference in solute concentration, the greater the osmotic pressure. (B) Signup and view all the answers

If a cell is placed in a hypertonic solution, what net movement of water will occur, and what will be the effect on the cell?

Water moves out of the cell, causing it to shrivel or crenate. (D) Signup and view all the answers

A cell is placed in a solution, and it swells and eventually hemolyzes. What type of solution is it?

Hypotonic solution (D) Signup and view all the answers

What characteristics of molecules necessitate facilitated diffusion?

Large or polar molecules that cannot directly pass through the lipid bilayer. (A) Signup and view all the answers

Which distinguishes channel proteins from carrier proteins in facilitated diffusion?

Channel proteins form pores through the membrane, while carrier proteins undergo conformational changes to transport molecules. (A) Signup and view all the answers

What is the primary role of non-gated channels in the plasma membrane?

To provide selective permeability to ions when the membrane is at rest. (C) Signup and view all the answers

How do gated channel proteins differ from non-gated channel proteins?

Gated channels open or close in response to a stimulus, while non-gated channels are always open. (A) Signup and view all the answers

How do unsaturated hydrophobic fatty acid tails in the plasma membrane contribute to its function?

By creating kinks that enhance membrane fluidity. (D) Signup and view all the answers

What characteristic distinguishes integral proteins from peripheral proteins in a plasma membrane?

Integral proteins completely span the membrane, whereas peripheral proteins are bound to its surface. (B) Signup and view all the answers

If a cell is exposed to a toxin that disrupts the function of recognition proteins, which cellular process would be MOST directly affected?

The cell's ability to be identified as normal or abnormal by the immune system. (A) Signup and view all the answers

How do receptor proteins facilitate cell communication?

By binding to specific ligands and initiating a cellular response. (D) Signup and view all the answers

Which of the following is a primary function of the glycocalyx?

Facilitating cell-to-cell recognition and adhesion. (A) Signup and view all the answers

A scientist discovers a new cell membrane that is freely permeable. What can be said about this membrane?

It allows any substance to pass through without restriction. (A) Signup and view all the answers

What three criteria determine whether a substance can permeate a membrane?

Lipid solubility, size/shape and electrical charge. (B) Signup and view all the answers

How does osmosis differ from diffusion?

Osmosis specifically describes the movement of water, whereas diffusion can involve any small hydrophobic molecule, small polar molecule or gas. (C) Signup and view all the answers

What is the primary role of the Golgi apparatus in a cell?

Modifying, sorting, and packaging lipids and proteins into vesicles. (B) Signup and view all the answers

Which of the following cellular components is primarily involved in the self-destruction of damaged cells through the release of digestive enzymes?

Lysosomes (A) Signup and view all the answers

A cell is exposed to a toxin that generates an excess of free radicals. Which organelle would primarily be involved in neutralizing these free radicals?

Peroxisomes (B) Signup and view all the answers

During strenuous exercise, muscle cells require a significant amount of ATP. Which organelle is primarily responsible for meeting this increased energy demand?

Mitochondria (A) Signup and view all the answers

If a cell is unable to recycle damaged organelles, which of the following organelles is most likely malfunctioning?

Lysosomes (B) Signup and view all the answers

Which of the following structures is primarily responsible for moving fluids across the cell surface?

Cilia (C) Signup and view all the answers

A cell requires a large quantity of a specific protein to be secreted outside the cell. Which organelle would likely be most prominent in this cell?

Rough endoplasmic reticulum (RER) (A) Signup and view all the answers

Which of the following processes is NOT a primary function of the smooth endoplasmic reticulum (SER)?

Protein synthesis (D) Signup and view all the answers

How do materials typically move from the endoplasmic reticulum to the Golgi apparatus?

Via transport vesicles that bud off from the ER. (A) Signup and view all the answers

Which of the following best describes the function of nuclear pores?

They regulate the movement of substances between the nucleus and the cytoplasm. (A) Signup and view all the answers

A liver cell is exposed to a toxin. Which organelle would be critical in detoxifying this substance?

Smooth endoplasmic reticulum (SER) (D) Signup and view all the answers

What is the primary difference between fixed and free ribosomes?

Fixed ribosomes produce proteins for secretion of the cell, while free ribosomes produce proteins for use inside the cell. (B) Signup and view all the answers

What is the composition of ribosomes?

Protein and RNA (A) Signup and view all the answers

Concentration Gradient Movement

Movement from high to low concentration; rate depends on gradient difference.

Osmosis

Passive movement of water across a semipermeable membrane from high to low water concentration.

Osmotic Pressure

Pressure from particles in a solution that influences water movement. More particles = greater pressure.