AP Bio 2.7 Facilitated Diffusion
38 flashcards covering AP Bio 2.7 Facilitated Diffusion for the AP-BIOLOGY Unit 2 section.
Facilitated diffusion is a key concept in cellular biology, defined by the College Board's AP Biology curriculum as the process by which molecules move across a cell membrane through protein channels, without the expenditure of energy. This process is crucial for the transport of polar and charged substances, which cannot easily pass through the lipid bilayer of the membrane. Understanding facilitated diffusion is essential for grasping broader topics in cellular transport mechanisms and membrane dynamics.
On practice exams, questions about facilitated diffusion often appear in multiple-choice format, requiring students to identify characteristics of the process or distinguish it from other forms of transport, such as active transport. A common pitfall is confusing facilitated diffusion with passive diffusion; students may overlook the role of transport proteins, leading to incorrect answers. It's important to remember that while both processes are passive, facilitated diffusion specifically involves these proteins to assist in the movement of substances across membranes. A practical tip for students is to always consider the size and polarity of the molecules involved when determining the mode of transport.
Terms (38)
- 01
What is facilitated diffusion?
Facilitated diffusion is the process by which molecules move across a cell membrane via specific transport proteins, without the expenditure of energy. This process is essential for the transport of polar and charged substances that cannot directly pass through the lipid bilayer (College Board AP CED).
- 02
Which molecules typically require facilitated diffusion?
Polar molecules and ions, such as glucose and sodium ions, typically require facilitated diffusion to cross the cell membrane due to their inability to pass freely through the lipid bilayer (College Board AP CED).
- 03
What role do transport proteins play in facilitated diffusion?
Transport proteins provide a pathway for specific molecules to cross the cell membrane during facilitated diffusion, allowing for selective permeability (College Board AP CED).
- 04
How does facilitated diffusion differ from active transport?
Facilitated diffusion is a passive process that does not require energy, while active transport requires energy to move substances against their concentration gradient (College Board AP CED).
- 05
What is the driving force behind facilitated diffusion?
The driving force behind facilitated diffusion is the concentration gradient, where molecules move from an area of higher concentration to an area of lower concentration (College Board AP CED).
- 06
When does facilitated diffusion occur?
Facilitated diffusion occurs when specific molecules need to cross the cell membrane and cannot do so freely due to their polarity or charge, typically when there is a concentration gradient (College Board AP CED).
- 07
What types of transport proteins are involved in facilitated diffusion?
Channel proteins and carrier proteins are the two main types of transport proteins involved in facilitated diffusion, each serving different types of molecules (College Board AP CED).
- 08
What is the function of channel proteins in facilitated diffusion?
Channel proteins create hydrophilic pathways that allow specific ions or small polar molecules to pass through the membrane during facilitated diffusion (College Board AP CED).
- 09
What is the function of carrier proteins in facilitated diffusion?
Carrier proteins bind to specific molecules and undergo a conformational change to transport the molecule across the membrane during facilitated diffusion (College Board AP CED).
- 10
How does temperature affect facilitated diffusion?
Temperature can influence the rate of facilitated diffusion; generally, as temperature increases, the kinetic energy of molecules increases, leading to a higher rate of diffusion (College Board AP CED).
- 11
What is the significance of facilitated diffusion in cellular processes?
Facilitated diffusion is crucial for maintaining homeostasis within cells by allowing necessary substances to enter and exit the cell efficiently (College Board AP CED).
- 12
Which of the following statements about facilitated diffusion is true?
Facilitated diffusion requires the assistance of transport proteins and occurs down the concentration gradient, without energy input (College Board AP CED).
- 13
In which scenario would facilitated diffusion be necessary?
Facilitated diffusion would be necessary for a cell to uptake glucose from the bloodstream, as glucose is a polar molecule that cannot pass through the lipid bilayer directly (College Board AP CED).
- 14
What happens to the rate of facilitated diffusion when a concentration gradient is increased?
The rate of facilitated diffusion typically increases when the concentration gradient is increased, as more molecules are available to move across the membrane (College Board AP CED).
- 15
Under what conditions can facilitated diffusion become saturated?
Facilitated diffusion can become saturated when all available transport proteins are occupied, limiting the rate of transport despite an increase in substrate concentration (College Board AP CED).
- 16
What is the role of aquaporins in facilitated diffusion?
Aquaporins are specialized channel proteins that facilitate the rapid transport of water molecules across the cell membrane (College Board AP CED).
- 17
How does facilitated diffusion contribute to osmoregulation?
Facilitated diffusion helps maintain osmotic balance by allowing water and solutes to move in and out of cells according to concentration gradients, which is vital for osmoregulation (College Board AP CED).
- 18
What is the relationship between facilitated diffusion and membrane permeability?
Facilitated diffusion increases membrane permeability to specific molecules that cannot diffuse freely, thus enhancing the cell's ability to regulate its internal environment (College Board AP CED).
- 19
Which of the following best describes the specificity of facilitated diffusion?
Facilitated diffusion is highly specific, as transport proteins typically only allow certain molecules to pass through based on size, charge, or shape (College Board AP CED).
- 20
What is the impact of pH on facilitated diffusion?
pH can affect the structure and function of transport proteins, potentially altering the rate of facilitated diffusion for certain molecules (College Board AP CED).
- 21
What happens to a cell in a hypertonic solution regarding facilitated diffusion?
In a hypertonic solution, water will exit the cell via facilitated diffusion through aquaporins, leading to cell shrinkage (College Board AP CED).
- 22
How does facilitated diffusion relate to the concept of selective permeability?
Facilitated diffusion exemplifies selective permeability by allowing only specific molecules to enter or exit the cell, based on the presence of transport proteins (College Board AP CED).
- 23
What is the effect of inhibitors on facilitated diffusion?
Inhibitors that block transport proteins can reduce or halt facilitated diffusion, demonstrating the dependency of this process on functional proteins (College Board AP CED).
- 24
How does facilitated diffusion maintain homeostasis in cells?
Facilitated diffusion maintains homeostasis by regulating the influx and efflux of essential molecules, ensuring proper cellular function (College Board AP CED).
- 25
What is a common example of facilitated diffusion in human physiology?
A common example of facilitated diffusion in human physiology is the uptake of glucose by cells through the GLUT transporters (College Board AP CED).
- 26
What factors can limit the rate of facilitated diffusion?
Factors that can limit the rate of facilitated diffusion include the number of available transport proteins, the concentration gradient, and the affinity of the transport proteins for the substrate (College Board AP CED).
- 27
Which of the following best illustrates facilitated diffusion?
The movement of glucose into a cell through a specific carrier protein in response to a concentration gradient is a clear illustration of facilitated diffusion (College Board AP CED).
- 28
What is the primary difference between passive transport and facilitated diffusion?
The primary difference is that facilitated diffusion specifically involves transport proteins, while passive transport can occur without them (College Board AP CED).
- 29
What happens to the facilitated diffusion process when the concentration gradient is eliminated?
When the concentration gradient is eliminated, facilitated diffusion will cease as there is no driving force for the movement of molecules (College Board AP CED).
- 30
How does facilitated diffusion differ from simple diffusion?
Facilitated diffusion requires specific transport proteins to move molecules across the membrane, while simple diffusion does not (College Board AP CED).
- 31
What is the role of glucose transporters in facilitated diffusion?
Glucose transporters specifically facilitate the movement of glucose across the cell membrane, allowing cells to uptake this essential nutrient (College Board AP CED).
- 32
How does facilitated diffusion support cellular respiration?
Facilitated diffusion supports cellular respiration by allowing glucose to enter cells, where it can be metabolized for energy (College Board AP CED).
- 33
What is the significance of the concentration gradient in facilitated diffusion?
The concentration gradient is crucial in facilitated diffusion as it determines the direction and rate of molecule movement across the membrane (College Board AP CED).
- 34
What type of molecules typically utilize carrier proteins for facilitated diffusion?
Large polar molecules, such as glucose and amino acids, typically utilize carrier proteins for facilitated diffusion across cell membranes (College Board AP CED).
- 35
What occurs when a cell is placed in a hypotonic solution regarding facilitated diffusion?
In a hypotonic solution, water will enter the cell via facilitated diffusion through aquaporins, potentially causing the cell to swell (College Board AP CED).
- 36
How does facilitated diffusion contribute to nutrient absorption in the intestines?
Facilitated diffusion allows for the efficient absorption of nutrients, such as glucose and amino acids, through intestinal epithelial cells (College Board AP CED).
- 37
What is the role of ion channels in facilitated diffusion?
Ion channels are a type of transport protein that facilitate the movement of ions across the membrane, crucial for processes like nerve impulse transmission (College Board AP CED).
- 38
How does facilitated diffusion relate to the concept of dynamic equilibrium?
Facilitated diffusion contributes to dynamic equilibrium by allowing molecules to move in and out of the cell until concentrations are balanced on both sides of the membrane (College Board AP CED).