Cell Membrane Structure & Transport Quiz
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Questions and Answers

Which type of passive transport requires specific protein channels?

  • Simple diffusion
  • Facilitated diffusion (correct)
  • Osmosis
  • Active transport

What is the driving force behind diffusion?

  • Electrochemical gradients
  • Osmotic pressure
  • Concentration gradients
  • Kinetic energy of molecules (correct)

In which direction do materials move during passive transport?

  • From low to high concentration
  • Against the concentration gradient
  • From high to low concentration (correct)
  • Randomly in all directions

What factor does NOT affect the rate of diffusion?

<p>Electric charge of molecules (B)</p> Signup and view all the answers

Which of the following molecules is most likely to undergo simple diffusion?

<p>Oxygen (O2) (A)</p> Signup and view all the answers

What condition must be met for diffusion to stop?

<p>When equilibrium is reached in particle distribution (C)</p> Signup and view all the answers

In which situation would osmosis occur?

<p>When there is high solute concentration in the cytoplasm (B)</p> Signup and view all the answers

Which type of transport does NOT require energy from ATP?

<p>Both B and C (C)</p> Signup and view all the answers

What function does the cell membrane primarily serve?

<p>Maintains homeostasis (C)</p> Signup and view all the answers

Which of the following statements about the fluid mosaic model is true?

<p>The cell membrane is flexible and has embedded molecules. (C)</p> Signup and view all the answers

What is the role of glycoproteins in the cell membrane?

<p>Cell recognition and identification (B)</p> Signup and view all the answers

What characterizes the polar regions of the plasma membrane?

<p>Water-soluble hydrophilic heads facing inside and outside (D)</p> Signup and view all the answers

Which of the following correctly describes nonpolar and polar interactions in the cell membrane?

<p>Nonpolar molecules do not interact with polar molecules. (D)</p> Signup and view all the answers

Which part of the plasma membrane is hydrophobic?

<p>Fatty acid tails (D)</p> Signup and view all the answers

What type of transport involves the movement of materials across the cell membrane without energy input?

<p>Passive transport (C)</p> Signup and view all the answers

Which is NOT a characteristic of the cell membrane?

<p>Completely solid structure (B)</p> Signup and view all the answers

What happens to a cell placed in a hypertonic solution?

<p>Water diffuses out of the cell causing it to shrink. (A)</p> Signup and view all the answers

Which of the following correctly describes hypotonic solutions?

<p>Solute concentration is lower outside the cell. (A)</p> Signup and view all the answers

What type of transport is primarily used for the movement of glucose across a cell membrane?

<p>Facilitated diffusion (A)</p> Signup and view all the answers

What is the result of placing an animal cell in a hypotonic solution?

<p>The cell swells and may burst. (C)</p> Signup and view all the answers

Which solution has equal solute concentrations inside and outside the cell?

<p>Isotonic solution (A)</p> Signup and view all the answers

How do paramecium deal with osmotic pressure?

<p>They possess contractile vacuoles to expel excess water. (C)</p> Signup and view all the answers

What is turgor pressure?

<p>Force exerted by the cell wall due to water intake. (B)</p> Signup and view all the answers

What is the significance of kidneys in maintaining isotonic blood?

<p>They remove excess salt and water from the blood. (D)</p> Signup and view all the answers

What happens to an animal cell when it is placed in a hypotonic solution?

<p>The cell bursts due to excess water intake. (C)</p> Signup and view all the answers

When a plant cell is placed in a hypotonic solution, what is the primary outcome?

<p>The plant cell becomes turgid and firm. (A)</p> Signup and view all the answers

What is the effect on an animal cell placed in a hypertonic solution?

<p>The cell shrinks due to water moving out. (A)</p> Signup and view all the answers

How does an isotonic solution affect a plant or animal cell?

<p>There is no net movement of water into or out of the cells. (D)</p> Signup and view all the answers

What structural feature in plant cells helps prevent them from bursting?

<p>The rigid cell wall. (A)</p> Signup and view all the answers

What happens when a saltwater fish is placed in fresh water?

<p>The fish swells due to an influx of water. (B)</p> Signup and view all the answers

Why do you become thirsty after eating salty food?

<p>Your cells lose water due to hypertonicity. (C)</p> Signup and view all the answers

What is the primary requirement for active transport in cells?

<p>Energy in the form of ATP. (D)</p> Signup and view all the answers

Flashcards

Homeostasis (Cell Membrane Function)

The cell membrane acts as a barrier, controlling what enters and exits the cell, ensuring the cell's internal environment remains stable.

Selectively Permeable Membrane

The cell membrane allows some substances to pass through while blocking others. This selectivity is crucial for maintaining proper cell function.

Protection & Support (Cell Membrane Function)

The cell membrane acts as a protective barrier, shielding the cell from its surroundings. It also provides structural support, maintaining the cell's shape.

Universal Presence of Cell Membrane

All living organisms have a cell membrane, which is essential for cell survival and proper functioning.

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Fluid Mosaic Model

The Fluid Mosaic Model describes the cell membrane as a fluid structure with various molecules embedded within. It's like a mosaic because of its diverse components.

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Lipid Bilayer

The cell membrane is composed of two layers of phospholipids. Each phospholipid has a hydrophilic head and a hydrophobic tail.

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Membrane Proteins

Proteins embedded in the cell membrane perform various functions like transporting materials, speeding up reactions, or recognizing signals.

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Glycoproteins

Glycoproteins are proteins with attached sugar molecules. They play a vital role in cell recognition, like chemical identification cards.

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Passive Transport

The movement of substances across the cell membrane without requiring any energy expenditure by the cell.

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Simple Diffusion

The movement of molecules from a region of higher concentration to a region of lower concentration.

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Facilitated Diffusion

The movement of molecules across the cell membrane through specific protein channels, still moving down the concentration gradient.

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Osmosis

The movement of water molecules across a semi-permeable membrane from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration).

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Concentration Gradient

The difference in the concentration of a substance between two regions. Substances naturally move from a high concentration to a low concentration.

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Equilibrium

The state where the concentration of a substance is equal throughout a given area, meaning there is no longer any movement of substances due to differences in concentration.

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Active Transport

The movement of substances across the cell membrane that requires energy (ATP) to be used by the cell.

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Solute Concentration

The total concentration of all dissolved substances in a solution.

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Hypertonic

A solution with a higher solute concentration than another solution.

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Hypotonic

A solution with a lower solute concentration than another solution.

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Isotonic

A solution with the same solute concentration as another solution.

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Phagocytosis

A type of active transport where cells engulf large particles or microorganisms.

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Pinocytosis

A type of active transport where cells engulf fluids.

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Hypertonic Solution

A solution where the concentration of solutes is higher outside the cell than inside the cell.

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Hypotonic Solution

A solution where the concentration of solutes is lower outside the cell than inside the cell.

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Isotonic Solution

A solution where the concentration of solutes is equal inside and outside the cell.

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Plasmolysis

The shrinking of a cell's cytoplasm due to water loss in a hypertonic environment.

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Cytolysis

The bursting of a cell due to excessive water uptake in a hypotonic environment.

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Turgor Pressure

The pressure exerted by the cell wall on the cell's contents, which helps to maintain the cell's shape and turgidity.

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Contractile Vacuole

A specialized organelle in some protists, like paramecium, responsible for expelling excess water from the cell.

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Study Notes

Cell Membrane Structure & Transport

  • Cell membranes maintain homeostasis and are selectively permeable, providing protection and support. All cells possess a cell membrane, also known as the plasma membrane.

Fluid Mosaic Model

  • The cell membrane is fluid and flexible.
  • Different molecules are embedded within the membrane.
  • The membrane's structure resembles a mosaic.
  • A phospholipid bilayer forms the basic structure. The hydrophilic heads face the watery environments (inside and outside the cell), and the hydrophobic tails face inward.

Glycoproteins

  • Proteins with attached sugars.
  • Function: cell recognition (chemical identification cards), crucial for the immune system.

Structure of the Plasma Membrane

  • Composed of a lipid bilayer (2 layers of phospholipids).
  • Embedded with proteins and cholesterol.
  • The hydrophilic heads face the outside and inside of the cell.
  • Hydrophobic tails make up the middle of the membrane layers.

Types of Membrane Proteins

  • Some accelerate reactions.
  • Some have receptors, recognizing specific molecules.
  • Some transport substances across the membrane (e.g., transporters, enzymes, anchors). Proteins have a variety of functions

Characteristics of Plasma Membrane

  • Polar and non-polar regions:
  • Polar regions (water-soluble): hydrophilic heads; found on the inside and outside of the cell
  • Non-polar regions (water-insoluble): hydrophobic tails; found in the middle of the membrane layers.

Polar & Non-Polar Reactivity

  • Nonpolar molecules do not interact with polar molecules.
  • Oil (nonpolar) does not dissolve in water (polar).
  • Nonpolar molecules interact with other non-polar molecules.

Passive Transport

  • Movement of substances across a membrane without energy (ATP).
  • Substances move from high concentration to low concentration (down the concentration gradient).
  • 3 Types of Passive Transport
    • Simple Diffusion
    • Facilitated Diffusion
    • Osmosis

Diffusion

  • Movement of molecules from a high concentration to a low concentration.

  • Does not require energy (ATP).

  • Driven by kinetic energy from the molecules & atoms.

  • Factors affecting diffusion:

    • Temperature (warmer = faster)
    • Size of molecules (smaller = faster)
    • Type of molecules (e.g., gases like oxygen and carbon dioxide diffuse easily)

  • Diffusion ends when equilibrium is reached, with even distribution of molecules.

Facilitated Diffusion

  • Membrane proteins facilitate (help) the movement of molecules or ions that can't readily pass through the membrane, by moving along the concentration gradient (high to low).

  • Specific channels for particular molecules (e.g., glucose channels allow only glucose to pass).

  • Substances that move by facilitated diffusion: glucose, sodium ions (Na+), chloride ions (Cl-), and potassium (K+).

Osmosis

  • Diffusion of water across a selectively permeable membrane.
  • Water moves from high water concentration to low water concentration (or from low solute concentration to high solute concentration).
  • Does not require energy (ATP).

Active Transport

  • Movement of substances across a membrane that requires energy (ATP).
  • Substances move from a low concentration to a high concentration (against the concentration gradient).
  • 3 types
    • Protein Pumps
    • Endocytosis: -Phagocytosis: "cell eating" (e.g., white blood cells engulfing bacteria) -Pinocytosis: "cell drinking" (taking in fluids & dissolved substances)
    • Exocytosis: Forces material out of the cell (e.g., releasing hormones or wastes).

Protein Pumps

  • Specific membrane proteins that use ATP energy to move ions and molecules against their concentration gradients.
  • Example: Sodium-Potassium Pump

Problems with Cellular Transport- Cystic Fibrosis (CF)

  • CF is a genetic disorder causing problems in transporting chloride ions, resulting in thick mucus build-up, affecting various organs. The CFTR protein is responsible for moving chloride ions, regulating water movement that creates the proper consistency of mucus.

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Cell Membrane and Transport PDF

Description

Test your knowledge on the structure and function of cell membranes with this quiz. Discover the roles of the fluid mosaic model, glycoproteins, and the lipid bilayer in maintaining cellular homeostasis. Perfect for biology students covering cell biology topics.

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