3.2.2 Transport Mechanisms

• What role do carrier proteins play in facilitated diffusion?

  Mediate molecule movement
• What is the primary characteristic of passive transport mechanisms?

  No energy required
• In diffusion, molecules move from an area of high to low concentration
• Osmosis is the movement of water molecules from high to low solute concentration.

  False
• What type of molecules require carrier or channel proteins for facilitated diffusion?

  Large polar molecules
• The rate of diffusion is directly proportional to the concentration gradient
• What distinguishes active transport from passive transport?

  Requires energy
• Primary active transport uses ATP directly to move molecules across the membrane.
• Arrange the steps involved in primary active transport:

  1️⃣ Carrier protein binds ATP

  2️⃣ ATP hydrolysis releases energy

  3️⃣ Carrier protein changes shape

  4️⃣ Molecule is transported across membrane
• What type of protein is involved in secondary active transport?

  Co-transporter protein
• Match the type of active transport with its energy source:

  Primary Active Transport ↔️ ATP

  Secondary Active Transport ↔️ Concentration gradient
• Cell membranes are primarily composed of a phospholipid bilayer.
• Cell membranes regulate transport to ensure correct nutrient supply and waste removal
• What primary structure forms the base of cell membranes?

  Phospholipid bilayer
• Cell membranes regulate transport by allowing all molecules to pass through freely.

  False
• Cell membranes maintain cellular homeostasis by regulating the concentration of ions, nutrients, and waste
• What type of molecule facilitates cell-cell communication through cell membranes?

  Signaling molecules
• Match the transport mechanism with its key features:

  Diffusion ↔️ No energy requirement

  Active Transport ↔️ Moves substances against gradient
• The rate of diffusion is directly proportional to the surface area $A$ and the concentration gradient
• What type of energy is used in active transport to move substances against their concentration gradient?

  ATP
• Passive transport mechanisms require energy to move substances across cell membranes.

  False
• Arrange the following passive transport mechanisms in order of decreasing energy requirement:

  1️⃣ Diffusion

  2️⃣ Osmosis

  3️⃣ Facilitated Diffusion
• What type of gradient does osmosis move water molecules along?

  High to low water
• Facilitated diffusion uses carrier or channel proteins
• Match the passive transport mechanism with its energy requirement and movement direction:

  Diffusion ↔️ No energy requirement

  Osmosis ↔️ High to low water concentration
• The rate of diffusion decreases if the concentration gradient increases.

  False
• What type of molecules can move across cell membranes through diffusion?

  Gases, small non-polar
• The diffusion rate is inversely proportional to the concentration gradient.

  False
• Arrange the steps involved in primary active transport using the sodium-potassium pump as an example:

  1️⃣ Carrier protein binds sodium ions

  2️⃣ ATP hydrolysis releases energy

  3️⃣ Carrier protein changes shape

  4️⃣ Sodium ions are transported out of the cell

  5️⃣ Carrier protein binds potassium ions

  6️⃣ Carrier protein reverts to original shape
• Facilitated diffusion uses carrier or channel proteins to move substances across the membrane without requiring energy
• What are examples of essential substances transported by facilitated diffusion?

  Glucose and amino acids
• Osmosis is driven by differences in solute concentration
• Match the type of solution with its effect on cells:

  Hypotonic ↔️ Cell swells

  Isotonic ↔️ No change

  Hypertonic ↔️ Cell shrinks
• What is the primary structural component of cell membranes?

  Phospholipid bilayer
• The diffusion rate is described by $\text{Rate} =$$kAΔC$, where $ΔC$ represents the concentration gradient
• Passive transport requires energy to move molecules across the membrane.

  False
• Passive transport contrasts with active transport, which uses energy to move molecules against their concentration gradient
• Passive transport mechanisms require energy to move substances across cell membranes.

  False
• Match the passive transport mechanism with its key characteristic:

  Diffusion ↔️ Moves gases and small non-polar molecules

  Osmosis ↔️ Moves water across a membrane

  Facilitated Diffusion ↔️ Requires carrier proteins
• The diffusion rate is described by the formula $\text{Rate} =$$kAΔC$, where $A$ is the surface area and $ΔC$ is the concentration gradient