Diffusion, osmosis, active transport

• What is diffusion?

  Net movement of particles from high to low concentration
• What happens to molecules over time if left alone?


  They spread out due to random motion
• What is meant by 'net movement' in diffusion?

  Movement of all particles considered as a group
• Can diffusion occur in gases and liquids?

  Yes
• What happens when you spray perfume in a room?

  It diffuses quickly across the room
• What occurs when food coloring is added to water?

  It diffuses until the water is uniform
• What type of membranes allow diffusion?

  Partially permeable membranes
• What types of molecules can generally diffuse through cell membranes?

  Small molecules like water and glucose
• Why can't larger molecules diffuse through cell membranes?

  They are too big to fit through
• Is diffusion an active or passive process?

  Passive process
• What does a larger concentration gradient indicate?

  Higher rate of diffusion
• How does temperature affect the rate of diffusion?

  Higher temperature increases diffusion rate
• Why does a larger surface area increase diffusion rate?

  More particles can diffuse at once
• How does surface area relate to diffusion in two boxes of the same volume?

  Larger surface area allows more particles to diffuse
• What are the three factors that affect the rate of diffusion?

  • Concentration gradient
  • Temperature
  • Surface area
• What is diffusion?

  Net movement of particles from high to low concentration
• How do oxygen and glucose molecules enter a cell?

  By diffusing down their concentration gradient
• What is osmosis?

  Diffusion of water molecules across a membrane
• What defines the direction of osmosis?

  From higher water concentration to lower water concentration
• What does water concentration refer to?

  Amount of water compared to solutes
• What are solutes?

  Molecules like sugars or salts dissolved in water
• How does solute concentration affect water concentration?

  • Higher solute concentration = lower water concentration
  • Lower solute concentration = higher water concentration
• If one beaker has one solute particle and another has three, which has higher solute concentration?

  The beaker with three solute particles
• What determines the concentration of water in a solution?

  The proportion of water compared to solutes
• How does the concentration of water inside a cell compare to the outside?

  Inside has lower water concentration than outside
• What happens to water particles due to concentration differences?

  They diffuse from outside to inside the cell
• What is the process of water moving from high to low concentration called?

  Osmosis
• What is active transport?

  Movement of molecules against their concentration gradient
• How does active transport differ from diffusion?

  Active transport requires energy, diffusion does not
• What analogy is used to describe diffusion?

  Water flowing downhill
• What is the energy source for active transport?

  Energy from cellular respiration
• Where does cellular respiration mainly occur?

  In the mitochondria
• What are ATP molecules compared to?

  Little batteries for energy transport
• What is the definition of active transport?

  • Movement of molecules across a cell membrane
  • From lower concentration to higher concentration
  • Requires energy from cellular respiration
• Why do plants need to absorb water and mineral ions?

  To survive and grow
• What are root hair cells adapted for?

  Absorbing water and mineral ions
• Why can't plants absorb minerals by diffusion?

  Minerals are at higher concentration inside the cell
• What is the role of mitochondria in root hair cells?

  To provide energy for active transport
• What adaptations do root hair cells have for their function?

  • Large surface area for absorption
  • Numerous mitochondria for energy production
• What is the function of chlorophyll in plants?

  To produce energy through photosynthesis