Diffusion and Osmosis

• What are the three main processes for molecule movement in cells?

  Diffusion, osmosis, and active transport
• What is diffusion?

  Movement from high concentration to low concentration
• How is osmosis defined?

  Movement of water from high to low water potential
• What is active transport?

  Movement from low concentration to high concentration
• Where does oxygen diffuse from and to in the lungs?

  From alveoli to the blood
• What happens to carbon dioxide in the alveoli?

  It diffuses from blood into the alveoli
• What can cross cell membranes during osmosis?

  Water and some small molecules
• What happens to potato cells in pure water?

  They swell and become turgid
• What occurs when potato cells are placed in a concentrated sugar solution?

  Water leaves the cells by osmosis
• Why do plants need turgid cells?

  For structural support to stand upright
• What happens to plant cells in a solution with low water potential?

  Water leaves the cell, becoming flaccid
• How do root hair cells absorb water?

  By osmosis from the soil
• How do animal cells behave in distilled water?

  They may swell and burst
• What happens to animal cells in a low water potential solution?

  Water leaves the cells, causing them to shrivel
• Why can't animal cells become turgid?

  They lack a cell wall
• What is required for active transport?

  Energy to move molecules against a gradient
• What do root hair cells absorb through active transport?

  Mineral ions like nitrates and magnesium
• What factors affect the rate of movement of substances into and out of cells?

  • Surface area to volume ratio
  • Temperature
  • Concentration gradient
• How does surface area to volume ratio affect gas exchange?

  • Large surface area to volume ratio aids gas exchange
  • Unicellular organisms have a small ratio
  • Multicellular organisms need adaptations (e.g., lungs, gills)
• Why do large animals have transport systems?

  To supply oxygen to all cells
• Which animal has a larger surface area to volume ratio, a hamster or a whale?

  A hamster has a larger ratio
• How does temperature affect diffusion?

  Higher temperatures increase diffusion speed
• What is the relationship between concentration gradient and diffusion rate?

  A greater difference increases diffusion rate
• What is the direction of diffusion?

  From high concentration to low concentration
• What is the term for the movement of water across a membrane?

  Osmosis
• What is the main energy source for active transport?

  ATP
• What is the role of proteins in active transport?

  They help move molecules across membranes
• What happens to animal cells in a salt solution?

  They shrivel due to water loss
• What is the effect of osmosis on plant cells in a concentrated solution?

  They lose water and become flaccid
• What is the process of water entering root hair cells called?

  Osmosis
• What happens to plant cells when they are placed in a high water potential solution?

  They become turgid as water enters
• What is the main function of the cell wall in plant cells?

  To withstand internal pressure from osmosis
• How do multicellular organisms increase their surface area for gas exchange?

  By developing specialized structures like lungs
• What is the significance of a large surface area to volume ratio in small animals?

  It aids in heat loss and gas exchange
• What is the effect of temperature on the kinetic energy of molecules?

  Higher temperature increases kinetic energy
• What is the relationship between concentration gradient and diffusion direction?

  Diffusion occurs down the concentration gradient
• What is the primary reason for the evolution of transport systems in large animals?

  To efficiently deliver oxygen and nutrients