biology

• What should you be able to describe by the end of the video?

  Causes and symptoms of infectious diseases
• Where can students find questions on plant diseases?

  In the vision workbook
• What is the main focus of the video?

  Diagnosing diseases in plants
• What is osmosis?

  Diffusion of water through a membrane
• What is the direction of water movement in osmosis?

  From dilute solution to concentrated solution
• What type of membrane allows osmosis to occur?

  Partially permeable membrane
• What does a dilute sugar solution contain a lot of?

  Water molecules
• What do scientists say about dilute solutions?

  They contain a high concentration of water
• What does a concentrated sugar solution contain a lot of?

  Sugar molecules
• What happens to water molecules in a concentrated solution?

  They are present in low concentration
• What does a partially permeable membrane allow?

  Some molecules to pass through
• What happens to water when a cell is placed in water?

  Water moves into the cell by osmosis
• What effect does osmosis have on an animal cell in water?

  The cell expands and may burst
• What happens to an animal cell in a concentrated solution?

  Water moves out, causing the cell to shrink
• What happens to a plant cell when placed in water?

  Water moves in, causing the cell to expand
• Why doesn't a plant cell burst when it expands in water?

  The cell wall prevents bursting
• What term describes a swollen plant cell?

  Turgid
• What happens to a plant cell in a concentrated solution?

  Water moves out, causing the cell to shrink
• What term describes a shrunk plant cell?

  Flaccid
• What are the effects of osmosis on animal and plant cells?

  • Animal cells in water: expand and may burst
  • Animal cells in concentrated solution: shrink
  • Plant cells in water: expand and become turgid
  • Plant cells in concentrated solution: shrink and become flaccid
• What is the relationship between osmosis and cell concentration?

  • Osmosis moves water from dilute to concentrated solutions
  • Affects both animal and plant cells differently
• What is diffusion?

  The spreading out of particles
• What does the term "net movement" mean in diffusion?

  Overall movement from high to low concentration
• What are three molecules that move in and out of cells by diffusion?

  • Oxygen
  • Carbon dioxide
  • Urea
• Why do cells need oxygen?

  For respiration carried out by mitochondria
• How does the concentration of oxygen outside the cell compare to inside?

  Higher concentration outside than inside
• What happens to oxygen molecules during diffusion?

  They move into the cell from outside
• What is produced as a waste gas during respiration?

  Carbon dioxide
• How does the concentration of carbon dioxide inside the cell compare to outside?

  Higher concentration inside than outside
• What happens to carbon dioxide during diffusion?

  It moves out of the cell into the environment
• What is urea and how does it move out of cells?

  It is a waste product that diffuses into blood plasma
• What are the three main factors that affect the rate of diffusion?

  1. Difference in concentrations (concentration gradient)
  2. Temperature
  3. Surface area of the membrane
• What is the effect of a greater concentration gradient on diffusion?

  It increases the rate of diffusion
• How does temperature affect the rate of diffusion?

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

  It allows more molecules to pass through
• What is the relationship between surface area and rate of diffusion?

  Larger surface area increases the rate
• What should you be able to describe by the end of the video?

  • The meaning of diffusion
  • Factors affecting the rate of diffusion
• What process allows substances to be absorbed against a concentration gradient?

  Active transport
• How does active transport differ from diffusion?

  Active transport moves substances against the gradient
• What is the energy source for active transport?

  Energy from respiration