Cells and transport

• What is diffusion?

  The movement of a substance from an area of high concentration to an area of low concentration
• What is osmosis?


  The diffusion of water molecules from a region of higher concentration to a region of lower concentration through a partially permeable membrane
• What is active transport?

  The movement of molecules across a cell membrane using energy from respiration (ATP), against a concentration gradient
• How does active transport differ from diffusion and osmosis?

  Active transport requires energy and moves substances against a concentration gradient
• What are the three methods of substance movement into and out of cells?

  Diffusion, osmosis, and active transport
• How does surface area to volume ratio affect the rate of movement of substances into and out of cells?

  A greater surface area increases the rate of movement of substances
• What effect does temperature have on the movement of substances into and out of cells?

  Higher temperature increases the kinetic energy of particles, leading to faster movement
• How does an increase in concentration gradient affect the rate of movement of substances?

  A stronger concentration gradient increases the rate of movement of substances
• What practical methods can be used to investigate diffusion and osmosis?

  • For diffusion:
  • Non-living system: Beaker of water
  • Living system: Plant cell or animal cell
  • For osmosis:
  • Non-living system: Beaker of water with a selectively permeable membrane
  • Living system: Plant cell or animal cell in a solution of different concentrations
• What are the main structures of a cell?

  Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes, cell wall, chloroplast, and vacuole
• What is the function of the nucleus in a cell?

  It contains genetic material and controls the activity of the cell
• What role does the cytoplasm play in a cell?

  Most chemical processes take place here, carried out by enzymes
• How does the cell membrane function?

  It controls the movement of substances into and out of the cell
• What is the primary function of mitochondria?

  Most energy is released from respiration here
• What is the role of ribosomes in a cell?

  Protein synthesis happens here
• What is the function of the cell wall?

  It strengthens the cell
• What is the role of chloroplasts in plant cells?

  It contains chlorophyll, which absorbs light energy for photosynthesis
• What is the function of the vacuole in plant cells?

  It is filled with cell sap to help keep the cell turgid
• What structures do animal cells have compared to plant cells?

  Animal cells have just a nucleus, cytoplasm, cell membrane, and mitochondria

  
• What additional structures do plant cells have compared to animal cells?

  Plant cells have a vacuole, cell wall, and chloroplast

  
• What are the levels of organization in living organisms?

  • Organelles: tiny structures performing specific functions (e.g., chloroplasts, mitochondria)
  • Cells: building blocks of life (e.g., nerve cell, red blood cell)
  • Tissues: groups of similar cells working together (e.g., muscle tissue)
  • Organs: groups of different tissues working together (e.g., heart, liver)
  • Organ systems: groups of different organs working together (e.g., digestive system)
• Why is cell differentiation important?

  It allows cells to specialize and perform specific functions in an organism
• What are the advantages of using stem cells in medicine?

  Advantages:

  • Replaces faulty cells with healthy cells
  • Embryonic stem cells are easy to extract from embryos
• What are the disadvantages of using stem cells in medicine?

  Disadvantages:

  • Embryo destroyed when cells are removed
  • May produce cancer cells instead of healthy cells