Bio paper 1 (required practicals)

• What is the main part of the optical microscope where the slide is placed?

  The stage
• What is the purpose of the clips on the stage?

  To hold the slide in place
• What is located below the stage of an optical microscope?

  A lamp or mirror
• How does light pass through the microscope slide?

  It passes up through the slide
• What are the lenses above the stage called?

  Objective lenses
• How many objective lenses do most microscopes have?

  Three different objective lenses
• What are the typical magnifications of the objective lenses?

  Four, ten, and forty times
• What is the magnification of the eyepiece lens?

  Ten times
• What are the two focusing dials on the microscope?

  Coarse and fine focusing dials
• What is the first step to view a prepared slide using an optical microscope?

  Place the slide onto the stage
• What is osmosis?

  Diffusion of water through a membrane
• What happens to plant cells in water?

  Water moves in, causing cells to expand
• Which objective lens should be selected first?

  The lowest power objective lens
• How do you position the objective lens before viewing the slide?

  Turn the coarse focusing dial slowly
• Why should you look at the microscope from the side while adjusting?

  To avoid damaging the slide
• What occurs when plant cells are placed in a concentrated solution?

  Water moves out, causing cells to shrink
• What vegetable is commonly used to investigate osmosis?

  Potato
• What tool is used to produce potato cylinders?

  Cork board
• What should you do after the objective lens almost touches the slide?

  Stop turning the dial
• Why do we peel the potato before the experiment?

  The skin can affect osmosis
• What do you do after looking through the eyepiece?

  Turn the coarse focusing dial
• Why is it important to use cylinders of the same diameter?

  To ensure consistent osmosis results
• What length should the potato cylinders be trimmed to?

  About three centimeters
• How do you calculate total magnification?

  Multiply eyepiece by objective magnification
• What is the total magnification when using a ten times eyepiece and a four times objective lens?

  $40 \text{ times}$
• What is the first step after preparing the potato cylinders?

  Measure the length and mass of each cylinder
• What volume of sugar solution is added to the first test tube?

  10 centimeters cubed
• What should you do after calculating total magnification?

  Select a higher power objective lens
• What concentration of sugar solution is used in the first test tube?

  0.5 molar
• Why is distilled water used instead of tap water?

  It contains no dissolved substances
• What should you see when looking at animal cells?

  Nucleus, cytoplasm, and cell membrane
• What can you see in plant cells under a light microscope?

  Cell wall, cytoplasm, and nucleus
• What additional structures might be visible in plant cells?

  Vacuole and chloroplasts
• What should be done after leaving the potato cylinders overnight?

  Gently roll them on paper towel
• What should be included in your drawing of cells viewed under a microscope?

  • Clear labeled drawing of cells
  • Magnification scale
  • Diameter of field of view in mm
• Why is it important not to press on the cylinders when drying them?

  To avoid forcing water out of cells
• How do you create a magnification scale for your drawing?

  Measure the diameter of the field of view
• What should you write on your drawing regarding magnification?

  The magnification used
• What must be measured again after drying the potato cylinders?

  Length and mass of the cylinders
• What resources can help with questions on this practical?

  • Vision workbook
  • Online resources
  • Class notes