bio paper 1 required practicals

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

  Describe how to use an optical microscope
• Why is it important to learn the details of using an optical microscope?

  It could come up in a six mark essay
• What is the main part of the optical microscope where the slide is placed?

  The stage
• What is the function of the lamp in an optical microscope?

  It illuminates the slide from below
• What do some optical microscopes use instead of a lamp?

  A mirror to reflect light
• 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 times, ten times, or 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 should you do after placing the slide on the stage?

  Use clips to hold the slide in place
• How do you position the objective lens before viewing the slide?

  Turn the coarse focusing dial slowly
• Which objective lens should you select first for viewing?

  The lowest power objective lens
• Why should you look at the microscope from the side while adjusting the lens?

  To avoid damaging the slide
• What should you do after the objective lens is almost touching the slide?

  Look down through the eyepiece
• What do you do to bring the cells into focus after looking through the eyepiece?

  Use the fine focusing dial
• How do you calculate the total magnification of the microscope?

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

  $40 \text{ times}$
• What should you do after selecting a higher power objective lens?

  Adjust the fine focusing dial again
• What can you see when looking at animal cells under the microscope?

  Nucleus, cytoplasm, and cell membrane
• What might you see when looking at plant cells under the microscope?

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

  Vacuole and chloroplasts
• How do you include a magnification scale in your drawing?

  Measure the diameter of the field of view
• What should you do with the ruler when measuring the field of view?

  Place it over the stage
• What should you include in your drawing besides the cells?

  A magnification scale
• What is the purpose of the vision workbook mentioned in the video?

  To gather questions on the practical
• What should you be able to describe by the end of the video?

  Investigate the effect of osmosis on plant tissue
• What is osmosis?

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

  Water moves into the cell, causing expansion
• What occurs when a plant cell is placed in a concentrated solution?

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

  Potato
• Why do we peel the potato before the experiment?

  The skin can affect osmosis
• What tool is used to produce potato cylinders?

  Cork board
• Why do we trim the potato cylinders to the same length?

  To ensure consistent measurement of osmosis
• What is a good length for the potato cylinders?

  Three centimeters
• What do we measure before placing the potato cylinders in the solution?

  The length and mass of each cylinder
• How much of a 0.5 molar sugar solution is added to the first test tube?

  10 centimeters cubed
• Why do we use distilled water instead of tap water?

  Distilled water contains no dissolved substances
• What should we do after leaving the potato cylinders overnight?

  Gently roll them on paper towel