Exam questions.

• Prokaryotic cell

  Contains: Plasmids, Cytoplasm

  Doesn’t contain a nucleus
• Eukaryotic cell 


  Contains a nucleus and cytoplasm

  Doesn’t contain plasmids
• What is this cell?

  Bacteria cell

  
• What is the function of ribosomes?


  Make proteins (enzymes)
• 1.5 micrometers into millimetres


  0.0015mm
• Why does a 1.5 (um) bacteria cells not contain mitochondria 8 (um)?

  Mitochondria are bigger then bacteria
• A cell divides every 30 minutes. If there was one cell at the start, how many is there after 2 hours?

  16
• Describe the changes in the number of alive cells shown in the graph above in the first 20 hours

  the number of bacteria stays the same until 11 hours then increases rapidly from 11 to 14.5 hours then it stays the same from 15 to 20.5 hours

  
• suggest one reason cells decreased after 20 hours?

  • lack of food / nutrients / oxygen / space
  • build up of toxins
  • temperature too high
• cell membrane

  controls the movement of substances into and out of the cell
• mitochondria

  where most energy is released in respiration
• Nucleus 


  controls the activities of the cell
• What organelles are only found in plant cells?

  • chloroplasts
  • vacuole
  • cell wall
• What is A and B?

  • A = nucleus
  • B = cell membrane

  
• why do human skin cells need to divide?

  Repair/ growth or to replace cells
• human stem cells may come from 


  embryos
• human stem cells can be used to treat


  paralysis
• describe the function of the muscle cells in the wall of the stomach


  contract to churn food
• what is the function of mitochondria?


  to transfer for use by (aerobic) respiration or from glucose
• what is the function of ribosomes?

  to make protein / enzymes
• Why can’t ribosomes be seen through a light microscope?

  too small
• Body cells go through division. This is called

  mitosis
• What type of microscope is needed to see ribosomes and mitochondria?

  Electron microscope
• What is the advantage of using a electron microscope?

  Higher magnification
• equation for magnification 


  real size = image size / magnification
• A red blood cell is 8(um) in diameter, a bacteria cell is 40x smaller. What is the diameter of the bacteria cell?

  0.2(um)
• Root hair cells take up water from the soil. How are they adapted to do this?

  large surface area for faster osmosis or thin cell walls for shorter diffusion distance
• Why is the mean rate of water uptake higher on a hot day rather than a cold day?

  on a hot day more water is lost so more evaporation so more water uptake to replace water loss.
• Why do root hair cells contain mitochondria?

  respiration occurs in mitochondria, they release energy used for active transport.