exam questions

• describe and explain the changes in the level of radioactivity in the rough endoplasmic reticulum

  level of radioactivity decreases

  because the protein is moving out of the RER
• explain the shape of the curve for the secretory vesicles

  there were no secretory vesicles which is why there were low levels of radioactivity

  radioactive proteins have not yet reached the vesicles

  proteins have yet to pass to golgi
• compare and contrast the ultrastructures of eukaryotic cells and prokaryotic cells

  they both have a cell membrane

  they both contain ribosomes

  the DNA in E is membrane bound but the DNA in P is not

  the ribosomes in E are larger (80S) than ribosomes in P (70S)
• state one difference between DNA in cells (bacteria/prokaryote) and DNA present in lymphocytes (eukaryote)

  DNA in bacteria are not in the nucleus
• state the function of the structure labelled R (nucleolus)

  synthesis of ribosomes
• suggest why the structures of two of the same type of organelle look different in a photograph

  viewed from different angle

  when the cell was sliced
• describe the function of this organelle

  centrioles organise spindle fibres in cell division

  to separate chromosomes
• explain how the structures of amylopectin and glycogen make them suitable for storing energy

  branched therefore can be rapidly hydrolysed to release glucose

  compact so more energy can be stored

  insoluble therefore does not affect osmosis
• explain the relationship between the composition of the starch and the rate of hydrolysis by enzymes

  as amylose content increases the percentage of starch hydrolysed decreases

  amylose is unbranched and amylopectin is branched

  the less amylose present the greater the proportion of amylopectin

  branches increases the rate of hydrolysis
• calculate the ratio of amylose to amylopectin in cassava (amylose = 20.0%) give your answer in the simplest form

  100 - 20 = 80

  20:80 = 1:4
• describe the arrangement of glucose monomers in a cellulose molecule.

  monomers are connected by 1-4 glycosidic links

  alternate monomers are inverted