AS- due 12/11/24

• Explain how the structure of starch relates to its function (4 marks)

  It is insoluble and therefore does not affect the rate potential of the cell, so water isn't drawn in via osmosis

  It is large and insoluble so doesn't diffuse out of cells

  It is compact, so a lot of it can fit into a small space

  When hydrolysed it forms alpha glucose which is both easily transported and readily used in respiration
• Describe the test for reducing sugars

  Benedicts solution

  1. Add the Benedict's solution to a sample solution in a test tube
  2. Heat the test tube gently in a water bath that has been brought to boil for a few minutes
  3. If a reducing sugar us present, a coloured precipitate will form as copper (II) sulphate is reduced to copper (I) dioxide which is insoluble in water
• Which kinds of bonds would you find between the following monomers

  glucose- glycosidic

  glycerol+fatty acids- ester bonds

  amino acids- peptide bonds
• Give the equation used to calculate magnification

  magnification=size of image/ size of real object
• Explain why cells must be placed in a cold, buffered, isotonic solution

  Keeping the solution cold reduces enzyme activity and therefore slows any chemical reactions within the cell. Buffered maintains the pH of the cell to avoid the pH from becoming too low and denaturing the enzymes. Keeping the solution isotonic prevents water from moving into sub cellular structures via osmosis in order to stop them from bursting and shrivelling
• Describe the function of the following organelles

  1. ribosomes- protein synthesis
  2. RER- provides a large surface area for the synthesis of proteins and glycoproteins, they also provide a pathway for the transport of material (especially proteins) throughout the cell.
  3. mitochondria- the site of aerobic respiration within a cell and are responsible for the production of ATP
• Describe the events of prophase

  This is where the chromosomes first become visible as long, thin threads.

  The centrioles move to the poles if the cell

  From these, spindle fibres develop and span the cell from pole to pole. This is collectively called the spindle apparatus

  The nucleolus disappears and the nuclear envelope breaks down, leaving chromosomes free in the cytoplasm

  They are drawn to the middle of the cell by the spindle fibres
• Name the 3 stages of the cell cycle

  Prophase

  Metaphase

  Anaphase