biology paper 1 combined science Edexcel

• what happens during the interphase stage of the cell cycle?

  DNA duplicates
• what happens during the prophase stage of the cell cycle?

  • chromosomes condense
  • nucleus membrane breaks down
• what happens during the metaphase stage of the cell cycle?


  chromosomes line up in the middle of the cell
• what happens during the anaphase stage of the cell cycle?


  chromatids pulled to opposite ends of the cell
• what happens during the telophase stage of the cell cycle?


  new membranes form around each of the sets of chromosomes
• what happens during cytokinesis?


  cytoplasm and cell membrane divide to form two separate cells
• how do you convert millimetres to micrometers?

  x1000
• how do you convert millimetres to nanometres?

  x1000000
• how do you convert micrometers to picometres?

  x1000000
• how is micrometers written in standard form?

  x 10^-6 m
• how is nanometres written in standard form?

  x 10^-9 m
• how do you calculate image size of a specimen?


  magnification X real size
• what is mono hybrid inheritance


  inheritance of traits determine by single gene
• describe structure of nervous system

  stimulus - receptor - sensory neurone - CNS - motor neurone - effector - response
• what is the function of the receptor?

  to detect stimuli
• two examples of an effector


  Muscle, gland
• What happens when a stimulus is deters by receptors?


  information converted into electrical impulse, which is then sent along sensory neurones to CNS
• What happens when the impulse reaches the CNS


  impulses travel through CNS across relay neurones, and CNS coordinates response
• how does CNS send information To an effector ?

  Along a motor neurone
• What is reaction time

  Time it takes to respond to stimulis
• What is the difference between dendrons/dendrites and axons?


  Dendrites carry nerve impulses towards cell body, axons carry nerve impulses away from cell body
• What is the purpose of the myelin sheath?

  Acts as electrical insulator, speeding up electrical impulse
• How do long neurones speed up the impulse?


  Connecting with another neurone slows impulse down, so one long neurone much quicker than several short neurones
• One is the structure of a SENSORY neurone?

  long dendron, cell body (in middle of neurone), one short axon
• What so function of SENSORY neurone?


  to carry nerve impulses from the cell body to the CNS
• what is the structure of a MOTOR neurone?


  many short dendrites, long axon, cell body
• What is the FUNCTION of a motor neurone?

  Carry nerve impulses from CNS to effector cells
• What is structure of relay neurone?

  short dendrites, cell body, an axon
• What is function of relay neurone?


  To transmit signals between sensory and motor neurones.
• what is a synapse?


  the connection between two neurones
• how is a nerve signal transferred across a synapse?


  chemicals called neurotransmitters diffuse across the gap, these neurotransmitters then set off a new electrical impulse in next neurone
• what do carbohydrates do?


  break down carbohydrates into simple sugars (amylase breaks down starch into glucose)
• what does protease do?

  breaks down proteins into amino acids
• What does lipase do?


  Breaks down lipids into glycerol and fatty acids
• starch turns iodine from orange to black
• sugars turn Benedict’s solution from blue to orange
• protein turns biurets reagent from blue to purple
• lipids (fats) turn cold ethanol cloudy
• diffusion

  movement of particles from an area of high concentration to an area of low concentration down the concentration gradient. it is passive as it requires no energy
• osmosis

  the movement of water particles from an area of high water concentration to an area of low water concentration across a semi permeable membrane