2.39- practical: investigating respiration

• Background

  • We can investigate the production of carbon dioxide and heat from respiration through experiments using germinating seeds or other living organisms such as woodlice
• apparatus

  • Boiling tubes
  • Rubber bungs
  • Hydrogen carbonate indicator solution
  • Cotton wool
  • Glass beads
  • Germinating seeds
  • Boiled/dead seeds
• method

  • Measure out 10 cm3 of hydrogencarbonate indicator into 3 boiling tubes
  • Put in a layer of cotton wool
  • Place 10 germinating seeds in tube A
  • Place 10 boiled/dead seeds in tube B
  • Place 10 glass beads in tube C
  • Seal each tube with a rubber bung
  • After 3 hours, observe the colour of the indicator
• Hydrogencarbonate indicator

  • Hydrogencarbonate indicator is orange in atmospheric CO2 levels
  • In high CO2 levels the indicator absorbs the CO2 and becomes yellow
  • In low CO2 levels it loses CO2 and becomes purple
• Results

  • In this investigation, we would expect to note the following
  • Tube A should turn yellow as the seeds are respiringand producing carbon dioxide
  • Tube B should remain orange as the dead seedsproduce no carbon dioxide
  • Tube C should remain orange as there is no living material in there
• Practical investigation: demonstrating the production of heat

  Apparatus

  • Vacuum Flasks
  • Thermometer
  • Cotton wool
  • Germinating seeds
  • Dead/boiled seeds
• Practical investigation: demonstrating the production of heat: method

  • Set up the flasks as shown in the diagram
  • Flask A with the dead seeds
  • Flask B with the germinating seeds
  • Make sure the cotton wool is plugging the top of each flask
  • Hold the thermometer in place with the cotton wool
  • Invert the flask
  • Record the initial temperature
  • After 4 days, record the final temperature
• Practical investigation: demonstrating the production of heat- results

  • The thermometer in the flask with the germinating seeds(Flask B) should show an increase in temperature
  • Flask A should remain at room temperature
  • This is because the seeds in flask B are respiring and producing heat energy in the process
  • This shows that respiration is an exothermic reaction
  • The seeds in flask A are not respiring because they are dead, so the temperature remains the same
• CORMS 1st investigation

  • Change - We will change the content of the boiling tube (germinating seeds, dead seeds or glass beads)
  • Organisms - The seeds used should all be of the same age, size and species
  • Repeat - We will repeat the investigation several times to ensure our results are reliable
  • Measurement 1 - We will observe the change in the hydrogen carbonate indicator
  • Measurement 2 - ...after 3 hours
  • Same - We will control the volume of hydrogen carbonate indicator, the number of seeds/beads, the temperature of the environment
• CORMS 2 investigation

  • Change - We will change the content of the flasks (germinating seeds or dead seeds)
  • Organisms - The seeds used should all be of the same age, size and species
  • Repeat - We will repeat the investigation several times to ensure our results are reliable
  • Measurement 1 - We will observe the change in the temperature on the thermometer
  • Measurement 2 - ...after 4 days
  • Same - We will control the number of seeds, the starting temperature of the flasks, the material and size of the flasks