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

Practical investigation: demonstrating the production of carbon dioxide

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 CO_2?levels
• In?high CO_2?levels the indicator absorbs the CO_2?and becomes?yellow
• In?low CO₂?levels it loses CO₂?and becomes?purple

Colour results for hydrogen carbonate indicator

Results

• In this investigation, we would expect to note the following
  • Tube A?should turn?yellow?as the seeds are?respiring?and producing?carbon dioxide
  • Tube B?should remain?orange?as the?dead seeds?produce?no carbon dioxide
  • Tube C?should remain?orange?as there is?no living material?in there

   

Experiment to demonstrate the production of carbon dioxide by living material during respiration

Practical investigation: demonstrating the production of heat

Apparatus

• Vacuum Flasks
• Thermometer
• Cotton wool
• Germinating seeds
• Dead/boiled seeds

Method

• Set up the flasks as shown in the diagram
  • Flask A?with the?germinating seeds
  • Flask B?with the?dead 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

Experiment to demonstrate the production of heat by living material during respiration

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

Applying CORMS evaluation to practical work

• When working with practical investigations, remember to consider your CORMS evaluation

CORMS evaluation

• In the first investigation, your evaluation should look something like this:
  • 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

   

• For the second investigation, your evaluation should look something like this:
  • 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

轉載自savemyexams