warm germinating seeds

When seeds germinate they use energy and give off heat. To test this, you can use temperature sensors which will continuously monitor any heat produced.

You will set up some seeds in an insulated flask, and monitor their temperatures. The sensors can record very small temperature changes, often enough to yield results in a fairly short period of time.
You’ll need to wash the seeds in ‘Hypochlorite’ solution to kill any fungal spores that can also produce heat. You will also need a control experiment – a batch of seeds which have been killed by boiling.

What you need
Two vacuum flasks, cotton wool, germinating pea seeds, hypochlorite solution, Bunsen burner, mat and gauze, data logging interface, temperature sensors.

Connect the two temperature sensors to the interface.
Soak the pea seeds in Hypochlorite solution for 15 minutes to kill off fungal spores. Divide the batch of pea seeds into two parts. Boil one part for 10 minutes to kill the seeds. Allow them to cool. Set up the two vacuum flasks with the batches of pea seeds. Put a temperature probe each and add a cotton wool plug. If the sensors are adjustable, use a suitable range such as -10-40 degrees.
Start your sensing software. It may recognise the sensors you attach. Set up sensing software to record for 60 minutes.

Questions

• Did the control show any temperature change?
• What does the graph tell you about heat and germination?
• What does the shape of the graph tell you about the progress of the germination?
• If you recorded for twice as long how would the graph look?
• Teacher question
• How does having a graphical record, as opposed to temperature readings, affect pupils understanding of this experiment?