Respiration of the plant seeds
Teacher Notes
BIOLOGY
Plant
Physiology
Applied Technology: Data-logging
Driving Question:
Do plant seeds respire?
Student Level: High School (15-18 )
Duration: 2 lesson period
Recommended Settings: Student Investigations
Learning Objectives
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To determine whether non-germinating and germinating seeds respire.
To compare the rates of cellular respiration of non-germinating and germinating
seeds.
To compare the rates of cellular respiration during a day and night.
Didactical Approach
In this activity non-germinating and germinating seeds are used to demonstrate plant
respiration. The carbon dioxide (CO2) gas sensor is used to monitor the concentration of
carbon dioxide in a sealed jar containing plant seeds. Both non-germinating and
germinating seeds are tested. Additional cellular respiration of germinating seeds is tested
in dark and in light.
The main experiment takes few hours (at least 2 hours) so this activity should be divided
into two lesson periods. First lesson is the preparation and setting up of the experiments
by students. The second lesson is analysing the measurement results.
Concepts learnt in this activity:
– Seeds respiration, rate of seeds respiration.
Materials
In your investigations you will use:
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Data-logger or interface e.g. CLAB,
CO2 gas sensor,
Temperature sensor,
Light sensor,
[optional] O2 gas sensor,
Seeds for example cuckoo-flower or peas,
Respiration of plant seeds – Teacher Notes
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– Paper towel or cotton,
– Big glass jar or large, transparent plastic bottle.
Procedure
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Together with your students prepare germinating seeds two-three days prior to the
experiment. This procedure is described in the Student sheet.
Provide student with germinating and non-germinating seeds and let them set up the
experiments.
Open Coach Activity ‘Respiration of plant seeds’.
Since the experiments are relatively long during the first lesson setup the
measurements and during the next lesson analyse the collected data and draw
conclusions.
Questions and Assignments
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Do non-germinating seeds undergo cellular respiration? What is evidence for this?
Do germinating seeds undergo cellular respiration? What is evidence for this?
Why do germinating seeds undergo cellular respiration?
Determine the rate of respiration of germinating seeds.
Investigate the rate of respiration of germinating seeds in dark and in ambient light
(circa 700 Lux).
Compare the rates of respiration in dark and light. Explain how the CO2 gas
concentration changes in dark and in light.
Do plants respire during the night? Do they respire during the day?
Data Analysis
Before experiments study with students the germinating and non-germinating seeds such
as cuckoo-flower seeds, beans or peas. Have a brief discussion about what’s going on
inside the seeds. Students may think the germinating seeds will photosynthesize, but note
that only the seed coat is green. These seeds are relying on the nutrients within the seed
itself to germinate and start photosynthesis.
An exemplary measurement performed with germinating cuckoo-flower seeds (3 boards
with 50 germinating seeds in the closed jar) is shown below. The measurement was
performed in daylight. The measurement data shows that germinating seeds produce the
CO2 gas. In the course of the experiment the rate of CO2 production becomes lower, the
respiration rate of germinating seeds decreases because there is not enough O2 gas in the
closed jar.
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CMA Learning and Teaching Resources
The dry seeds should not show any cellular respiration.
Students can conclude that germinating seeds (plants) respire by using oxygen and
producing carbon dioxide gas, they respire in the similar way as animals.
The result of the experiment performed in dark is similar; the resulting graph is a little bit
more flat. Such experiment show students that plants respire not only during a night but
also during a day.
Additionally by using the temperature sensor the
influence of temperature on the rate of
respiration can be investigated.
The change in oxygen concentration is very
small, about 0.5%. Measuring in parts per
million (ppm) yields more differentiated data.
However, the percentage measurement shows
a difference as well.
Instead of glass jar, the sampling bottle supplied
with the CO 2 sensor can be used.
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Resources
Coach Activity: Respiration of plant seeds.cma7
Copyright
Authors: CMA Team
© CMA
This work is licensed under a Creative Commons Licence:
Attribution-NonCommercial-ShareAlike CC BY-NC-SA
Respiration of plant seeds - Teacher Notes
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