======Measuring Oxygen Use by Germinating Seeds======


<WRAP right box>
**Materials: **{{$demo.materials_description}}\\
**Difficulty: **{{$demo.difficulty_description}}\\
**Safety: **{{$demo.safety_description}}\\
\\
**Categories:** {{$demo.categories}}
\\


**Alternative titles:** Seed Respiration with a Respirometer
</WRAP>

====Summary====                   
{{$demo.summary}}



====Procedure====  
  -Germinate seeds on moist paper towels one or two days before the lab.  
  -Insert a bent glass or plastic tube into a one-hole stopper so that the short end goes inside the test tube.  
  -Mark a line 0.5 cm from the bottom of a large test tube and fill to this mark with limewater.  
  -Place a small wad of moist cotton above the limewater and add about 1 g of germinating seeds on top of the cotton.  
  -Attach the stopper with tubing securely to make an airtight seal. Support the test tube upright with a stand or stacks of books.  
  -Tape a metric ruler to the tube, then add a small drop of liquid detergent into the tubing with a pipette. The drop should be visible near the open end.  
  -Wait about 5 minutes for the limewater to absorb any carbon dioxide already in the chamber.  
  -Record the position of the detergent drop as the initial reading.  
  -Take new readings every minute for 15 minutes, measuring movement of the drop along the ruler.  
  -Compare the distance moved to estimate oxygen consumption by the seeds.



====Links==== 
Respiration of Germinating Seeds - pascoscientific: 
{{youtube>3W9g4KBiKxU?}}\\

Experiment to show that Co2 is released during germination of seeds - Science Projects: 
{{youtube>q6QfMMXlzvE?}}\\

📄 Seed Respiration - Agri-science Resources for High School Sciences: [[https://www.biologyjunction.com/images/misc/respiration%20of%20germinating%20seeds.pdf]]\\

====Variations====
  *Use different seed types (beans, peas, corn) and compare respiration rates.  
  *Test at different temperatures (room temperature, cooler, or warmer conditions).  
  *Vary the amount of moisture in the cotton to see its effect.  
  *Compare healthy versus stressed seeds (e.g., partially dried or exposed to light).



====Safety Precautions====
  *If glass tubing is used, handle with care to avoid breakage; pre-bent glass is safer.  
  *Use gloves when handling limewater or calcium hydroxide paste, as it can irritate skin.  
  *Keep detergent and limewater away from eyes and mouth; wash hands after the experiment.  
  *Ensure the respirometer is stable and cannot tip over.




====Questions to Consider====
  *Why is limewater included in the respirometer? (It absorbs carbon dioxide so only oxygen consumption is measured.)  
  *What does the movement of the detergent drop indicate? (The seeds are consuming oxygen, creating a partial vacuum that pulls the drop inward.)  
  *How might seed size affect respiration rate? (Larger seeds may respire more overall, but smaller seeds may have higher respiration per gram.)  
  *What effect would temperature have on respiration rate? (Higher temperatures generally speed up respiration until enzymes are damaged.)  
  *Why are seeds actively respiring during germination? (They use stored food for energy to support growth before photosynthesis begins.)