Student research results

Our AP Biology class recently investigated cellular respiration rates in various comparisons.  The student-designed experiments all produced results worth discussing.

Green Peas vs Chickpeas
       (Sofia Castro, Kiara Gilardi, Sharon Lampreda, Kate Menefee and Mansi Patel)
In this lab, we tested the cellular respiration of chickpeas and green peas, to observe how much oxygen they used.  We hypothesized that the green peas would
consume more oxygen than the chickpeas, because they had a thinner outer layer, so it would be easier to take in oxygen.  The results demonstrate that our hypothesis was correct.

Peas vs chickpeas

Warm Crickets vs Cold                 (Jesus Garcia, Jack Gerstenberg, Shirley Liu, Emily Orr and Daniel Valenzuela)
Our lab tested the effect of icewater and room temperature water on the respiration rate of crickets.  We found that over the course of twenty minutes,
the respiration rate of the crickets in room temperature water continued steady, whereas the crickets in icewater spiked up, leveled off, then decreased. 
We believe this happened because crickets are cold-blooded, and so they are strongly affected by the temperature of their surroundings.  We believe the icewater crickets
could sense the water was getting colder, so they started to respire more because they were in crisis mode.  Once the water got down to a certain temperature,
they stopped respiring, and then their respiration rate began to decrease.  The cold temperature caused slower chemical reactions in their mitochondria, resulting in less respiration.  

Warm vs cold crickets

Crickets vs Green Peas (Chloe Emerson, Patrick Martinez, Mina Shabhaz and Victor Torres)
In our experiment, we tested the respiration rate of both crickets and peas.  Over the course of twenty minutes, we found that crickets did respire more than the peas. 
We used a specific mass of crickets, and matched the mass of peas to the crickets.  Then, both subjects were submerged in water while in respirometer tubes,
and their oxygen consumption was measured.  We believe that the crickets respired more because they were insects (which are expected to be more active
than germinating seeds), and were experiencing an increased degree of stress.

Peas vs crickets

Amount of KOH reagent (Alyssa Catalan, Marcela Garcia, Christian McEntire, Elena Mendoza, and Krysta Valdez)  In our experiment, we estimated
the amount of cellular respiration of germinating peas by measuring oxygen consumption.  Since respiration produces the same volume of carbon dioxide gas
as it consumes in oxygen, we added KOH.  This is potassium hydroxide, a substance that converts CO2 from a gas into a solid.  This creates a lower pressure
inside the tube as oxygen is consumed, drawing water into the tube in a visible, measurable way.  Our results showed that 20 drops of KOH was the
maximum amount needed.  When we added 40 drops, the amount of volume change did not make much of a significant difference, changing by only .01 ml. 
The tube with no KOH actually pushed water out, because there was nothing to change the carbon dioxide to a solid compound to be removed. 
The other tubes in comparison pulled water into the tube.

KOH amount

Light vs Dark         (Julian Arrechavala, Ashley Goshay, Arzan Kermani, Ozzy Lara, and Ally Meza)    
Our group assumed that the amount of oxygen consumed would be greater in the tube of peas that were in the light, rather than the tube in the dark.  This was wrong,
as we now understand that the peas in the dark consumed the same amount of oxygen as the ones in the light.  Both tubes engaged in similar cellular respiration. 
In the light container, light energy activated the chloroplasts in the peas, leading to the reactions of photosynthesis.  So the peas in the light were producing some oxygen
in the cells, reducing their need for oxygen from the air.  This in turn reduced the water intake, which is shown on the graph as "oxygen consumption". 
Oxygen consumption was estimated by measuring water intake into the respirometers, but in our case we believe that both sets of peas consumed the same amount.   
In contrast, the peas in the dark were not activated by light, so no photosynthesis took place, and the peas took all their oxygen directly from the air in the tube. 
They had no internal source of oxygen, and this led to a steeper slope on the graph for the dark tube, compared to the light tube.     

Light vs dark

Ambient Light vs Intense Light
                        (Sarah Haugen, Alyssa Ines, Lily Miller and Hayley Stevenson)

Ambient vs intense

Back to AP biology page