Metabolic Pathways Take another paper cup and add enough lima beans to cover the
ID: 224584 • Letter: M
Question
Metabolic Pathways
Take another paper cup and add enough lima beans to cover the bottom of the cup. Add then grape juice to the cup (3/4 of the volume).
Cover it with plastic wrap
Leave the beans in solution for 24 hours.
After 24 hours write your observations
The purpose of this activity is to collect the products of cellular respiration in solution and measure them by a color change. The mitochondria in our beans will be activated when placed in solution and perform the reactions of cellular respiration. The sugars in the juice will nurture them to perform the pathway efficiently.
OBSERVATIONS.
Describe your observations below (Is there any change in the color of the juice now? How can you explain this? Please review the equation for cellular respiration above and try to find a link between the bean and the carbonate mediated change).
Explanation / Answer
There will be no colour change until and unless you add a pH sensitive dye in the solution, for eg., bromophenol blue.
The equation for cellular respiration goes as under:-
glucose + oxygen ---> carbon dioxide + water
The carbon dioxide so formed combines with water to form carbonic acid nd exits as bicarbonate ions (HCO3-) in aqueous solutions which results in increased acidity, i.e the pH falls drastically. Bromophenol blue is blue in colour normally(pH = 4.6) but in acidic conditions turns yellow and then green (with increased acidity) due to reduction.
The link between the bean and the carbonate mediated change is that the CO2 producted due to celular respiration in the mitochondria of the beans will results acidification of the solution as would happen when you would directly add carbonate ions. This would result in a blue to green/yellow ransition of the color of the solution (provided bromophenol blue is added).