Aerobic Respiration IAA

[Inquisitive Stone]

Ok so those of you familiar with the edexcel GCSE exam board, we have to do these assessed practicals, and the one I'm going to do in biology is apparently one that has never worked, in all the years that it has been around apparently even the exam board couldn't make it work when they went on a conference in Malaysia. The experiment is as described below:

 

The aim of the experiment is to find out how temperature affects aerobic respiration.

So the method in which we are going to test this will be using mealworms (the exam boards idea). Basically we are going to take the mealworms and place them into different beakers. So basically I think it would be about 5 meal worms to a beaker.

Then we would place the beakers in several water baths ranging from 10degrees to maybe 80degrees, depends on how many we can get (at 10degree intervals).

The idea then is to measure the amount of respiration by sealing up the beaker. Then inserting capillary tubes into the sealed beaker. The capillary tubes were preprepared with ink in them so that we can measure the rate of respiration in each of the beakers.

Okay so assuming that 40degrees is the optimum temperature, then the ink in the capillary tube for the beaker will have moved the most.

But for some reason it doesn't work. (The exam board decided to stick with this dumb experiment even after THEY tested it and still failed.

 

So does anyone have any clues on what went wrong, any thoughts?

[Greippi]

I did this exact experiment for AS level biology 7 years ago. It worked. It worked very well.

 

My thought is that the equipment used wasn't good enough. You have to make sure that you have a good enough seal so that no air can escape AT ALL.

 

I can't remember the exact apparatus we used though - I think it was something smaller than a 50ml beaker (and a muslin bag was involved somewhere), and used more than 5 worms - possibly we used boiling tubes. The experiment was left for quite a while too - at least 3 hours, maybe over night.

[Inquisitive Stone]

I see...

Thanks for the advice.

[John Cuthber]

I can see a couple of problems, part of the oxygen used up is replaced by an equal volume of CO2, so the change in volume won't be as big as you expect.

Also I wonder if, like termites and people (among others) mealworms produce methane.

 

Also, of course, without a perfect seal, this simply won't work.