Rate of Respiration in Yeast

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Rate of Respiration in Yeast

Aim: I am going to investigate the rate of respiration of yeast cells

in the presence of two different sugar solutions: glucose, sucrose. I

will examine the two solutions seeing which one makes the yeast

respire faster. I will be able to tell which sugar solution is faster

at making the yeast respire by counting the number of bubbles passed

through 20cm of water after the yeast and glucose solutions have been

mixed.

Prediction: I predict that the glucose solution will provide the yeast

with a better medium by which it will produce a faster rate of

respiration. This is because glucose is the simplest type of

carbohydrate (monosaccharide). However sucrose is a complex sugar it

contains large molecules making it a disaccharide.

Due to the large molecules being saturated and the small molecules

being unsaturated this will allow the glucose to mix easily with the

yeast therefore making it respire more frequently. The sucrose sugar

however having larger molecules will find it harder to mix in with the

yeast; this will make the rate of respiration in the sucrose much

slower as it is not as efficient as the glucose.

Yeast requires enzymes to digest the food on which the yeast is

living. The enzymes digest the food the yeast is living on (normally

sugars such as Glucose and Sucrose) breaking down the large molecules

into smaller ones. It takes longer to break down the large molecules

rather than the smaller molecules. This means that the yeast does not

need to do any work when provided with small molecule foods such as

glucose. The small molecule foods allow the yeast to respire easily.

By already h...

... middle of paper ...

... improved in any way unless another sugar was utilized.

There were some things that were difficult to keep constant in the

experiment and this is where my results may have wavered slightly. It

was difficult to keep the temperature of the warm water constant as it

dipped at times which could have had an effect on how efficient the

enzymes were. The delivery tubes were becoming blocked sometimes and

by shaking the test tube it cleared them. However as we shook the test

tube a large number of bubbles were formed which may not have formed

if we didn't shake the test tube. Also we might have been shaking the

test tubes at different speed which may have caused a greater number

of bubbles to be released.

Overall I felt that the experiment was accurate and reliable and there

was not much that could have been changed on it.

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