INTRODUCTION
Cellular respiration is a process of food molecules oxidation to produce energy in ATP form; it includes aerobic and aerobic respiration. An aerobic respiration occurs in the presence of oxygen and the oxygen act as a nal electron acceptor. acceptor. An anaerobic respiration is i s also known as a s a fermentation process, which occurs in the absence of oxygen that uses an organic molecule as a nal electron acceptor. n the yeast cells, cell s, the fermentation process produces ! ATP, carbon dioxide and the wasteful product, ethanol. "uring this process, #A"$ will donate the atom hydrogen to keep generating c f #A"% and continue the fermentation process.
OBJECTIVE(S)
•
•
To To identify the type of cell respiration respiration in the yeast.
To To interpret the the results on yeast yeast reaction by using using blue methylene as the articial hydrogen acceptor.
APPARATUS & MATERIALS
Test Test tubes
&easuring cylinder
'eaker !() cm
Paralm
'lue methylene ).( *
+resh yeast )* % -lucose *
ater bath /012c 3 4!2c5
METHODOLOGY
. Test tubes was labelled A, ' and C. 3
!. )
cm
of fresh yeast was poured into the test tubes.
0. Test tube C was placed in a beaker of boiling water for 6e minutes. 4. ) drops of blue methylene was dropped into each of the test tube and were shake well. (. All the test tubes were placed in water bath for fteen minutes. The colour in each of the test tube was recorded. 7. Test tube ' was placed into a beaker of boiling water for 6e minutes. 8. A rubber stopper was inserted into each test tube and the test tubes were well shake. The colour change was recorded in each of the test tube. 1. The rubber stopper was remo6ed and the test tubes were placed in the water bath for fteen minutes. The colour change in each of the test tubes was recorded.
RESULTS Table 3.1 Yea!" #ea$"%'
Te!" "be
Te $l# b!e#*e+ ,
Y
-
A
Colour change from blue to white
hite to greenish blue
Precipitate formed /white5
B
Colour change from blue to white
+rom white to tur9uoise
+rom white to tur9uoise
C
:emain blue
+rom blue to tur9uoise
+rom blue to tur9uoise
UESTIONS & ANS/ERS 1. E0la%' "e b%$e2%$al #$e!! "a" ae'e+ %' "e "e!" "be! ba!e+ ' # b!e#*a"%'. Test tube A and ' change to colourless because of respiration and test tube C did not turn to colourless because the yeast is dead. Test tube C was placed in the water bath of boiling water. After shaking test tube A the tube turns to blue again because of reoxygenating the methylene blue.
4. De! "%! #ea$"%' $'"#lle+ b e'52e6 G%*e # #ea!'. es. 'ecause many aspects of fermentation re9uire en
3. G%*e 'e e0a2le 7 !"#$"#e # !b!"a'$e %' l%*%'8 $ell "a" %! #e#e!e'"e+ b ble 2e"le'e. #ucleus.
9. Na2e "e #$e!! "a" %'*l*e! "e a$"%*%" +e2'!"#a"e+ %' "%! e0e#%2e'". +ermentation.
DISCUSSION The purpose of this lab was to identify the type of cell respiration and to interpret the results on yeast reaction by using blue methylene as the
articial hydrogen acceptor. The result was determined by obser6ing the colour changes using blue methylene. +irstly, we poured ) ml of fresh yeast into each of test tube that labelled A, ' and C. The test tubes C were boiled for ( minutes and was well shake. Then, we add methylene blue into each of the test tube and put in a water bath /01
° C − 42 ° C ¿
for (
minutes. The colour changes that we obser6ed in test tube A is from blue to white. "espite, the colour changes in test tube ' is from blue to white and test tube C remain blue. Test tube A and ' ob6iously turns white colour because of respiration. Test tube C doesn=t change and remains blue because yeast cannot be ha6ing an e>ect as the boiling would kill it, so it must be function of the heat in6ol6ed in boiling. Then, the experiment was continued by placing the test tube ' in a beaker of boiling water for ( minutes and then co6ered by paralm into each of test tube and shake it. e obser6ed that the colour changes in test tube a change from white to greenish blue. n test tube ', the colour change from white to tur9uoise and test tube C change from blue to tur9uoise. Test tube A turn to greenish blue because of reoxygenating the methylene blue. hile test tube ' change from white to tur9uoise. t may be reoxidising. Then test tube C change from blue to tur9uoise. Then, the paralm were remo6ed and the test tube was placed in the water bath again for ( minutes. e obser6ed that the colour changes in test tube A were changes into white precipitate. hile, test tube ' remain unchanged and test tube C remain unchanged too. e obser6ed that many parallax error that e>ect on the result. +or the precautions, the test tube must be shaking carefully. "espite, the time taken must be precise, when we measure the 6olume of substances, the eye must be perpendicular to get an accurate result.
CONCLUSION n conclusion, the data supported the hypothesis. e can conclude that, the type of cell respiration in the yeast was identied and the results on yeast reaction by using blue methylene as the articial hydrogen acceptor was intrepret.Although there is a lot of inaccuracy between the steps, the results can be determined. ?ome impro6ements can be made to this procedure and experiments such as use more professional e9uipment such as electrical stirrer or any ad6ance stirrer. @ther than that, we can impro6e this experiment by increasing the 9uantity of water bath e9uipment. #ext, with the aid of rubber stopper we can shake the test tube better than using the paralm.
RE:ERENCE (S)
I'"e#'e"
www.whitelabs.comlesBn
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'iology ?olomon Dth edition
