H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 6: Investigative Project
Assignment 6C + D: Undertake the project, collecting,
analysing, and presenting the results; review the
investigative project using correct scientific principles
Concentration of sugar in ripening bananas
Abstract
The overall aim of this practical investigation is to determine whether the
ripeness of bananas varies glucose content. The hypothesis for this investigation
is that as a banana’s ripeness increases, the sugar concentration will increase.
The results were produced by making a serial dilution of glucose and by
measuring the absorbance of banana samples using a colorimeter. The
absorbance readings of the banana samples were used with a calibration curve
of glucose to identify the glucose content of the banana samples. The overall
results showed that as the ripeness of the banana samples increased, so did the
content of glucose in the banana which was the hypothesis made prior to the
experiment. In terms of statistical significance, a statistical T-test was carried out
in addition to standard deviation which displayed that the results produced were
found to be statistically significant. This meant that the null hypothesis could be
rejected, and the alternative could be accepted- as a banana's ripeness
increases, the sugar concentration will increase. An overall conclusion was made
from the results along with the statistical tests performed- the ripeness of
bananas does vary glucose content as in bananas with a high degree of ripeness,
the glucose concentration is higher comparison to bananas with a lower degree
of ripeness.
Hypothesis
Hypothesis: As a banana's ripeness increases, the sugar concentration will
increase.
Null hypothesis: As a banana's ripeness increases, the sugar concentration will
stay the same.
Variables
Independent variable: Degree of ripeness based on colour and days of ripening
Dependent variable: Concentration of sugar in the bananas using colorimetry
and glucose calibration curve
Control variables: Type of banana (used bananas from same bunch), the mass of
the banana (measured using scale), the temperature
kept in (stored at room temperature)
Background
An experiment conducted by Al-bio (1) showed that the riper the banana, the
sweeter it is since a large proportion of starch is converted into sugars during the
ripening process. This increases the concentration of sugar in ripened bananas.
1
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 6: Investigative Project
Therefore, the higher the degree of ripeness of bananas, the greater the
concentration of sugar in bananas.
Another experiment was carried out on the sugar concentration in bananas and
this experiment included a hypothesis backed up by scientific knowledge (2).
This source explained how the content of sugars in bananas is highest for the
ripest bananas, e.g., yellow bananas, due to the lower content of starch in
ripened bananas. For example, this source stated that green bananas contained
a large amount of starch which meant it does not taste very sweet but instead
plain. Starch is converted to glucose during ripening as it makes the sugar
content of bananas increase and therefore more edible for consumption. This
source helps confirm the previous experiment's scientific knowledge as they are
both very similar and back up my hypothesis.
Initial method
Preparation of serial dilution
1) Using a stock solution of known glucose concentration, add 4ml of glucose to
a test tube, and use a pipette to accurately transfer glucose solution to a test
tube.
2) Using a pipette, transfer 2ml of glucose from the previous test tube into
another test tube and add 2ml of distilled water. Label test tube.
3) Repeat step 2 three times to complete the dilution series of glucose
Testing of serial dilution
1) Add 2-3 drops of quantitative Benedict’s solution to each test tube.
2) Place test tubes in a hot water bath of at least 40˚C for 5-10 minutes.
3) After 5-10 minutes, remove the test tubes from the water bath and wait for a
white precipitate to fully form
4) Fill cuvettes ¾ full with each solution from the test tubes
5) Calibrate a colorimeter using a cuvette of distilled water and set to the red
filter
6) Place each cuvette into the colorimeter and record the absorbance for each in
a suitable table
7) From the absorbances recorded, produce a calibration curve by plotting the
concentration of glucose against the absorbance of glucose
Preparation of samples
1) Firstly, to prepare samples, place one of the bananas you are using on a flat
surface and use a scalpel to cut the banana into approximately 5cm in length,
ensure each piece weighs 1g using a scale.
2) Place the cut portion of the banana into a mortar and add 20cm3 of 60˚C
water, then grind using a pestle for 5 minutes.
3) Filter the solution into a beaker using a sieve and filter paper to remove any
solid in the solution. Label the beaker with the sample used to avoid confusion
between samples.
4) Repeat steps 1-3 for the other bananas being used.
Benedict’s test
2
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 6: Investigative Project
1) Transfer 5cm3 of the sample in the beaker, using a pipette to a test tube and
add 1-2 drops of Benedict’s solution to the test tube.
2) Place the test tube into a water bath set to 45˚C for 10 minutes and allow the
test tube to reach a temperature of 45˚C.
3) Remove the test tube after 10 minutes and record any observations in a
suitable table.
4) Calibrate a colorimeter to 680nm using a blank cuvette to measure the
absorbance of your solution.
5) Fill a cuvette ¾ full of the solution and place it in a colorimeter.
6) Record 3 absorbances for each solution and repeat steps 1-6 for the other
solutions being used.
Iodine test
1) Using a scalpel, cut a thin slice of the bananas you are using and transfer it to
a microscopic slide.
2) Add 1-2 drops of iodine solution to the slide and cover it with a coverslip.
3) Clip the slide onto the stage of an optical microscope and observe the slide
through the eyepiece, adjusting the focus with the fine adjustment knob.
4) Record observations of the colour on the slide in a suitable table.
5) Repeat steps 1-4 for the other bananas being used.
Preliminary results table
Glucose serial dilution results
The results shown below have been recorded to 4 significant figures to ensure
data recorded has a high degree of precision and is appropriate.
Test tube Absorbance at 680nm (Au) Average absorbance
(Au)
Readin Readin Readin
g1 g2 g3
1 0.700 0.690 0.700 0.700
2 0.640 0.640 0.640 0.640
3 0.530 0.520 0.530 0.530
4 0.280 0.270 0.280 0.280
5 0.190 0.190 0.190 0.190
Banana sample result
Banana sample Absorbance at 680nm (Au) Average absorbance
3
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 6: Investigative Project
Assignment 6C + D: Undertake the project, collecting,
analysing, and presenting the results; review the
investigative project using correct scientific principles
Concentration of sugar in ripening bananas
Abstract
The overall aim of this practical investigation is to determine whether the
ripeness of bananas varies glucose content. The hypothesis for this investigation
is that as a banana’s ripeness increases, the sugar concentration will increase.
The results were produced by making a serial dilution of glucose and by
measuring the absorbance of banana samples using a colorimeter. The
absorbance readings of the banana samples were used with a calibration curve
of glucose to identify the glucose content of the banana samples. The overall
results showed that as the ripeness of the banana samples increased, so did the
content of glucose in the banana which was the hypothesis made prior to the
experiment. In terms of statistical significance, a statistical T-test was carried out
in addition to standard deviation which displayed that the results produced were
found to be statistically significant. This meant that the null hypothesis could be
rejected, and the alternative could be accepted- as a banana's ripeness
increases, the sugar concentration will increase. An overall conclusion was made
from the results along with the statistical tests performed- the ripeness of
bananas does vary glucose content as in bananas with a high degree of ripeness,
the glucose concentration is higher comparison to bananas with a lower degree
of ripeness.
Hypothesis
Hypothesis: As a banana's ripeness increases, the sugar concentration will
increase.
Null hypothesis: As a banana's ripeness increases, the sugar concentration will
stay the same.
Variables
Independent variable: Degree of ripeness based on colour and days of ripening
Dependent variable: Concentration of sugar in the bananas using colorimetry
and glucose calibration curve
Control variables: Type of banana (used bananas from same bunch), the mass of
the banana (measured using scale), the temperature
kept in (stored at room temperature)
Background
An experiment conducted by Al-bio (1) showed that the riper the banana, the
sweeter it is since a large proportion of starch is converted into sugars during the
ripening process. This increases the concentration of sugar in ripened bananas.
1
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 6: Investigative Project
Therefore, the higher the degree of ripeness of bananas, the greater the
concentration of sugar in bananas.
Another experiment was carried out on the sugar concentration in bananas and
this experiment included a hypothesis backed up by scientific knowledge (2).
This source explained how the content of sugars in bananas is highest for the
ripest bananas, e.g., yellow bananas, due to the lower content of starch in
ripened bananas. For example, this source stated that green bananas contained
a large amount of starch which meant it does not taste very sweet but instead
plain. Starch is converted to glucose during ripening as it makes the sugar
content of bananas increase and therefore more edible for consumption. This
source helps confirm the previous experiment's scientific knowledge as they are
both very similar and back up my hypothesis.
Initial method
Preparation of serial dilution
1) Using a stock solution of known glucose concentration, add 4ml of glucose to
a test tube, and use a pipette to accurately transfer glucose solution to a test
tube.
2) Using a pipette, transfer 2ml of glucose from the previous test tube into
another test tube and add 2ml of distilled water. Label test tube.
3) Repeat step 2 three times to complete the dilution series of glucose
Testing of serial dilution
1) Add 2-3 drops of quantitative Benedict’s solution to each test tube.
2) Place test tubes in a hot water bath of at least 40˚C for 5-10 minutes.
3) After 5-10 minutes, remove the test tubes from the water bath and wait for a
white precipitate to fully form
4) Fill cuvettes ¾ full with each solution from the test tubes
5) Calibrate a colorimeter using a cuvette of distilled water and set to the red
filter
6) Place each cuvette into the colorimeter and record the absorbance for each in
a suitable table
7) From the absorbances recorded, produce a calibration curve by plotting the
concentration of glucose against the absorbance of glucose
Preparation of samples
1) Firstly, to prepare samples, place one of the bananas you are using on a flat
surface and use a scalpel to cut the banana into approximately 5cm in length,
ensure each piece weighs 1g using a scale.
2) Place the cut portion of the banana into a mortar and add 20cm3 of 60˚C
water, then grind using a pestle for 5 minutes.
3) Filter the solution into a beaker using a sieve and filter paper to remove any
solid in the solution. Label the beaker with the sample used to avoid confusion
between samples.
4) Repeat steps 1-3 for the other bananas being used.
Benedict’s test
2
, H.
BTEC L3 EXTENDED DIPLOMA IN APPLIED SCIENCE
Unit 6: Investigative Project
1) Transfer 5cm3 of the sample in the beaker, using a pipette to a test tube and
add 1-2 drops of Benedict’s solution to the test tube.
2) Place the test tube into a water bath set to 45˚C for 10 minutes and allow the
test tube to reach a temperature of 45˚C.
3) Remove the test tube after 10 minutes and record any observations in a
suitable table.
4) Calibrate a colorimeter to 680nm using a blank cuvette to measure the
absorbance of your solution.
5) Fill a cuvette ¾ full of the solution and place it in a colorimeter.
6) Record 3 absorbances for each solution and repeat steps 1-6 for the other
solutions being used.
Iodine test
1) Using a scalpel, cut a thin slice of the bananas you are using and transfer it to
a microscopic slide.
2) Add 1-2 drops of iodine solution to the slide and cover it with a coverslip.
3) Clip the slide onto the stage of an optical microscope and observe the slide
through the eyepiece, adjusting the focus with the fine adjustment knob.
4) Record observations of the colour on the slide in a suitable table.
5) Repeat steps 1-4 for the other bananas being used.
Preliminary results table
Glucose serial dilution results
The results shown below have been recorded to 4 significant figures to ensure
data recorded has a high degree of precision and is appropriate.
Test tube Absorbance at 680nm (Au) Average absorbance
(Au)
Readin Readin Readin
g1 g2 g3
1 0.700 0.690 0.700 0.700
2 0.640 0.640 0.640 0.640
3 0.530 0.520 0.530 0.530
4 0.280 0.270 0.280 0.280
5 0.190 0.190 0.190 0.190
Banana sample result
Banana sample Absorbance at 680nm (Au) Average absorbance
3
