Upload
syed-shafiq-syed-zaini
View
218
Download
0
Embed Size (px)
Citation preview
7/24/2019 LAB REPORT cromatoghraphy (Autosaved).docx
1/7
LAB REPORT BIOLOGY
PLANT PIGMENT
CROMATOGRAPHY
SYED SHAFIQ BIN SYED ZAINI
970407147109
TEACHERS NAME: MS. SAW BIN
7/24/2019 LAB REPORT cromatoghraphy (Autosaved).docx
2/7
Pl!" P#$%&!" C'()%")$(*'+
Introduction:
Chlorophylls are greenish pigments that have a special structure to provide
energized electrons to other molecules. There are several types of chlorophyll but
the most important one is chlorophyll a. Chlorophyll a passes its energized electrons
on to molecules that will manufacture sugars and other carbohydrates. All plants that
photosynthesize contains chlorophyll a and only some does not has chlorophyll b.
Accessory pigments absorb light energy and transfers energy to chlorophyll a during
photosynthesis. Two accessory pigments are carotenes and xanthophyll. Pigmentscapture the light energy needed for photosynthesis.
Photosynthesis is a naturally occurring process that takes place in plants algae and
even some forms of bacteria. They utilize the sunlight energy to convert C!"into
carbohydrates. Photosynthesis is an essential part of life on #arth. $uring
photosynthesis C!"expelled by animals and humans is absorbed and oxygen is
created. There are some forms of bacteria that perform an oxygenic photosynthesis
and no oxygen is released. This makes photosynthesis the counterpart of cellular
respiration.
Carotene is the most soluble pigment because it makes no hydrogen bonds with
cellulose a ma%or component of cell walls so this pigment will move furthest along
with the solvent during the chromatography. &anthophyll is not carried as far as
carotene because it is less soluble in solvent and is slowed down by the hydrogen
bond to cellulose of the cell wall. 'n plant chromatography solvents move up paper it
separates the pigments into its components. The colours that are seen on the paper
are plant pigment. (sing the formula )f* distance pigment migrate +mm, - distance
solvent front migrated +mm, one can determine the distance moved by the pigment
to the distance moved by the solvent.
Researchquestion: hat is the leaf pigment present in leaves/
Hypothesis: ' predict that the yellow0greenish colour pigment +chlorophyll b, and
dark green pigment +chlorophyll a, can be found in the leave pigment because plant
needed chloroplast which contained chlorophyll to carry out photosynthesis.
7/24/2019 LAB REPORT cromatoghraphy (Autosaved).docx
3/7
Variables:
a, 'ndependent: 1tarting line
b, $ependent: )atio travelled +)f,c, Controlled: Propanone ethanol grass leave
Materials:
02eave samples 0344cm5beaker
01cissors 0Pencil
0Pestle and mortar 0Threads
0Propanone
0#thanol
06ilter paper
Procedure:
3. Cut and measured a length of filter paper that is about 3cm longer the beaker.
". Cut a point at the end of the paper to a sharped end.5. A horizontal line is drawn %ust under the spot to form the starting point for the
chromatography.7. Cut a handful of leaves into small pieces and placed them in the pestle.8. The leaves are grinded with ethanol.9. The concentrated extract of the leave %uice is collected by using dropper.. The leave extract is placed onto the filter paper about " cm from the sharped
end.;. The pigment spot is allowed to dry to prevent it from spreading.
7/24/2019 LAB REPORT cromatoghraphy (Autosaved).docx
4/7
3". After 54 minutes the paper is removed from the beaker and ' marked the
position of the solvent front instantly by using a pencil.35.The distance travelled by the solvent the distances travelled by each pigment
and the colours of each pigment that can be seen is marked measured and
recorded.
37.The distances from the starting point to the solvent front and from the startingpoint to each colour centre spot and the )fvalues are calculated.
$ata collection:
=umber of
chromatograp
hy paper
$istance
solvent
migrated+mm,-a
Colour of
pigment
$istance
pigment
migrated+mm,-b
)f*
b
a
3 " dark green 4 4.
7/24/2019 LAB REPORT cromatoghraphy (Autosaved).docx
5/7
1 , - 40./
0.
0.9
0.9,
0.94
0.9/
0.9
Graph of Rf against colour of pigment
D( $(&&!
Y&ll) $(&&!
$iscussion:
3. 'n this experiment only one type of leave was used the colour of pigment that
was identified are dark green and yellow green. ?oth of the dark green andyellow green pigment found are chlorophyll because green plant has chloroplast
which contained chlorophyll as the pigment. Chlorophyll is needed in the
photosynthesis because it will absorb the energy from the sunlight.
". There are more than one pigment in the leave because each of the pigment
have their own different role which is they are absorbing different wavelength of
light the two pigment identified are both chlorophyll +a and b, because they are
green in colour and they have different weight and polarity that is considered as
the factor that cause the different )fvalues of both pigments. They both play the
same role during the photosynthesis.
5. The )fvalue of chlorophyll b is lower than chlorophyll a because they have
different polarity. ?y using propanone as the solvent during the chromatography
the )fvalue for chlorophyll a in each leaves is 4.
7/24/2019 LAB REPORT cromatoghraphy (Autosaved).docx
6/7
up the plate than others.The higher level of the pigment on the chromatogram
indicates that the chlorophyll a which is at the higher level than chlorophyll b has
higher solubility. The molecular size of the chlorophyll a itself is smaller.
8. Temperature maybe a key variable that must considered because the solvent
that used is volatile which is meant that is it easy to vaporize. hen the
temperature of the surrounding is higher the propanone will be easier to
vaporize. 1o that it will affect the laboratory result so when comparing it with
the published data it will not approximately accurate.
9. 1ome factors that affect paper chromatography are :
a, 1olvent: A certain solvent will only attract certain pigments up the
paper. This means that only certain pigment wilt travel with movement of the
solvent. The grass leave contained green pigments that were identified by
me. These are reBuired by the plant to undergo photosynthesis.b, 1ize of the particle: The smaller the size of the particles the smaller the )f
value. The level of chlorophyll a is higher than chlorophyll b this indicates
that chlorophyll b has bigger molecular size than chlorophyll a. hen then
the size is bigger its polarity is higher too. This affects the )fvalue and its
efficiency to absorb energy from sunlight.c, 1olubility: !nly certain pigments of plant can be soluble in the solvent so '
should use more than one solvent. 'n this experiment chlorophyll a and b
were identified this indicates that chlorophyll is soluble in propanone.
. hen using different solvent the )fwill be different. 't is because when differentsolvent is used the )fwill be different. 6or example chlorophyll b is only soluble
in fat solution.;. 'n the reaction centre chlorophyll that presents is chlorophyll a. 't is used during
the photosynthesis to absorb energy from sunlight chlorophyll will absorb ray of
blue colour and red colour. The other pigments which are accessory pigment will
absorb other light ray of different colour.
7/24/2019 LAB REPORT cromatoghraphy (Autosaved).docx
7/7
Conclusion:
The hypothesis was correct ' able to identify the colour of pigment that were
predicted which were yellow0greenish colour pigment +chlorophyll b, and dark green
pigment +chlorophyll a,. The colours separations are because of the differences in
their molecular structure specifically their solubility in solvent+propanone, and their
rate of absorption by the paper. et the ) f values were not the same as the published
one because of some errors which are time and the measurement.
)eferences:
http:--www.ukessays.com-essays-biology-lab0report0on0plant0pigments0and0
photosynthesis0biology0essay.phpDixzz5y