lab report cromatoghraphy (autosaved).docx

7/24/2019 LAB REPORT cromatoghraphy (Autosaved).docx

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LAB REPORT BIOLOGY

PLANT PIGMENT

CROMATOGRAPHY

SYED SHAFIQ BIN SYED ZAINI

970407147109

TEACHERS NAME: MS. SAW BIN


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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.


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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.


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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.


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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.


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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.


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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

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