EXERCISE NO. 3 Flashcards
Title
Photosynthesis
the main function of leaves
photosynthesis
the manufacture of sugar through participation of carbon dioxide and water in the chloroplast with the use of light energy and the release of oxygen
photosynthesis
formula
carbon dioxide + water — ( light, chlorophyll) –> glucose + oxygen
both ____ and _____ features of the leaf enable photosynthesis to proceed
external and internal
through photosynthesis the green plants: construct _______ from water, mineral, and gases ; captures the energy of the sun’s light waves and converts it into a biologically usable form of ___________ energy; and replenishes the atmosphere of the earth with _______.
organic compound
chemical energy
oxygen
for photosynthesis to transform light energy from the sun into chemical energy (______ energy) in plants, ___________ absorb light to power the chemical reactions.
bond energy
pigment molecules
are macromolecules produced by the plant and these pigments absorb specified wavelengths of visible light to provide the energy required for photosynthesis
plant pigments
________ is necessary for photosynthesis, but ________ collect and transfer energy to chlorophyll.
chlorophyll
accessory pigments
Although pigments absorb light, the wavelengths of light that are not absorbed by the plant pigments are
reflected back to the eye
are the colors we see in observing the plant
reflected wavelengths
four pigments that may separate out into their respective colors are
chlorophyll a - blue green color
chlorophyll b - pale green color
xanthophylls - pale yellow color
carotene - orange yellow color
least soluble pigment
chlorophyll b
most soluble pigment
carotene
the easiest way to analyze th pigments is to separate them using ________
paper chromatography
works on the principle that different pigments, when dissolved in a solvent will move through a piece of paper at different rates
paper chromatography
examples of solvent used in paper chromatography
petroleum ether and acetone
is determined by how soluble the pigment is in the solvent and the degree of adhesion of the pigment to the surface of paper
rate
the pigments are carried at different rates because they are ____
not equally soluble
a pigment that is ______ soluble will travel the greatest distance and a pigment that is _____ soluble will move shorter distance
most soluble = greater distance
less = shorter distance
is unique for that pigment in set conditions and is used to identify the pigment
the distance the pigment travels
the ratio or retention factor
Rf = distance traveled by the pigment/ distance traveled by the solvent 😡
objectives
- demonstrate the role of pigments in photosynthesis
- isolate and identify photosynthetic pigments in Mayana, San Francisco, or star apple leaves
- calculate Rf values of photosynthetic pigments
star apple
CHRYSOPHYLLUM CAINITO
mayana
COLEUS BLUEMEI
San Francisco
CODIAEUM VARIEGATUM
What do you call the solvent used for paper chromatography?
Chromatogram Solvent
Chromatogram solvent is made up of?
95% petroleum ether and 5% percent acetone
the set-up should be observed for ___ minutes
15
is a point where the mobile phase travelled before the stationary phase was removed
Solvent front
mobile phase
the solvent
stationary phase
paper
The differential adsorption to the paper and the differential solubility of these pigments in the solvent has effectively done what to the pigments in the plant leaves
separate
Chromatogram solvent is composed of two solvents, petroleum ether and acetone. Why are two solvents used in the process?
Petroleum ether is a nonpolar solvent that helps dissolve nonpolar pigments like carotenoids found in lichens, while acetone is a polar solvent that dissolves more polar pigments like chlorophylls. By using a combination of these solvents, a broader range of pigments can be extracted and separated, allowing for a more comprehensive analysis of the lichen’s pigment composition. The two solvents complement each other in their ability to dissolve different types of pigments, facilitating a more complete pigment separation.
what if the significance of the Rf values?
The Rf (Retention Factor) values in chromatography are significant because they provide quantitative information about the separation of compounds in a mixture. A higher Rf value indicates that a compound has moved a greater distance relative to the solvent front, suggesting it’s more soluble in the mobile phase and less attracted to the stationary phase. This information helps in identifying and characterizing the components of a mixture, making Rf values a valuable tool in analytical chemistry.
why are plants generally green
Plants are generally green because of the presence of a pigment called chlorophyll. Chlorophyll molecules absorb light most efficiently in the blue and red parts of the electromagnetic spectrum but reflect green light, giving plants their characteristic green color. This reflects the fact that green light is less absorbed by chlorophyll and is instead transmitted or reflected, making it the predominant color that we perceive in plants.
