Photosynthesis Chromatography Lab: LabBench

In paper chromatography the pigments are dissolved in a solvent that carries them up the paper. To separate the pigments of the chloroplasts, you must use an organic solvent.

http://www.phschool.com/science/biology_place/labbench/lab4/design1.html

The next screen shows you the separation of plant pigments.

In order to get a thin line like the one above, you can roll  coin on a leaf over the chromatography paper.

The colors that appear on the chromatography paper show the possible pigments the material is made of, in this case it is made out of chloroplasts.

 

 The migration of pigment relative to migration of solvent is expressed as a constant, R_f (Reference front). It can be calculated by using the formula:

 

 

Lab Quiz from Lab bench


1. Look again at the chromatogram you completed in the previous exercise. Which of the following is true for your chromatogram?

	a.	The Rf for carotene can be determined by dividing the distance the yellow-orange pigment (carotene) migrated by the distance the solvent front migrated.
	b.	The Rf value of chlorophyll b will be higher than the Rf value for chlorophyll a.
	c.	The molecules of xanthophyll are not easily dissolved in this solvent, and thus are probably larger in mass than the chlorophyll b molecules.
	d.	If this same chromatogram were set up and run for twice as long, the Rf values would be twice as great for each pigment.

Correct! R_f values are relative, and depend not on the total distance migrated, but on the relative distance migrated.
2. If a different solvent were used for the chlorophyll chromatography described earlier, what results would you expect?

	a.	The distances travelled by each pigment will be different, but the Rf values will stay the same.
	b.	The relative position of the bands will be different.
	c.	The results will be the same if the time is held constant.
	d.	The Rf values of some pigments might exceed 1.0.

Correct! Each pigment has different solubility in different solvents. You could expect a different sequence of pigment bands.
3. What is the R_f value for carotene calculated from the chromatogram below?

	a.	1.09
	b.	0.17
	c.	0.96
	d.	0.33
	e.	0.50

Correct! R_f = distance pigment migrates/ distance solvent front migrates, = 11.5/12, = 0.96.

Computer Transpiration Lab

Data Table

1.      Transpiration is like sweating for plants. Leaf and stem surfaces are dotted with stomata (small openings like pores) that are more numerous on the underside of the leaf. The function of transpiration is to cool the plant and allow the flow of minerals and nutrients from the root to shoot.

2.      A few controls are the heat, wind, and light tools, like the fan, heater, and the lamp. Another control is the time the plant is exposed to heating or cooling (1 hour).

3.      The change in environmental temperature by the heater or introducing wind with the fan or adding additional light with the lamp will increase the rate of transpiration. We found that for most plants had the highest rate of transpiration when we used the fan. All the plants rates of transpiration increased but not with the same proportion.

4.      The wind introduced by the fan increased the rate of transpiration for the most of the plants because the wind blows away water vapor from the plant resulting in a higher rate for transpiration.

5.      The Coleus had the highest rate of transpiration because it has a lot of large leaves which enable it to transpire more.  The rate of transpiration depends on the structure of the plant, like how large its leaves are.

6.      The rate of transpiration would decrease if you coated a plant with petroleum jelly because that would block the stomata and prevent the plant from evaporating water. It will eventually kill the plant.

7.      Transpiration is important for plants because it cools the plants and allows the flow of minerals and nutrients from the root to the shoot.

Plant Hormones

Auxin is a plant growth hormone, its major function is to help the plant grow by changing the plant wall plasticity making it easier for the plant to grow upward. Auxin also helps the root formation. Auxin is also the hormone responsible for phototropism, the process by which auxin is degraded on the outside of the plant, allowing the plants to slope towards the light. Auxin is also credited for growing quickly the plants central shaft, which is also known as apical dominance.

http://preuniversity.grkraj.org/html/6_PLANT_GROWTH_AND_DEVELOPMENT.htm

 

 

 

Abscisic acid (ABA) is produced to counter stress of environmental conditions such as dehydration, cold temperatures, and shortening day lengths. ABA counters the effect of hormones like auxins and inhibits stem elongation and induces dormancy in lateral buds. Abscisic acid also allows the plants to adapt to the stress in the environment. ABA blocks germination in buds and promotes storage of proteins, it protects young plants from sprouting too early during warm weather in winter.

https://labs.mcdb.ucsb.edu/finkelstein/ruth/

 

 

Ethylene is associated with fruit ripening, flower wilting, and leaf fall. It is also a volatile gas (C₂H₄₎. It is a growth hormone that helps convert starch and acids to sugars. Ethylene also triggers leaf and fruit abscission.

http://isopaninsulation.com/technologies/fruit-ripening-plants

Flowers and Coevolution

Observations of Rose:

·         Petals are pink and soft

·         Stems have thorns

·         No smell

·         Yellow pollen

·         Flower was open widely, making the pollen easily reachable

·         No insects

·         Surrounded by wood chips

 

Observations of Purple Flower:

·         Yellow pollen was towards the bottom of the flower

·         Has a good smell

·         Small insects in the flower

·         Soft purple petals

·         Small flower

             

Observations of Pomegranate Tree Flower:

·         Yellow pollen towards the top of the flower

o   Pollen easily reachable

·         Hard orange red petals

·         No insects

·         No smell

·         Long leaves on tree

 

 

 

Coevolution:

      While observing the flowers above, I noticed that the pollen was located at different parts of the flower. Also, the flowers have different colors and smells. These characteristics are a product of coevolution, because different flowers attract different insects or birds who help it pollenate the flower pollenate and maintain its species. At the same time, these birds and insects who feed on these flowers coevolved also in a way to make it able to feed on these flowers so it can maintain its species as well.