Biology 110 Lab practical 2

Spinning magnet created a vortex that drew oxygen into the water

30 mins → oxygen saturated water

Blue in nm

400

green in nm

550 middle isnt absorbed very well so it is reflected

red in nm

700

Chlorophyll a & Chlorophyll b

Absorb strongly in the blue region

DPIP die

Blue when oxidized

Energy equation

E= 2*10^(-16)/wavelength plug in wavelength to get E then take the amount of energy it was increased by and put that over the calculated E and you get a %

Change in absorbance over time You measured the loss of blue color (i.e., the reduction of DPIP) by noting the change in absorbance over time.

In the oxidation of water lab that utilized the blue dye DPIP, which of the following represents a measured (dependent) variable

The PFR was varied by adjusting the distance between the light source and the tube containing Chlorella

In the oxygen production lab, how was PFR varied?

A tank of water was placed in the light path to absorb heat.

In the oxygen production lab, what compensation was made for the heat generated by the lamps?

variables in photo system 1

Independent variable: x axis: Wavelength of light (nanometers) Dependent variable: y axis: Absorbance

Presence of heat & light → lot of change in DPIP

Summary: how fast is oxygen being made

The carotenes extracted in our lab were contaminated with chlorophyll; the carotenes used in the textbook were not contaminated with chlorophyll.

The absorption spectrum of carotenes as determined in lab sometimes showed an absorption peak in the red region of the spectrum. However, the absorption spectrum of carotenes shown in the textbook did not show such a peak. What caused this difference?

The oxidation of water. When water is oxidized in photosynthesis it looses electrons. Those electrons are available to reduce DPIP.

The reduction of DPIP by chloroplasts was coupled to which reaction below?

To eliminate pH as a variable in the experiment. The buffer maintained constant pH.

What was the purpose of using a buffer for the isolation and function assessment of chloroplasts?

Sodium bisulfite. and Illuminated chloroplasts.

Which of the following are capable of reducing DPIPox

Sodium bisulfite and chloroplasts may cause DPIP that is initially blue in solution to become colorless. Both sodium bisulfite and chloroplasts may reduce DPIP. DPIP looses its color when it becomes reduced.

Which of the following do chloroplasts and sodium bisulfite hold in common?

Comparing the absorbance changes in separate tubes in which increasing amounts of chloroplasts were added Showing that increasing amounts of chloroplasts increase the rate of DPIP reduction provides evidence that chloroplasts are the active ingredient in this experiment.

Which of the following exercises that you performed in lab best shows that chloroplasts play a crucial role in the color change of DPIP?

Measure its absorbance over a range of different wavelengths of light.

Which of the following is done to determine the absorption spectrum of a substance?

Chlorophyll b had an absorption peak the red region of the visible spectrum. Chlorophyll b had an absorption peak the blue region of the visible spectrum.

Which of the following is/are true of the absorption spectrum of chlorophyll b as studied in lab?

Carotene is more soluble in ethanol than in petroleum ether.

Which of the following is/are true of the solubilities of the pigments studied in lab?

600 Blue solutions strongly absorb light in the red region (~600nm) of the visible spectrum

Which of the following wavelength settings is best for having a Spec 20 detect the absorbance of light by a substance that is blue in solution?

Chlorophyll and Carotene

absorbing blue photons the best/most (shorter wavelength =higher energy)

removed oxygen

by reaction water with sodium sulphide

Photosystems

capture light energy and supply that energy to the electrons → electrons are energized twice by light in the photosystems

DPIP

captures the electrons after photosystem II: intercepts

photosynthesis 1

excite electrons to produce ATP and reduce NADP ox

high energy electrons

given to/deposited to an electron carrier called NADP

light alone in the oxidation of water (2)

greatest loss of blue color

Water (losing e-, oxidized) and DPIP (reduced)

happens at same rate so the line is positive increase

relationship between wavelength and photon

inversely proportional... longer the wavelength the lower the energy of the photon

PFR vs. rate of 02

line goes up and is positive

Device used measured the oxygen concentration and converted it into an electrical signal

make a conversion factor to convert milli voltage into oxygen concentration (8.3x=computer read out mV) so x= 1mV or mg/L of dissolved oxygen

NADP

oxidized and turned into a high energy electron carrier NADPH

water

provides the electrons that reduce the DPIP... electrons are given to the CO2 reduced -> sugar

Dependent variable in DPIP lab (2)

rate of water oxidation

Bisulfate added to the blank

reduced the DPIP so the blank had everything that the experimental tube had minus the blue color

ATP

reduces NADP and CO2 and other compounds

Ethanol

specifically was able to draw the carotene pigment

Methanol

specifically was able to draw the chlorophyll b

Petroleum ether

specifically was able to draw/extract the chlorophyll a

Water

supplies low energy electrons

mL chloroplasts

x axis : Independent variable

photosynthesis 3 Independent variable

x-axis: quantity of light shining on photosystems

rate of Reaction:

y axis : Dependent variable

photosynthesis 3 Dependent variable

y-axis: rate of O2 production