PURDUE BIOL 110 Lab Practical #2

Ethanol

Corresponds to carotene

Ether

Corresponds to chlorophyll A

Methanol

Corresponds to chlorophyll B

Linear (As PFR increase, oxygen production rate also increases)

Graphically, what is the relationship between oxygen production rate and PFR?

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?

High energy levels

More light -> excited electrons -> __________

The poison blocks the oxidation of water, the poison blocks the transfer of electrons from #1 to #2, and the poison blocks the transfer of electrons from #2 to #3

Note the electron carriers in the thylakoid membrane above. When chloroplasts are exposed to light, an electron acceptor, DPIP, is reduced by electrons from carrier #3. When a particular plant poison is added to illuminated chloroplasts, DPIP is not reduced. Which of the following explains that observation?

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?

oxidation of water

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

False (They are INVERSELY related. i.e. 450nm wavelength will have HIGHER ENERGY than a photon with a 650nm wavelength)

True or False: The energy associated w/ a photo is CONVERSELY related (ex. a photon w/ a 450nm wavelength has LOWER energy)?

Light source, monochromator, test tube, light detector, amplifier, and readout.

What are the 6 main parts of the Spec 20?

It is being reduced (gaining electrons)

What is happening to DPIP when it loses its blue color?

Rate of water oxidation

What is the DEPENDENT variable in the Oxidation of Water lab?

The rate at which Chlorella produces oxygen

What is the DEPENDENT variable in the production of oxygen lab?

Light quantity (PFR)

What is the INDEPENDENT variable in the production of oxygen lab?

The amount of chloroplasts added to the reaction mixture

What is/are the INDEPENDENT variable(s) of the Oxidation of Water Lab?

To eliminate pH as a variable in the experiment

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

Petroleum Ether

What was the top layer in both separations?

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

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

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 AND 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

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?