lab practical 2

Which of the following is true concerning the energy of photons?

A 400 nm photon has more energy than a 740 nm photon. Photon energy is inversely related to photon wavelength: short wavelength means more energy.

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

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

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

Carotene is more soluble in ethanol than in petroleum ether.

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

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.

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

Chlorophyll b had an absorption peak at about 640 nm Chlorophyll b had an absorption peak at about at about 460 nm.

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

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.

In which of the following types of population growth is the rate of growth independent of population size?

Linear A fixed number of organisms reproduce each generation without regard to the total population size.

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

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

Which of the following are capable of reducing DPIP_ox?

Sodium bisulfite and Illuminated chloroplasts.

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

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.

In the oxygen production lab, how was PFR varied?

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

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

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

Without regard to the mode of population growth, which of the following best characterizes the rate of population growth?

The slope of the population size versus time graph at any point in time.

Which of the following characterize(s) exponential growth?

The slope of the population size versus time graph is proportional to population size.

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

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