Bio Unit 3

The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?

• Green and yellow wavelengths inhibit the absorption of red and blue wavelengths.
• Oxygen given off during photosynthesis interferes with the absorption of light.
• Aerobic bacteria take up oxygen, which changes the measurement of the rate of photosynthesis.
• Other pigments absorb light in addition to chlorophyll a. 

On Sept. 15, 1883, The University of Texas at Austin opened with one building, eight professors, one proctor, and 221 students. That same year, Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light. Which of the following statements describe a relationship that Engelmann's experiment helped to determine?

• the relationship between wavelength of light and the rate of photosynthesis
• the relationship between wavelength of light and the rate of aerobic respiration
• the relationship between wavelength of light and the amount of heat released
• the relationship between carbon dioxide concentration and the rate of photosynthesis

The mechanism of photophosphorylation is most similar to which of the following processes?

• substrate-level phosphorylation in glycolysis
• oxidative phosophorylation in cellular respiration
• the Calvin cycle
• reduction of NADP+

What wavelength of light in the figure is most effective in driving photosynthesis?

• 420 nm
• 575 nm
• 625 nm
• 730 nm

Which of the following processes would be most directly affected if a thylakoid membrane is punctured so that the interior of the thylakoid is no longer separated from the stroma?

• synthesis of ATP
• flow of electrons from photosystem II to photosystem I
• splitting of water
• reduction of NADP+

In photosystem II, P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?

• It is the receptor for the most excited electron in either photosystem of photosynthesis.
• It is the molecule that acquires electrons from the electron transfer system (aka ETC).
• It transfers to reduce NADP+ to NADPH.
• It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has. 

To identify the molecule that accepts CO_2, Calvin and Bensons manipulated the carbon-fixation cycle by either cutting of CO₂ or cutting off light from cultures of photosynthetic algae. They then measured the concentrations of various metabolites immediately following the manipulation. How would these experiments help identify the CO₂ acceptor?

• CO₂ acceptor concentration would decrease when either the CO₂ or light are cut off. 
• CO₂ acceptor concentration would increase when either the CO₂ or light are cut off. 
• CO₂ acceptor concentration would decrease when the CO₂ is cut off, but increase when the light is cut off. 
• CO₂ acceptor concentration would increase when the CO₂ is cut off, but decrease when the light is cut off. 

In the process of carbon fixation, rubisco attaches a CO₂ to produce a 6 carbon molecule, which then splits into two intermediate organic molecules. To complete the cycle, what else must occur?
I. addition of a apart fo electrons from NADPH
II. inactivation of RuBP carboxylase enzyme
III. regeneration of rubisco
IV. regeneration of RuBP
V. oxidation of G3P by NADPH

• V.
• I. and II.
• III. and IV. 
• I. and IV.

A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights that is set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask. The dissolved oxygen in the flask with algae will ________.

• always be higher
• always be lower
• be the same as the control in the light or dark
• be higher in the light, but lower in the dark 

How is photosynthesis similar in C₄ plants and CAM plants?

• In both cases, only photosystem I is used. 
• Both types of plants make sugar without the Calvin cycle.
• In both cases, rubisco is not used to "fix" carbon initially. 
• Both types of plants make most of their sugar in the dark.