Exam 3 Review

which of the following statements about the Calvin cycle is true?

-Calvin and Benson used 14C radioisotope to determine the sequence of reactions in CO2 fixation -the three processes of the calvin cycle are fixation, reduction, and regeneration -during the reduction proceses, 3PG is converted to G3P which is the product of the calvin cycle

which of the following is true

-G3P can enter glycolysis or gluconeogenesis -protons pumped from the stroma into the thylakoids increase the pH, which activates rubisco -electron transport from photosystem 1 reduces disulfide bonds in Calvin cycle enzymes and activates them -C3 plants are more ancient than C4 plants

For every 6 CO2 fixed, the calvin cycle uses _____ molecules of NADPH, and _____ molecules of ATP.

12.....18

the first stable product synthesized during CO2 fixation is the sugar phosphate called

3-phosphoglycerate (3PG)

which is false?

NADPH is synthesized in the thylakoid lumen

In C4 and CAM plants, the primary CO2 fixing enzyme is

PEP carboxylase

which is false

PEP carboxylase fixes CO2 only when levels of CO2 are very high

Identify the correct statement

a photosystem is composed of pigments arranged in light-harvesting complexes around a reaction center

in noncyclic electron transport, oxidized chlorophyll in photosystem I returns to its reduced state by

accepting electrons from photosystem II through the electron transport chain

Which of the following is false?

accessory pigments always reflect light and do not contribute to photosynthesis

During chemiosmotic photophosphorlation by ATP synthase in the chloroplast, protons are moving

across the thylakoid membrane from the thylakoid lumen to the stroma

What was the conclusion from the above experiment

all the oxygen gas produced during photosynthesis comes from water

In CAM plants such as cacti, CO2 is fixed ____ to form a four-carbon molecule called _____ which is converted to malatew and stored in the the vacuoles of mesophyll cells for use in the calvin cycle_____

at night;oxaloacetate;during the day

Plants look green because

chlorophyll absorbs red and blue light and reflects or transmits green light

the electron transport chain that chain that exists between photosystem II and photosystem I

generates ATP

Which of the following statments is FALSE about cyclic electron transport?

it uses P680 reaction center only

which sequence gives a correct order of steps taking place during the light reactions?

light energy->excited electron->electron transport->ATP synthesis

the calvin cycle occurs in the

stroma of the chloroplast

the precise moment when light energy is transformed into chemical energy is the point at which

the P680 chlorophylls are oxidized

if 2 plants have different have different-colored leaves

their action spectra may match, but their absorption spectra will differ