Photosynthesis Processes and Molecules

The light reactions produce ________, which are used in the Calvin cycle. The Calvin cycle releases ________, which return to the light reactions.

• ATP and CO₂; glucose and O₂

• ATP and NADPH; ADP and NADP  

• ADP and NADH; ATP and NADPH

• CO₂ and H₂O; glucose and O

• glucose and O₂; CO₂ and H₂O

Sucrose, cellulose, amino acids, and starch are all made from what starter molecule in plants?

• glucose

• ATP

• fructose

• RuBP carboxylase

• glyceraldehyde 3-phosphate (G3P)

ATP and NADPH are both used during the Calvin cycle. What is the function of each?

• ATP and NADPH are joined into the starter molecule, RuBP, to form glucose.

• ATP supplies energy and NADPH supplies electrons for reducing power.

• Both ATP and NADPH supply energy to the Calvin cycle.

• ATP supplies energy and NADPH fixes CO₂ so it can enter the cycle.

• NADPH supplies energy and ATP supplies electrons for reducing power.         

In photosynthesis, the light reactions ________ while the Calvin cycle ________.

• can only function if the stomata are open; can only occur if the stomata are closed

• can occur only in the light; can occur only in the dark

• use products manufactured in the dark reactions; creates products used in the dark reactions

• capture solar energy; converts the captured energy to chemical potential energy

• require the presence of ATP; makes ATP

Which steps of photosynthesis does C₄ photosynthesis partition in space?

• carbon fixation and light reactions

• 1,3 bisphosphoglycerate (BPG) formation and glucose phosphate formation

• glyceraldehyde 3-phosphate (G3P) formation and glucose phosphate formation

• carbon fixation and Calvin cycle reactions

• light reactions and Calvin cycle reactions

CAM photosynthesis limits CO₂ fixation to nighttime hours in order to

• limit the Calvin cycle reactions to nighttime only.

• open stomata only at night, limiting water loss because of heat and low humidity.

• limit water uptake from the soil during daytime hours.

• allow water to enter leaf spaces during the daylight hours.

• allow NADPH and ATP to enter leaf spaces.

The _______ from the light reactions is used to reduce CO₂ to a carbohydrate using energy derived from ______.

• NADPH; ATP

• NADPH; RuBP

• rubisco; RuBP

• NADP⁺; ATP

• RuBP; ATP

The light reactions of photosynthesis are said to be similar to a battery because they form a current. In which direction do the electrons of this circuit flow?

• H₂O → PSII → electron transport chain → PSI → electron transport chain → NADPH

• NADPH → PSII → electron transport chain → PSI → electron transport chain → NADP⁺

• PSI → electron transport chain → PSII → electron transport chain → NADPH

• NADP⁺ → PSII → electron transport chain → PSI → electron transport chain → NADPH

• H₂O → PSII → chlorophyll b → PSI → chlorophyll a → NADPH

Why do plants contain other pigments besides chlorophyll?

• When the additional pigments break down, the chlorophyll can absorb other wavelengths of light.

• The additional pigments are able to absorb other light wavelengths that chlorophyll cannot.

• Chlorophyll is unable to absorb visible light.

• The additional pigments can only absorb violet or ultraviolet light.

• When chlorophyll breaks down, the additional pigments can absorb the same wavelengths of light.

Which compounds link the light reactions with the Calvin cycle reactions?

• ATP and NADPH

• G3P and ATP

• G3P and NADPH

• H⁺ and G3P

• H⁺ and ATP