Photosynthesis

Part A

Which process produces oxygen?

	Photosynthesis
	Cellular respiration

Correct

Oxygen is a by-product of the photosynthetic process.

Part B

Which set of reactions uses H2O and produces O2?

	The light-independent reactions
	The light-dependent reactions

Correct

The light-dependent reactions use H2O and produce O2.

Part C

What is the importance of the light-independent reactions in terms of carbon flow in the biosphere?

	The light-independent reactions turn CO2, a gas, into usable carbon in the form of sugars.
	The light-independent reactions turn glucose, a sugar, into CO2 gas.
	The light-independent reactions use CO2 to make ATP.
	The light-independent reactions turn sugar into ATP for energy.

Correct

CO2 is unusable until plants have "fixed" this carbon into sugar.

Part D

True or false? The light-dependent reactions of photosynthesis use water and produce oxygen.

	True
	False

Correct

The water molecules are split to replenish electrons in photosystem II, leaving behind protons, which are used to generate a proton gradient for the formation of ATP, and oxygen, which is released as a by-product.

Part E

Which of the following molecules is the primary product of photosystem I?

	Carbon dioxide
	NADPH
	ATP
	Oxygen

Correct

The NADPH produced by photosystem I is used to supply energy for the production of sugars during photosynthesis.

Part F

What is the biological significance of the light-independent reactions of photosynthesis?

	They convert carbon dioxide to sugar.
	They convert ATP to sugar.
	They make oxygen.
	They generate ATP and NADPH.

Correct

All organisms use the sugars produced by photosynthesis to generate energy.

Part G

Which of the following statements best describes the relationship between the light-dependent and light-independent reactions of photosynthesis?

	The light-independent reactions release energy, and the light-dependent reactions require energy.
	The light-dependent reactions produce carbon dioxide, which is then used by the light-independent reactions.
	The light-dependent reactions produce ATP and NADPH, which are then used by the light-independent reactions.
	The light-dependent reactions pass electrons through an electron transport chain to the light-independent reactions.

Correct

Light energy drives the formation of ATP and NADPH during the light-dependent reactions; these energy molecules are then used during the light-independent reactions to form sugars.

Part H

Which of the following reactions ensures that the Calvin cycle can make a continuous supply of glucose?

	Regneration of RuBP
	Production of G3P
	Production of 3-phosphoglycerate
	Carbon fixation

Correct

The regeneration of RuBP ensures that the Calvin cycle can proceed indefinitely, since RuBP fixes carbon dioxide into an organic molecule that is used to produce sugar.