8.1 Energy and Life

ATP can easily release and store energy by breaking and re-forming the bonds between its phosphate groups. This characteristic of ATP makes it exceptionally useful as a basic energy source for all cells.

In the process of photosynthesis, plants convert the energy of sunlight into chemical energy stored in the bonds of carbohydrates.

• adenosine triphosphate (ATP) (226)

• autotroph (228)

• photosynthesis (228)

• heterotroph (228)

8.2 Photosynthesis: An Overview

Photosynthetic organisms capture energy from sunlight with pigments.

An electron carrier is a compound that can accept a pair of high-energy electrons and transfer them, along with most of their energy, to another molecule.

Photosynthesis uses the energy of sunlight to convert water and carbon dioxide (reactants) into high-energy sugars and oxygen (products).

• pigment (230)

• chlorophyll (230)

• thylakoid (231)

• stroma (231)

• NADP⁺ (232)

• light-dependent reactions (233)

• light-independent reactions (233)

8.3 The Process of Photosynthesis

The light-dependent reactions use energy from sunlight to produce oxygen and convert ADP and NADP⁺ into the energy carriers ATP and NADPH.

During the light-independent reactions, ATP and NADPH from the light-dependent reactions are used to produce high-energy sugars.

Among the most important factors that affect photosynthesis are temperature, light intensity, and the availability of water.

• photosystem (235)

• ATP synthase (237)

• electron transport chain (236)

• Calvin cycle (238)

Think Visually Using the information in this chapter, complete the following flowchart about photosynthesis.

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