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The appearance of _____ on Earth due to the action of photosynthetic bacteria occurred about 2.7...

Question:

The appearance of _____ on Earth due to the action of photosynthetic bacteria occurred about {eq}2.7 {/eq} billion years ago.

(a) water

(b) oxygen

(c) carbon dioxide

(d) iron

(e) ATP.

Early Photosynthesis on Earth:

Photosynthesis is the process of harvesting light energy to make chemical energy. During the light-dependent reactions, electrons in photosynthetic pigment molecules are excited by light. This energy is transferred between pigment molecules until one loses an excited electron to an electron transport chain (ETC) embedded in a photosynthetic membrane. The resulting generation of a proton gradient is used to make ATP, and the electron at the end of the ETC is used to reduce NAD(P){eq}^+ {/eq} to make NADH or NADPH. A reduced molecule also donates an electron to the pigment molecule that lost its electron to the ETC. The ATP and NADH/NADPH generated during the light-dependent reactions is then used during the light-independent reactions to drive the fixation of CO{eq}_2 {/eq} to make organic molecules.

While today, we commonly consider photosynthesis to be oxygenic, forming O{eq}_2 {/eq}, many photosynthetic bacteria, including the green and purple photosynthetic bacteria, are anoxygenic, meaning that their photosynthetic processes do not generate O{eq}_2 {/eq}. Like today's anoxygenic photosynthesizers (purple and green bacteria), instead of using H{eq}_2 {/eq}O as the electron donor, anoxygenic photosynthesizers use other reduced molecules like H{eq}_2 {/eq}S, H{eq}_2 {/eq}, or reduced organic molecules.

The summary equation for photosynthesis is shown here.

Answer and Explanation: 1

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The appearance of _____ on Earth due to the action of photosynthetic bacteria occurred about {eq}2.7 {/eq} billion years ago.

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Photosynthesis Equation Lesson for Kids

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Chapter 5 / Lesson 4
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Photosynthesis, the process plants use to make food, can be calculated through the photosynthesis equation. Discover how plants combine water, carbon dioxide, and sunlight to make oxygen and glucose. Also, learn how plants store excess glucose.


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