Chapter 7 - Photosynthesis

Overview

• review of the concepts that there is a one-way flow of energy in ecosystems and a cycling of nutrients

• photosynthesis occurs in autotrophs (producers)

• aerobic respiration occurs in heterotrophs (consumers and decomposers)

• photosynthesis and aerobic respiration are linked to each other

• carbon dioxide + water + light energy --------> glucose + oxygen

• nature of light and what light the plant uses

• in higher plants, photosynthesis occurs in the leaves in the mesophyll cells in the chloroplasts

Light reactions

• capture light energy and convert it to chemical energy (ATP and NADPH)
• require chlorophyll
• take place in the thylakoid membrane of the chloroplast
• oxygen is released (as waste) when water is split

• the electron released from chlorophyll is given to an electron transport chain

• as the electron is passed along, it is used to do work (pumping H⁺)

• another chlorophyll catches the electron at the end of the chain

• the second electron needed an electron because it lost an electron to NADPH

• as H⁺ move back across the membrane, they make lots of ATP

Calvin Cycle reactions

• energy of ATP and NADPH are used to make glucose (carbohydrate) from carbon dioxide
• take place in the chloroplast stroma

© Carol L. Wymer, 2004