‘The light at the end of the tunnel’ Photosynthesis ‘The light at the end of the tunnel’

A two step process Light STEP 1 = Light dependent stage (red and blue wavelengths absorbed, green reflected) pigment chlorophyll, hydrogen and CO2 STEP 1 = Light dependent stage (requires light) STEP 2 = Light independent stage

Structures Chloroplast The structure where photosynthesis takes place. See Biozone pg 299 Chloroplast The structure where photosynthesis takes place. Inside the chloroplast: Grana – membranes that contain the pigment chlorophyll (site of light dependent stage) Stroma – liquid inside chloroplast (site of light independent stage = Calvin cycle)

Step 1 Light dependent stage (energy capture): The light strikes chlorophyll and creates a series of reactions, the energy is converted into ATP (photophosphorylation) and NADPH. Water is split in the process releasing O2. Occurs in the Grana

Step 2 Light independent stage (carbon fixing): CO2 from the atmosphere or water is captured and modified by the addition of hydrogen to form carbohydrates (carbon fixing). Energy to do this comes from step 1. The Calvin cycle allows for carbon fixing to occur. Six CO2 molecules enter the Calvin cycle, eventually producing 1 glucose. Occurs in the stroma.

Light independent stage ATP and ADP (ATP) Light dependent stage NADPH (ADP) Light independent stage NADP

Cellular respiration Then the process of cellular respiration occurs using the glucose produced by photosynthesis. Plants carry out cellular respiration so energy is released for all of their metabolic reactions.

Questions _______ and ________ wavelengths are absorbed by chlorophyll. The energy capture stage of photosynthesis occurs where in the chloroplast ____________ . Carbon fixing stage of photosynthesis occurs where in the chloroplast ______ . In which stage is water split ________ ____________

Questions cont…. 5) Why are most photosynthetic organisms green __________________________ . 6) In stage two where does the CO2 come from _______________ and _________ . 7) What is the importance of the Calvin cycle in relation to respiration _____________ . 8) Why is photosynthesis fundamental to life _________________________________