ET #58: What do plants need to make (their own) food? Light Energy Carbon dioxide Water ET #58: What is this food? Glucose (C6H12O6) Today’s Learning Target I can: Identify the reactants and products in Photosynthesis. Ch 7: Cells are Busy Places Lab: Cellular Activities in Plants (Photosynthesis) lab intro design lab create data table Converting Sunlight into Sugar What is Photosynthesis? photo = light synthesis = put together CO2 + water Reactants light chlorophyll glucose + O2 Products CO2 (from air) O2 Oxygen H2O (from ground) Glucose (food, growth) Light Put Together Chlorophyll + Bromothymol Blue = BTB • Do Activity Part 1: Goggles MUST BE WORN! • BTB is a chemical that changes color in the presence/absence of CO2 • CO2 in water = carbonic acid (a weak acid). This changes blue (basic) solution to yellow (acidic). • If CO2 is used up (by photosynthesis), yellow will changes to green then blue. BTB CO2 Absent Carbon Dioxide Present Each group will be assigned two distances. We will share the class data. Your Experiment: H2O+ BTB + CO2 Put near light at specific distances Variables? Amounts? (mL) Distances? (cm) Rate? (sec) BTB solution turns yellow Add Elodea leaf O2 Glucose Oxygen Evidence? Questions: •How long will this take? •How will I know photosynthesis is happening? Is photosynthesis happening? How do I know if photosynthesis is happening? O2 Bubbles! Air bubbles appear on the leaves of the plant Plant is giving off O2! O2 bubbles forming on Elodea leaves Bubbles! Activity II: Photosynthesis Inquiry Lab Question: Does the intensity of light affect the rate of photosynthesis in Elodea leaves? light intensity = distance (cm) from light source rate = time (minutes/sec) Manipulated var: _?___ Responding var: _?___ Evidence of photosynthesis? • Presence of bubbles (O2) on leaf Hypothesis: If…(MV), then….(RV), because… (Make a Prediction as to what will happen and why) •Materials: Include what materials you plan to use* *You have the materials listed: 2 beakers, 6 test tubes, etc. You will also have a sheet of black paper •Write a detailed Procedure (minimum 10 #’d steps) •Need to design a Controlled Experiment (Do you trust the data? What can you do to ensure the MV is what’s causing your results? ) •Set up a Data Table with headings **These things must be done in order to start lab!** What should your data table look like? How many columns? How many rows? What should your data table look like? How many columns? How many rows? Each group will be assigned two distances from the light source (i.e., two different light intensities) highlighted in yellow. Some groups will be assigned a control group. Data (time it takes for bubbles to first appear on leaves) will be recorded on the shared “class data” spreadsheet in Google Docs. Procedure should includes steps to collect photosynthesis rate data for all five distances (5 light intensities) and a control group even though your group will only be assigned two of the distances, plus the control. We are sharing the data collected as a class.