Lab 7: Photosynthesis 10/27/2015

Basics of Photosynthesis Photosynthesis: process that transforms light energy into chemical energy. occurs on land and in water performed by autotrophic plants, algae, and bacteria

Formula of photosynthesis Inputs:Products: 6 O2 oxygen gas C6H12O6 glucose 6 CO2 carbon dioxide 6 H2O water Formula of cellular respiration: (from last week) Inputs:Products: 6 CO 2 carbon dioxide 6 H 2 O water 6 O 2 oxygen gas C 6 H 12 O 6 glucose Nature Recycles: Photosynthesis and Cellular respiration are opposites: Each one takes the products of the others reactions and uses it for inputs. 6 O 2 oxygen gas C 6 H 12 O 6 glucose 6 CO 2 carbon dioxide 6 H 2 O water

Photosynthesis: Road Map Photosynthesis can be divided into two parts: 1.Light Reactions 2.Dark Reactions Light reactions: convert solar energy to chemical energy. Dark reactions: convert chemical energy and carbon dioxide into sugars

Photosynthesis: light reactions (convert solar energy to chemical energy.) Different colors of light are different wavelengths with different energies. Inputs: Light and Water Products: O 2 Chloroplasts are organelles that absorbs light in plant tissue. Green color in chloroplast comes from chlorophyll – light absorbing pigment. thylakoids which are membranous sacs forming stacks called grana. Chloroplast Thylakoids form stacks called grana So why are plants green? Chloroplasts and chlorophyll

Photosynthesis: dark reactions / Calvin cycle (convert chemical energy & carbon dioxide into sugars.) This part is called a dark reaction because it can happen with or without light. Input:CO 2 Product:glucose Stroma is a thick fluid within chloroplast, this is where enzymes associated with dark reactions occur. Chloroplast

Photosynthetic Pigments Part A: 2. Remember: chlorophyll is a light absorbing pigment. However most chloroplasts contain 4 or more different pigments. These pigments show up as the different colors in fall leaves. Paper Chromatography: Allows us to separate out each pigment based on molecular size. Smaller pigments travel further up the paper than larger ones. We can identify the pigments by color.

Photosynthesis: Light Reaction Part A: 3. As part of the light reaction, oxygen is produced from water. Volumeter 3% sodium bicarbonate (NaCO 3 ) 2-3 fresh Elodea sprigs, cut end up. Beaker filled with water – heat absorber Light source Mark the solution front on the glass tube initially and when you first notice movement start timing 10 minutes. After 10 minutes mark front again and measure the distance in mm. water

Photosynthesis: Light Reaction Part A: 3. Then carefully pick up tube being sure not to disturbing the stopper or bent tube. Wrap the tube in aluminum foil. Place back into the light. Wait 10 minutes and mark where the front is, then measure the distance in mm. Volumeter 3% sodium bicarbonate (NaCO 3 ) 2-3 fresh Elodea sprigs, cut end up. Wrap in aluminum foil. Beaker filled with water – heat absorber Light source water

Uptake of Carbon Dioxide Part B Blow into straw Add a sprig (or several) of Elodea to one of the test tubes – make sure it is alive! Stopper both tubes. Beaker filled with water and phenol red (red = basic). CO 2 + H 2 O → H 2 CO 3 → H + + HCO 3 − Yellow = acidic

Uptake of Carbon Dioxide Part B Monitor any color change over time. Swirl the tubes occasionally. Beaker filled with water – heat absorber Light source water Place the test tubes in the test tube rack with the tube from Part A.3

To do: Lab reports Visual aid for bioethics presentations will be due in 2 weeks – “Visual aids are due before the beginning of class the week of Nov. 4. So if you have Thursday lab at 12:00 pm on Nov 7, it’s due Thurs, Nov. 7 at 11:59 am. You may your electronic slide to In addition, please bring to class a copy of your visual aid on a thumb drive on the day you present.” Research paper topics – due next week on quiz!! For quiz: – What are inputs and outputs of cellular respiration? Photosynthesis? Know the formulas! – What is the purpose of the light reactions? The dark reactions? Why are they called light and dark reactions, respectively? – What happened to the water in the volumeter in part A 3 when the Elodea was in the light? In the dark? WHY? Be sure your answer to ‘why’ is in terms of the inputs and products of photosynthesis and respiration. – What happened to the color of the acidified solution in part B when Elodea was photosynthesizing? WHY? Be sure your answer to ‘why’ is in terms of the inputs and products of photosynthesis.