Chapter 8a Photosynthesis Mr. Karns biology To add to Make these your notes! Have out your derivational terms sheet and a blank sheet of paper Blinded by the light elo Photosynthesis & Cellular Respiration Cycle Photosynthesis (daylight only, in presence of chlorophyll) Respiration (all the time, aerobic and anaerobic) CO 2 H2OH2O ATP Glucose O2O2 CA Standard you should get from today: biology: 1 f students know usable energy is captured from sunlight by chloroplasts and is stored through the synthesis of sugar from carbon dioxide Stand up- alternate statements to your neighbor quietly say it outloud Plants use sunlight energy to fix energy into chemical bonds of sugar. It takes light, water and carbon dioxide to do this. It happens in a chloroplast of a leaf 1. Light reaction requires light, 2. the other does not (but requires the first reaction to happen). How do the raw materials get into the leaf? Water- comes to the leaves from the roots (vascular tissue) Carbon Dioxide- through the stomata underside of the leaves O 2 exits through the stomata Stomates in a C4 plant regulating carbon dioxide & water loss Copy this summary of photosynthesis on your notebook paper (quickly) First - light reactions in the (thylakoids) Photolysis- splits water releases oxygen Makes some intermediate molecules that go into the next reactions (NADPH and ATP) oxygen O 2 given off as a waste product ThenLight Independent reaction- (dark reactions) builds the sugars from the products of the light reactions. This is when the carbons are fixed into the glucose. Energy Is the ability to do work (physiological work) Is provided to organisms in the form of chemical bonds in food molecules (ex. carbohydrates, fats, proteins) Foods are slow to provide energy to cells They have to be digested/processed first A fast energy source is stored in the chemical bonds of ATP Historical experiment by Joseph Priestly So- what did the experiment show? Anything with carbon dioxide? Plants give off something the candle and the mouse need. It did not show that light was necessary, it did not test for carbon dioxide. It did not test for water. It only showed. other famous plant experiments Overall reaction equation: Carbon dioxide and water reacts to form sugar and oxygen in a leaf ( with sunlight) CO 2 + H 2 O > C 6 H 12 O 6 + O 2 + H 2 O [Reactants] [Products] CO 2 comes from the atmosphere, (goes into the leaf) H 2 O comes from the ground water (via roots) Balanced- it looks like this. 6CO H 2 O -----> C 6 H 12 O 6 + 6O 2 +6H 2 O Notice the atoms on the left = total atoms on the right What goes in equals what comes out So- how many water molecules does it take to make 1 glucose; C 6 H 12 O 6 ? Tell your neighbor quietly Today - what we know of Photosynthesis Watch where the atoms go, from reactants to products Only the visible spectrum can be absorbed in photosynthesis Invisible Things that can happen to light Absorbed, transmitted or reflected Chlorophylls a, b (c, d found in algae) Accessory pigments (other colors) - carotenoids (yellow-orange) - xanthophyll (yellow) - fucoxanthin (brown) - phycobilins (green, violet and blue) These absorb colors not absorbed by chlorophylls Ring portion absorbs the light rays Pigment molecules All these pigments work together to capture the energy in sunlight. They are called antenna pigments as they work like an antenna to pick up the energy from various wavelengths. You are the sunshine of my life Stevie Wonder ATP Adenosine triphosphate A P ~ P ~ P+ P (phosphorylated molecule -- energized; can now do cellular work by passing along energy received from binding to P from ATP) P i from cytoplasm A P ~ P (ADP) ~ = high-energy bond = mitochondrion = protein molecule (ex. transport protein) Review of ATP/ADP Light reactions ( some details) this is hung under podcasts on my CHS page watch it again from home! Terms Chloroplast Thylakoid Granum or Grana (pleural) Stroma Grana means stack of coins in Latin ! Chloroplast Stoma (opening in leaf; CO 2, O 2, H 2 O) Mesophyll (Part of leaf with chloroplasts) What happens to the water? Does oxygen of H 2 O become part of glucose or go to the atmosphere? Experimentally proven: Make oxygen of H 2 O radioactive with isotope 18 O so that it can be traced through the photosynthesis reactions. CO 2 + H 2 18 O > C 6 H 12 O O 2 This shows H 2 O becomes split during the reactions. (hydrolysis) New question? How does H and its energy become part of glucose? Answer involves a hydrogen-carrier molecule NADP. Copy this summary First part - light reactions in the (thylakoids) Photolysis- splits water releases oxygen Makes some intermediate molecules that go into the next reactions (NADPH and ATP) oxygen O 2 given off as a waste product Light Independent reaction- (dark reactions) builds the sugars from the products of the light reactions. This is when the carbons are fixed int the glucose. Details- light- antennae pigments (clusters of pigment molecules) All pigment molecules can absorb different light energies, but only one molecule can send an excited electron to the primary electron acceptor -- that one must be a chlorophyll molecule. Thylakoids (flat sacs stacked into a granum) Photosystem (collection of pigment molecules) Details of a thylakoid Two sets of photosynthesis reactions occur in the chloroplast Light-dependent - in the thylakoid membrane Light-independent - in stroma (thick liquid between thylakoids) Stroma Light-dependent Reactions Electron transfer chain Released energy is used to make: Begins with high-energy (excited) electrons. 1. Split H 2 O -----> H + + O 2 (escapes to atmosphere) NADP > NADPH 2. ADP + P i > ATP These are used in the light-independent reactions The light independent reactions or the dark reactions for us old school guys Dark Reactions or Calvin Cycle Dont get hung up on the words, just get the idea! Hey.- wake up, we are just building a 6 carbon sugar called glucose! Another look at the dark reactions- Stand up- alternate statements to your neighbor quietly say it outloud Plants use sunlight energy to fix energy into chemical bonds of sugar. It takes light, water and carbon dioxide to do this. It happens in a leaf and involve two reactions 1. Light reaction requires light, 2. the other does not (but requires the first reaction to happen). Spot check- whisper to your neighbor, then raise your hand if you know the answer. Question 1 Why do plants require oxygen? A.for photolysis B.for aerobic respiration C.for glycolysis D.to carry out the Calvin cycle Hint- this was said orally. Question 2 Which of the following environmental factors would influence the rate of photosynthesis within a plant? A. color of light B. intensity of light C. concentration of C0 2 in the surrounding air D. A, B, and C Question 3 A test tube of chloroplasts was exposed to various colors of light, and the rate of photosynthesis was measured. What factor was being tested? A. the effect of light on photosynthesis B. the effect of color on the rate of photosynthesis C. whether chloroplasts can carry out photosynthesis in isolation D. whether or not chloroplasts are alive Question 4 Why would astronauts consider taking plants on long space flights? A. Plants would produce both sugars and oxygen. B. Plants would digest organic waste products produced on the spaceship. C. Plants would act as cooling agents on the spaceship. D. Plants would produce light for the spaceship. Question 2 Plants below the canopy in the tropical rain forest usually have large broad leaves. Why? A.They help the plant collect water. B.They help the plant collect oxygen. C. They help the plant digest sugars. D. They help the plant collect light. How many carbon dioxide molecules must be present to build 1 glucose molecule? How many oxygen atoms will be released from the building of a single glucose molecule? 6CO H 2 O ---> C 6 H 12 O 6 + 6O 2 +6H 2 O Margin a drawing paper to form. Use pencil, rulers. Day 2 Get a scope 1 per 2 students 1. Make a wet mount of the underside of a leaf. 2. Use scanning, low then high power to observe and locate a stomata. 3. Draw it under low and high power 4. Label the guard cells and the stomate opening.