Photosynthesis Chapter 8 E N E R G Y T O M A K E F O O D?

Transcription

1 Photosynthesis Chapter 8 H O W D O E S T H E P L A N T U S E T H E S U N S E N E R G Y T O M A K E F O O D?

2

3 Autotroph vs. Heterotroph Autotrophs/Producers-organisms that make their own food. Plants and other types of organisms use light energy (sun) to produce food. Heterotrophs/Consumers-obtain energy from foods they consume. Animals, fungi, and some protists

4 Energy 3 types Potential Kinetic Radiant

5 Potential stored energy Based on position of an object or energy that is found in chemical bonds Batteries, Food

6 Kinetic Energy energy that moving objects/particles have

7 Radiant Energy in the form of light

8 Law of Conservation of Energy

9

10 An overview of Photosynthesis Van Helmont Priestly Ingenhousz

11 Van Helmont (1643) Jan van Helmont s Experiment Determined mass of soil and seedling Watered every day for 5 years Mass of soil did not change plant gained 75 kg Conclusion: plants incorporate water into themselves, water accounted for most of mass increase, the remaining was carbon dioxide uptake from air.

12 Joseph Priestley (1771) Using a bell jar, a candle and plant he found that plant s release a substance that keeps a candle burning. Conclusion: Plants release oxygen

13 Jan Ingenhousz (1779) Found that Priestleys experiment only worked when the plant was exposed to light. Conclusion: Plants need light to produce oxygen

14 Overall Conclusion In presence of light (energy) plants transform carbon dioxide (CO 2 ) and water (H 2 O) into carbohydrates (like glucose=c 6 H 12 O 6 ) and release oxygen (O 2 ).

15 6CO 2 + 6H 2 O C 6 H 12 O 6 + 6O 2 Chlorophyll (pigment) in the chloroplast absorbs the suns energy Looking at Figure 8-5

16 Which color of light energy is absorbed? Which is reflected?

17 How do plants convert light into food? Gather sun s energy using light absorbing molecules called pigments. The principal pigment is chlorophyll. Chlorophyll a and Chlorophyll b

18 Notice that green light is reflected! What does that explain to you?

19 *Remember that light is a form of ENERGY! So when light is absorbed, so is energy.

20 esis.swf

21 Anatomy of a chloroplast Thylakoids: saclike photosynthetic membranes; arranged in stacks called grana. Contains the pigment chlorophyll Stroma: space outside the thylakoid membrane

22 How does photosynthesis work? Electrons from absorbed energy power photosynthesis Takes place in a chloroplast Proteins in the thylakoid membrane organize chlorophyll into clusters called photosystems. Reactions of photosystems in 2 parts

23 Photosynthesis: An overview Similar to Figure 8-7

24 2 parts to photosystem reaction: Step 1: Light dependent reaction Takes place in the thylakoid membranes Step 2: Calvin cycle (dark reaction) Takes place in the stroma Remembering: Where is the stroma?

25 Figure 8-7 Photosynthesis: An Overview Light H 2 O CO 2 Chloroplast Chloroplast NADP + ADP + P Light- Dependent Reactions ATP NADPH Calvin Cycle Pg. 209 Some Questions O 2 Sugars

26 Figure 8-10 Light-Dependent Reactions- Uses energy from sunlight to produce ATP, NADPH, and oxygen. (Converts ADP and NADP + into fully charged batteries.) Photosystem II Hydrogen Ion Movement ATP synthase Chloroplast Inner Thylakoid Space Thylakoid Membrane Pg. 211 Some Questions Stroma Electron Transport Chain Photosystem I ATP Formation

27 Figure 8-11 Calvin Cycle-Uses ATP and NADPH to produce high-energy sugars. (Sends back ADP and NADP + to light reaction for recharging.) CO 2 Enters the Cycle Energy Input ChloropIast 5-Carbon Molecules Regenerated 6-Carbon Sugar Produced Sugars and other compounds

28 Factors that affect photosynthesis Amount of water How do plants live in dry temperatures? Temperature Depends on enzymes that work best between 0 o C and 35 o C Above or below these temperatures will cause the slowing of photosynthesis At very low temperatures, photosynthesis may stop Amount of light Increasing light will increase photosynthesis, however at a certain point, it will reach its maximum rate of photosynthesis

29 Life without light Some autotrophs can produce food without light. Rely on energy from inorganic molecules. Called chemosynthesis Performed by many bacteria

30 Comparing What is the difference between photosynthesis and chemosynthesis?

31 alvin.htm