How does a seed grow into a tree? Where does all the mass come from???

1. How does a seed grow into a tree? Where does all the mass come from???

2. Photosynthesis

3. Plants convert the energy of sunlight into the energy of chemical bonds of carbohydrates

4. Importance of Photosynthesis

5. But that’s not all..

7. But wait, there’s more..

8. Photosynthesis: 6 CO2 + 6 H2O C6 H12 O6 + 6 O2 carbon dioxide + water = sugar + oxygen • photosynthetic products often stored as starch • Starch = glucose polymer STARCH

9. Sun CO2+H20 C(H2O)+ O2 Photosynthesis Respiration The BIG Picture

10. Leaf Structure cuticle - waxy, water resistant layer on the surface of the leaf Epidermis - transparent, colourless cell layer below the cuticle mesophyll cells - pallisade: are elongated cells located just below the epidermal tissue - spongy mesophyll consists of loosely packed cells where gas exchange takes place

11. Fig. 10.2a

12. Leaf structure

13. Chloroplasts

14. Fig. 10.2b

15. Chloroplasts • plant cell organelles where photosynthesis takes place, found mainly in mesophyll layers in leaves • have an inner and outer membrane • the liquid material in the chloroplast is called the stroma • Stroma contains a series of membrane bound sacs called thylakoids which are stacked on top of one another to form grana • adjacent grana are linked together by lamellae

16. Photosynthesis occurs partly within the stroma and partly within the thylakoid membrane • The thylakoid membrane contains light-gathering pigments and an electron transport chain • Thylakoid membranes enclose an interior space called the thylakoid lumen

17. Overview of Photosynthesis 1. Light reactions 2. Dark reactions – Calvin Cycle

18. Fig. 10.4

19. When light strikes an object it can be: • Reflected • Transmitted • Absorbed • Substances that absorb light are called pigments • Different pigments absorb at different wavelengths

21. Pigments

22. Chlorophyll • Chlorophyll is a pigment that absorbs in the red and blue regions of the visible spectrum • Most of the green wavelengths are reflected so a sample of chlorophyll appears green

23. Chlorophyll • Absorbs red & blue light • Reflects green light

24. Fig. 10.6

25. Fig. 10.8

26. Energy Storing Compounds Energy trapped by molecules can be used to lift electrons to a higher energy level. From that higher energy level the electrons can fall down to their original energy level and do work along the way. Example – a solar cell that powers a calculator

27. Or… The high-energy electrons can be bound to an electron carrier. Nicotinamide Adenine Dinucleotide Phosphate NADP+ accepts a pair of high energy electrons and a Hydrogen ion to become NADPH

30. And of Course ATP – Adenosine Triphosphate Energy storing compound used by every living cell Provides the energy for almost all cellular functions

31. Function of ATP

32. Light Reactions

33. Calvin Cycle Products from the light reactions and CO2 from the atmosphere are used to produce carbohydrates

37. Autotrophs • Self-feeders: • sustain themselves without eating or decomposing other organisms • Plants are photoautotrophs • They use light • Some bacteria are chemoautotrophs • Produce organic compounds without light from substances such as S or NH3

38. Heterotrophs • Live on compounds produced by other organisms • Eat other plants or animals or are decomposers (bacteria or fungi) that eat fallen leaves, feces, dead animals