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Photosynthesis

6CO 2 + 6H 2 0  C 6 H 12 0 6 + 6O 2 Reactants yield Products. Photosynthesis. Photosynthesis . Involves concepts from . Biology. Physics. Chemistry. Organisms exist because of chemical reactions occurring within cells.

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Photosynthesis

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  1. 6CO2 + 6H20  C6H1206 + 6O2 • Reactants yield Products Photosynthesis

  2. Photosynthesis • Involves concepts from Biology Physics Chemistry

  3. Organisms exist because of chemical reactions occurring within cells. • Chemical reactions occur in all cells, tissues, organs, and organ systems. Digestive System

  4. What is a chemical reaction? • Atoms or ions are • joined together by chemical bonds (forming a compound) OR • compounds are broken apart • All chemical reactions involve a rearrangement of atoms or ions AND

  5. Energy

  6. Chemical Reactions • Example of a reaction: 2H2 + O2  2H2O • A molecule of hydrogen is made up of 2 hydrogen atoms held together by high energy bonds. • A molecule of oxygen is made of 2 oxygen atoms held together by high energy bonds.

  7. Chemical Reactions 2H2 + O2  2H2O • Water is formed when molecules of hydrogen and molecules of oxygen are broken AND • Atoms rearrange themselves into molecules of water held together with low energy bonds.

  8. Chemical Reactions 2H2 + O2  2H2O HIGH ENERGY BONDSLOW ENERGY BONDS REACTANTS PRODUCTS + Energy All of the extra energy found on the reactant side of the equation is released with the product as heat or light.

  9. Law of Conservation of Energy • Energy cannot be created or destroyed, however it can change forms. • In our example: If the reaction is reversed… • Energy must be added to water to break it down. This added energy ends up stored in chemical bonds of hydrogen and oxygen molecules.   2H2O + Heat ENERGY 2H2 + O2 •  Energy can be stored for later use. Worksheet: chemical reactions and energy

  10. Chemical Reaction-Formation of Water +

  11. Forms +

  12. Physics • White light is made up of a spectrum of colors.

  13. Physics • The spectrum is seen when the white light is broken up into its components by prisms or raindrops*

  14. Light • Whenallcolorswithinwhitelightarereflectedbackto oureyesweseeWHITE! • Whenallcolorswithinwhitelightareabsorbedby an objectweseeBLACK! • A surface appears a particular color because it contains a "pigment" that reflects that particular color and absorbs all other colors. • Pigment = light absorbing colored molecule

  15. Name the color • What is the color of a sweater that absorbs blue, green and yellow light?

  16. What colors are absorbed by Green Plants?

  17. Green Plants • Reflect green light • Absorb all other colors of light

  18. Green Plants

  19. Biology • Organisms make their own food and are called autotrophs

  20. Or • Organisms EAT plants or animals and are called __________________________________ heterotrophs

  21. Biology • Autotrophs use light energy from the sun (or chemical energy) to produce energy rich sugars/carbohydrates. Examples of autotrophs: _____________________,________________, ____________________________ green plants some protista some bacteria • Energy in most ecosystems on earth comes from

  22. Early Scientific Research on Photosynthesis • 1643 – Belgium • Jan van Helmont • With your group: analyze van Helmont’s experiment

  23. Conclusions from van Helmont’s experiment • “…164 pounds of wood, bark, and roots had arisen from water alone.” The mass of the tree did NOT come from the soil. • Was van Helmont correct? _____________________ Partially correct • The mass of a plant comes in part from water…NOT from soil (except for a tiny fraction) • Plants are made of carbohydrates. The term “hydrate” = water.

  24. Late 1700’s EnglandJoseph Priestley • Joseph Priestley discovered oxygen in 1774 • He continued to experiment with gases, plants and animals. With your group analyze Priestley’s experiment!

  25. Priestley’s Photosynthesis Experiment • Priestley concluded green plants produce the substance “oxygen” necessary for a fire to burn and for animal’s to breathe.

  26. Late 1700’s Jan Ingenhousz’s • Jan Ingenhousz was born in 1730 in the Netherlands. He trained as a medical doctor. • In 1779, Ingenhousz took a position in the same laboratory as Joseph Priestley. • Ingenhousz carried out research on photosynthesis.

  27. Ingenhousz’s Photosynthesis Experiment • Ingenhousz placed a pond plant in a jar filled with water • He placed the jar in bright sunlight and observed bubbles producedby the plant • He placed the jar in low light conditions and observed no bubbles produced by the plant

  28. Ingenhousz’s Conclusion • Green plants only produce oxygen in the presence of _______________. Sunlight

  29. Photosynthesis • By the mid-1800’s, it was understood that plants produce glucose (carbohydrates) and oxygen using light energy and carbon dioxide and water.   • Photosynthesis Reaction: • 6CO2 + 6H2O +  C6H12O6 + 6O2

  30. Photosynthesis • CO2 enters plants through stomata in leaves and stem. • O2 and water exit the stomata

  31. Carbon Dioxide

  32. Water • H2O enters plants through roots and is carried by the veins to leaves Water travels through the plant’s xylem (upward veins) from the roots to the leaves

  33. Products of Photosynthesis • Glucose and Oxygen • Glucose is carried from the leaves of the plant in phloem (downward veins) to the parts of the plant where photosynthesis does not occur (roots, flowers). • Glucose is stored in fruits (apples, oranges, etc.) and roots (onions, potatoes, etc.) • Oxygen is released from stomata.

  34. Photosynthesis • Complete worksheet on Green Plants!

  35. What else is needed for Photosynthesis? • Photosynthesis occurs in the chloroplasts of plant cells.

  36. Chloroplasts are made of • thylakoids – sac-like membranes containing molecules of chlorophyll, a pigment, which absorbs red and blue light. • stroma– space outside of the thylakoids

  37. If plants contain chlorophyll why do they turn color in the fall?

  38. Processes of Photosynthesis • Two Stage process: • Light DEPENDENT reaction and • Light INDEPENDENT reaction or CALVIN CYCLE

  39. LIGHT DEPENDENT REACTION • Occurs only in light! • Takes place in thylakoid • A) H2O enters chloroplast (through xylem) • B) Bonds holding H2O together are broken and H+ and oxygen atoms are produced • C) H+ ions are used in making glucose. • C)O2 is released through stomata. This is the oxygen we breathe.

  40. Light Dependent Reaction (cont) • Light energy enters the thylakoid in the plant’s chloroplasts. • This energy is converted into chemical energy and is stored in two chemical compounds: • ATP (Adenine Triphosphate) • NADPH (Nicotinamide Adenine Trinucleotide Phosphate) • Note: The light energy hasn’t been created or destroyed by the plant, but it has changed forms.*

  41. Fact Check – Light Dependent Reaction • In which part of the chloroplast does the light dependent reaction occur? • Which two high energy molecules are produced using the light energy from the sun? • What is the “waste product” of the light dependent reaction? • How does this waste product exit the plant cells? • Which part of the water molecule is used to make a molecule of glucose? • What is the role of sunlight in the process of photosynthesis?

  42. Light Independent Reaction or Calvin Cycle • Occurs in stroma – the space surrounding the thylakoid membranes • Takes place in light OR dark

  43. Light Independent Reaction or Calvin Cycle • CO2 enters chloroplasts through stomata. • Energystored during the light dependent reaction (ATP and NADPH) is used to convert the Carbon dioxide + the Hydrogen ions (from water) into glucose.*

  44. Light Independent Reaction or Calvin Cycle Chemical Energy in ATP + NADPH H+ + CO2 Glucose Low energy bonds in CO2 High energy bonds in glucose Low energy ADP + NADP+ (Available for light dependent reaction)*

  45. Photosynthesis Equation! • 6CO2 + 6H20  C6H1206 + 6O2 Reactants Products

  46. Fact Check – Light Independent Reaction • In which part of the chloroplast does the light independent reaction occur? • What is another name for the Light Independent Reaction? • Why is it called the Light Independent Reaction? • Which molecule is added to H- (from the light dependent reaction) to make glucose? • How does the molecule referred to in #4 enter the chloroplast? • Which molecule is used to provide the chemical energy for the high energy bonds holding glucose molecules together?

  47. Factors affecting Photosynthesis • Light - Absence of light  no photosynthesis • Increase in light intensity increases rate of reaction (up to a point—this point is dependent on the particular species of plant) • Water - Absence of water slows or stops the process • Temperature – Occurs at 0­°C 35°C (32°F – 95°F) Would you expect a shortage of CO2 to be a problem for plant growth on earth? Why or why not?

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