Photosynthesis

1. Photosynthesis + 6H2O+ 6CO2 C6H12 O6+ 6O2 Reactants Products Light Energy + Water + Carbon Dioxide yield Glucose + Oxygen

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

3. 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? _____________________ • 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. Partially correct

4. 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!

5. Priestley’s Photosynthesis Experiment • Priestley concluded green plants produce “oxygen”, which isnecessary for a fire to burn and animals to breathe.

6. 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.

7. 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

8. Ingenhousz’s Photosynthesis Experiment • Ingenhousz knew the bubbles produced by plants are made of oxygen gas. • He concluded that oxygen is only produced if the green plant is in the presence of __________. Light

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

10. 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

11. Name the color • What is the color of a sweater that absorbs blue, green and yellow light? (Hint: Which color is NOT absorbed but instead must be reflected?) Which color is reflected by this sweater?

12. Name the color • What is the color of a pair of jeans that absorbs all colors of the rainbow? Which color is reflected by the jeans? NONE!

13. What colors are absorbed by Green Plants?

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

15. Green Plants

16. Photosynthesis • If organisms make their own food they are called autotrophs

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

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

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

20. Carbon Dioxide

21. 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

22. 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.

23. Photosynthesis • Complete worksheet on Green Plants!

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

25. 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

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

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

28. LIGHT DEPENDENT REACTION • Occurs only in light! • Takes place in the thylakoid  this is where chlorophyll is found

29. Light Dependent Reaction • H2O enters the thylakoid • Chemical bonds holding H2O together are broken and H+ and oxygen molecules are released Water H+ + O2 • H+ ions are used in making glucose. • O2is released through stomata. This is the oxygen we breathe.

30. Light Dependent Reaction (cont) • Light energy enters the thylakoid • This energy is converted into chemical energy and is stored in two chemical compounds: • ATP (Adenine Triphosphate) • NADPH • Note: The light energy hasn’t been created or destroyed by the plant, but it has changed forms. • TO DO: Complete Light Dependent Reaction section of Photosynthesis Worksheet!

31. 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 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? thylakoid ATP and NADPH oxygen stomata Hydrogen ions Produces ATP

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

33. Light Independent Reaction or Calvin Cycle • CO2 enters chloroplasts through stomata. • Energy stored during the light dependent reaction (ATP and NADPH) is used to convert CO2+ H+ (from water) into C6H12O6 (glucose.)

34. Light Independent Reaction or Calvin Cycle TO DO: Complete Photosynthesis Worksheet! Chemical Energy in ATP + NADPH H+ + CO2 Glucose Low energy bonds in CO2 High energy bonds in glucose

35. 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? stroma Calvin Cycle Occurs with or without sunlight CO2 stomata ATP

36. Factors affecting Photosynthesis • Light - Absence of light  no photosynthesis

37. Factors affecting 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

38. Factors affecting Photosynthesis 4. Temperature – Photosynthesis does NOT occur if it is below the freezing point (0°C or 32°F) or above 35°C/95°F. Would you expect a shortage of CO2 to be a problem for plant growth on earth? Why or why not?

39. Environmental Factors Affecting Photosynthesis • Complete worksheet “Energy in a Cell”: Critical Thinking and Problem Solving