Presentation on theme: "Photosynthesis + 6H 2 O + 6CO 2 C 6 H 12 O 6 + 6O 2 Reactants Products Light Energy + Water + Carbon Dioxide yield Glucose + Oxygen."— Presentation transcript:
Photosynthesis + 6H 2 O + 6CO 2 C 6 H 12 O 6 + 6O 2 Reactants Products Light Energy + Water + Carbon Dioxide yield Glucose + Oxygen
Early Scientific Research on Photosynthesis 1643 – Belgium Jan van Helmont With your group: analyze van Helmont’s experiment
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
Late 1700’s England Joseph Priestley Joseph Priestley discovered oxygen in 1774 He continued to experiment with gases, plants and animals. With your group analyze Priestley’s experiment!
Priestley’s Photosynthesis Experiment Priestley concluded green plants produce “oxygen”, which is necessary for a fire to burn and animals to breathe.
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.
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 produced by the plant He placed the jar in low light conditions and observed no bubbles produced by the plant
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
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: 6CO 2 + 6H 2 O + C 6 H 12 O 6 + 6O 2
Light When all colors within white light are reflected back to our eyes we see WHITE! When all colors within white light are absorbed by an object we see BLACK! 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*molecule
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?
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!
Photosynthesis If organisms make their own food they are called autotrophs
Or Organisms EAT plants or animals and are called __________________________________ heterotrophs
Photosynthesis Autotrophs use light energy from the sun (or chemical energy) to produce energy rich sugars/carbohydrates. Examples of autotrophs: _____________________,________________, ____________________________ some protistagreen plants some bacteria Energy in most ecosystems on earth comes from
Photosynthesis CO 2 enters plants through stomata in leaves and stem. O 2 and water exit the stomata* stomata
Water H 2 O 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
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.
Photosynthesis Complete worksheet on Green Plants!
What else is needed for Photosynthesis? Photosynthesis occurs in the chloroplasts of plant cells. Chloroplast
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
If plants contain chlorophyll why do they turn color in the fall? Some plants contain pigments that reflect yellow and red. In the fall, the chlorophyll pigment breaks down, and the other colors are revealed!
Processes of Photosynthesis Two Stage process: Light DEPENDENT reaction and Light INDEPENDENT reaction or CALVIN CYCLE
LIGHT DEPENDENT REACTION Occurs only in light! Takes place in the thylakoid this is where chlorophyll is found
Light Dependent Reaction H 2 O enters the thylakoid Chemical bonds holding H 2 O together are broken apart and H + and oxygen molecules are released Water H + + O 2 H + ions are used in making glucose. O 2 is released through stomata. This is the oxygen we breathe.
Light Dependent Reaction (cont) Light energy enters the thylakoid This energy is converted into chemical energy and is stored in two chemical compounds: ATP (Adenosine Triphosphate) converted by light energy from ADP (low energy) NADPH converted by light energy from NADP + (low energy) Note: The light energy hasn’t been created or destroyed by the plant, but it has changed forms. TO DO: Complete a-m Light Dependent Reaction section of Photosynthesis Worksheet!
Fact Check – Light Dependent Reaction (p. 4) 1. In which part of the chloroplast does the light dependent reaction occur? 2. Which two high energy molecules are produced using the light energy from the sun? 3. What is the “waste product” of the light dependent reaction? 4. How does this waste product exit plant cells? 5. Which part of the water molecule is used to make a molecule of glucose? 6. What is the role of sunlight in the process of photosynthesis? thylakoid oxygen stomata Hydrogen ions Produces ATP ATP and NADPH
Light Independent Reaction or Calvin Cycle 1. Occurs in stroma – the space surrounding the thylakoid membranes 2. Takes place in light OR dark
Light Independent Reaction or Calvin Cycle 3. CO 2 enters chloroplasts through stomata. 4. Energy stored during the light dependent reaction (ATP and NADPH) is used to convert CO 2 + H + (from water) C 6 H 12 O 6
Light Independent Reaction or Calvin Cycle ATP (high energy molecule) ADP (low energy molecule) NAPDH (high energy molecule) NADP + (low energy molecule TO DO: Complete n-v Light Dependent Reaction section of Photosynthesis Worksheet! Chemical Energy in ATP + NADPH H + + CO 2 Glucose Low energy bonds in CO 2 High energy bonds in glucose
Fact Check – Light Independent Reaction 1. In which part of the chloroplast does the light independent reaction occur? 2. What is another name for the Light Independent Reaction? 3. Why is it called the Light Independent Reaction? 4. Which molecule is added to H + (from the light dependent reaction) to make glucose? 5. How does the molecule referred to in #4 enter the chloroplast? 6. 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 CO 2 stomata ATP
Energy Molecules ADP charged up by light energy to produce ATP NADP + charged up by light energy to produce NADPH
Factors affecting Photosynthesis Light - Absence of light no photosynthesis
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
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 CO 2 to be a problem for plant growth on earth? Why or why not?
Environmental Factors Affecting Photosynthesis Complete worksheet “Energy in a Cell”: Critical Thinking and Problem Solving