Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
DO NOW: Answer the following question: A plant was planted six months ago that weighed 12 oz (including the soil) in the window. Now the plant and soil weigh 22 oz!!! How is this possible? (No soil was added, and wet soil does not account for the answer). Plants and Light How do plants get their energy? Photosynthesis!!! which means? Using light to make energy. Photo= light Synthesis= to make 2 Types of organisms… Autotrophs make their own food Heterotrophs must obtain food from environment (eat) What are plants? Autotrophs!!! 2 Types of Autotrophs… 1)Photoautotrophs- organisms that use light to make food plants bacteria 2)Chemoautotrophs- organisms that use chemicals to make food. Photosynthesis in brief… Plants are autotrophs, relying on photosynthesis to make food (glucose). What’s required for photosynthesis? Light, CO2, and water… …sugar and oxygen are given off Light Energy!!! Light is a form of radiation, which travels in what are called waves… Let’s see some examples… wavelength Smaller wavelength, but greater frequency… So… Sunlight is a mixture of all visible wavelengths…what color is it? White!!! White light can be broken down into different colors using a prism, which diffracts the light to form a spectrum. Spectrum? A spectrum is simply a distribution of light, arranged in order according to its energy… Good Ole Roy!!! How can you remember the colors? Listed backwards, they spell: ROY G. BIV Why are they arranged this way? It’s due to wavelength… 380 430 500 560 600 750 Why do we see colors? When we see color, it is due to reflected light. This dot, absorbs all light, but that in the red end of the spectrum. Umm Hmm… Substances that absorb light are called pigments. Umm, what doesn’t absorb light? Anything that’s white!!! Photosynthetic Pigments By far, the most important pigment in plants, is chlorophyll. All plants have 2 types of chlorophyll: chlorophyll a and chlorophyll b green Other Pigments Besides chlorophyll, plants have other pigments: carotene (orange) and xanthophyll (yellow) Pigments continued… Why don’t we see the other pigments? They’re masked by chlorophyll, which is present in great quantities. Why are the other pigments there? They absorb light at different wavelengths than chlorophyll. Light Reflected Light Chloroplast Absorbed light Granum Transmitted light Figure 10.7 Photosynthesis again… Where does photosynthesis occur? Plants!!! More specifically? Chloroplasts!!! Anatomy of a Chloroplast: Chloroplasts contain flattened sacs of photosynthetic membranes called thylakoids. A bunch of thylakoids make up grana. The fluid surrounding the grana is called stroma. Why are chloroplasts necessary? Chlorophyll is contained within the grana… Chlorophyll can absorb energy without stroma present, but it immediately gives off the energy as heat or light. Necessity of chloroplasts continued. For chlorophyll to produce food for the plant, all of the enzymes contained within the stroma are necessary. thylakoid stroma grana Photosynthesis Overall reaction 6CO2 + 12H2O Light C6H12O6 + 6O2 + 6H2O Takes place over many steps… Photosynthesis Dissected: Divided into 2 types of reactions: 1)Light-dependent reactions 2)Light-independent reactions Light-dependent reactions Requires light Take place in the grana of chloroplast Store energy in high energy molecules – ATP – NADPH Light Dependent Reactions Chlorophyll a and b absorb blue-violet and red-orange light from sun and excite electrons Transfer excited electrons to NADP (carrier) and convert ADP to ATP Some electrons split water called photolysis Oxygen is released NADP+ + H+ + 2e- ADP ATP 2ephotosystem I 2ephotosystem II 2eH2O 2H+ + ½ O2 NADPH e– Excited state Heat Photon (fluorescence) Photon Figure 10.11 A Chlorophyll molecule Ground state gure 10.14 e– ATP e– e– NADPH e– e– e– Mill makes ATP e– Photosystem II Photosystem I Light-independent Reactions Energy from the light dependent reactions is used to power the light-independent reactions. Do not necessarily occur in the dark, but they don’t require light. Light-independent continued… Occur in the stroma of the chloroplast Series of enzyme controlled steps to convert CO2 and H into glucose. The reaction: CO2 goes through a process known as carbon fixation. CO2 reacts with a 5 carbon sugar called ribulose bisphosphate (RuBP), and then enters the Calvin Cycle Light Independent Reactions H from NAPH2 from light reactions Carbon dioxide from environment Require products from light reactions so stop shortly after light reactions end Water is also a by-product Light reaction Calvin cycle H2O CO2 Light NADP+ ADP +P1 RuBP 3-Phosphoglycerate Photosystem II Electron transport chain Photosystem I ATP NADPH Figure 10.21 G3P Starch (storage) Amino acids Fatty acids Chloroplast O2 Light reactions: • Are carried out by molecules in the thylakoid membranes • Convert light energy to the chemical energy of ATP and NADPH • Split H2O and release O2 to the atmosphere Sucrose (export) Calvin cycle reactions: • Take place in the stroma • Use ATP and NADPH to convert CO2 to the sugar G3P • Return ADP, inorganic phosphate, and NADP+ to the light reactions Factors influencing photosynthesis: There are 3 main factors influencing the rate: 1)Light intensity 2)Temperature 3)Water and mineral availability 4)Carbon dioxide level Photosynthesis vs Cellular Respiration In brief, they are exact opposites: photosynthesis stores energy in glucose, respiration releases energy. Photosynthesis vs Cellular Respiration Photosynthesis: 6CO2 + 12H2O Light C6H12O6 + 6O2 + 6H2O Photosynthesis vs Cellular Respiration Photosynthesis: 6CO2 + 12H2O Light C6H12O6 + 6O2 + 6H2O Respiration: C6H12O6 + 6O2 + 6H2O 6CO2 + 12H2O Leaf cross section Vein Mesophyll Stomata Figure 10.3 CO2 O2