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66 Cards in this Set
- Front
- Back
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uses light to make food and fuels biosphere |
Photosynthesis |
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capture light energy |
Chloroplasts |
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distance from sun in which light is captured |
150 M km |
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self feeding |
Autotrophs/Photoautotrophs |
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Depend on others to be fed |
Heterotrophs |
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Autotrophs helps us by |
Feeding, clothing, housing, warming, lighting, transporting, and manufacturering |
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Needed by autotrophs to make own food |
light, H2O, CO2 |
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Are chloroplasts only found in leaves |
No. All green parts of plants like stem |
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Where does green color comes from |
Chlorophyll (light absorbing pigment) in chloroplasts |
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Where are chloroplasts concentrated |
mesophyll cells (cross section) |
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CO2 enters and O2 exits in tiny pores called |
Stomata |
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Water absorbed by roots and delivered by veins in |
Leaves |
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1800s reaction of photosynthesis |
light energy + 6CO2 + 6H2O ~ 6Glucose + 6O2 |
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What is reduced |
CO2 to glucose |
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What is oxidized |
Water to Oxygen gas |
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Initial hypothesis |
CO2 splits and O2 released as gas and C binds with water to form sugar |
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Who challenged initial hypothesis and when? |
C.B. Van Niel 1930 |
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What was his work about |
photosynthesizing bacteria that produced sugar without release of O2 |
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What was his hypothesis |
H20 splits O2 release as gas and H incorporated into sugar |
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It was confirmed after and through |
20 years using heavy isotope of oxygen O-18 |
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What further improvements? When and by whom? |
Mid 1940s American biochemist Melvin Calvin. radioactive C-14. trace intermediate molecules formed in cyclic pathway that produces CO - sugar. |
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What type of energy is photosynthesis? |
Endergonic |
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What are two stage of photosynthesis |
light reactions and calvin cycle |
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linked by |
ATP and NADPH |
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Where do both stages occur |
Chloroplasts |
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Where do light reactions occur |
Thylakoids |
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What passes through light reactions |
H20 to O2 |
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Where does Calvin cycle occur |
stroma |
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What goes through Calvin cycle |
CO2 to sugar |
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Does Calvin cyle require light |
No. It's called dark reactions |
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For chloroplasts to produce sugar from CO2 they need |
ATP, NADPH |
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Light reactions summary |
Convert solar energy to chemical energy |
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What drives light reactions |
visible radiation absorbed by pigments |
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Sunlight also called as |
Radiation or electromagnetic energy |
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photons are |
discrete packs of energy |
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Properties of photons |
has fixed quantity of energy, high W, low F, low energy |
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What are pigments and where they are built |
Absorbs, reflects, transmits light at diff wavelengths. Built in thylakoid membranes |
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Chloroplasts contain more than |
one pigment and with diff wavelengths |
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Describe a photosystem. |
Photon of lights hits chloroplast, excited state electron goes up, for back releasing energy and light |
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What are two complexes |
Reaction center and light harvesting |
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Why intact chlorophyll do not release heat and light compared to isolated chlorophyll |
has primary electron acceptor |
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Compare photosystem I from II |
Same until primary electron acceptor accepts. II - electron transport chain I - NADP to NADPH |
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What happens to H+ due to ETC |
pumps into thylakoid space from stroma |
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Where does NADPH and ATP go |
Calvin cycle |
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Calvin cycle |
Reducing CO2 to sugar |
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Carbon fixation |
3CO2 added to 3 5-carbon sugar by rubisco enzyme |
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Product in carbon fixation |
6 3-carbon P |
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Intermediate process |
6 ATP to ADP, 6 NADPH to NADP |
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Reduction |
Produces 6 G3P |
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What happens next |
1 G3P released |
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Then |
5G3P left, 6 ATP to ADP |
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Then, regeneration of RuBP |
From 5G3P to 3 5-carbon P |
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Total |
9 ADP, 6 NADP |
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What happens in photorespiration (C3) |
O2 builds up, rubisco adds O2 to RuBP instead of CO2 |
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Product |
2-C compound |
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Unlike cellular respiration |
uses ATP instead of produce, yields no sugar but CO2 and H2O |
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C4 (sugar cane) |
harvest CO2 even in low amounts, high affinity to CO2 |
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CAM (pineapple) |
fixed 4 C compounds, banks CO2 at night, release at day |
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Why photorespiration occur less in C4 and cam plants compared to the C3 |
theres enough CO2 |
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Global significance of photosynthesis |
provides O2 for all living organisms creates sugar (raw materials, org compounds) |
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increase CO2 results to |
increase plant productivity |
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But there is |
Higher growth in weeds compared to trees and crops |
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FACE exp showed |
149 poison ivy to 15 trees |
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CO2 makes poison more |
potent |
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Greenhouse effect |
greenhouse gases traps heat in atmosphere and radiated back to earth |
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Highest percentage of greenhouse gas |
CO2 methane |
