Photosynthesis

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Cells Using Biochemical Energy

Cells Use ATP For:

Active transport

Movement

Photosynthesis

Protein Synthesis

Cellular respiration

All other cellular reactions

Slide 14

More on ATP

Cells Have Enough ATP To Last For A Few Seconds

ATP must constantly be made

ATP Transfers Energy Very Well

ATP Is NOT Good At Energy Storage

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Glucose

Glucose is a monosaccharide

C6H12O6

One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP

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History of Photosynthesis & Plant Pigments

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Photosynthesis

Involves the Use Of light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches

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Investigating Photosynthesis

Many Scientists Have Contributed To Understanding Photosynthesis

Early Research Focused On The Overall Process

Later Researchers Investigated The Detailed Chemical Pathways

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Early Questions on Plants

Several Centuries Ago, The Question Was: Does the increase in mass of a plant come from the air? The soil? The Water?

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Van Helmont’s Experiment 1643

Planted a seed into A pre-measured amount of soil and watered for 5 years

Weighed Plant & Soil. Plant Was 75 kg, Soil The Same.

Concluded Mass Came From Water

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Priestley’s Experiment 1771

Burned Candle In Bell Jar Until It Went Out.

Placed Sprig Of Mint In Bell Jar For A Few Days.

Candle Could Be Relit And Burn.

Concluded Plants Released Substance (O2) Necessary For burning.

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Ingenhousz’s Experiment 1779

Repeated Priestly experiment with & without sunlight

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Results of Ingenhousz’s Experiment

Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight.

Light Was Necessary For Plants To Produce The “Burning Gas” or oxygen