Photosynthesis

Photosynthesis Photo – light Synthesis – making or putting together

Process that converts light energy from the sun into chemical energy (stored in chemical bonds of sugar) and oxygen

Energy for all life on Earth ultimately comes from photosynthesis.

6CO2 + 12H2O + light C6H12O6 + 6O2 +

6H2O Photosynthesis occurs in• land plants,• algae, phytoplankton• cyanobacteria

Photosynthesis reactants

CO2 for photosynthesis is produced by cellular respiration reactions in the mitochondria of all living organisms

H2O for photosynthesis is found in water (for aquatic plants) and in the atmosphere (for land plants)

Light energy

Sun is the primary source of light energy for photosynthesis

Fusion reactions in the sun produce photons that are transferred by radiation to Earth

Chloroplasts

Organelles in algae, phytoplankton, and plant cells where photosynthesis takes place

Complex internal structures

ChlorophyllGreen pigment found in

chloroplasts At least 3 different forms:

chlorophyll a, chlorophyll b, and chlorophyll c.

Other pigments help in a small way in photosynthesis – not green (yellow, red, orange)

Photosynthesis produces oxygen

Photosynthesis produces glucose

Glucose is a simple sugar

Plants convert glucose to other sugars or starches for storage

Plants and animals use glucose in cellular respiration to get energy for cell functions

Electromagnetic WavesLight is an electromagnetic waveA transverse wave that does not

require a medium, therefore it can travel through space

Light can travel through certain media

Visible light is part of a range of electromagnetic waves known as the electromagnetic spectrum

Electromagnetic Spectrum

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12

Pigments

Pigments: molecules that absorb visible light

Each pigment has a characteristic absorption spectrum, the range and efficiency of photons it is capable of absorbing.

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Pigments

chlorophyll a – primary pigment in plants and cyanobacteria

-absorbs violet-blue and red light

chlorophyll b – secondary pigment absorbing light wavelengths that chlorophyll a does not absorb

Factors influencing the rate of photosynthesis

Carbon dioxide concentrationWater availabilityLight intensityWavelength of lightTemperature

Chromatography

Process used to separate different substances based on the different rates of dissolving.

Spinach Chromatography

Different pigments dissolve at different rates

Carotene is at the top, dissolves first

Xanthophyll dissolves next

Chlorophyll aChlorophyll b is last

Phenol Red pH Indicator

A – acid solutionB – basic solutionC – orange – red,

slightly acidic (CO2 present in solution)

D – reddish pink, basic solution Elodea has removed CO2 from the solution

A B C D