The main source of energy for MOST ecosystems on Earth is: What is the process that AUTOTROPHS use to capture sunlight energy?

The Nature of Sunlight Sunlight strikes the Earth as a form of electromagnetic energy. Electromagnetic energy takes the form of a wave, with each type having a distinct wavelength. Wavelength: the distance between two adjacent crests in a wave series.

One Wave Length

The Electromagnetic Spectrum The electromagnetic spectrum represents the entire range of wavelengths of energy. 10-5 nanometers (gamma rays) (very short wavelength, high energy) 103 meters (radio waves) (very long wavelength, low energy)

The Segment of Light Important to Life on Earth Visible light has a wavelength range of 380 to 750 nanometers. Other wavelengths have an impact, but are not vital for photosynthesis. Ex: Ultraviolet (UV) rays, Gamma rays, Infrared rays.

The Three Fates of Light Visible light that strikes an object can be: Reflected from the surface or internal structures of the object. 2) Transmitted through the object. 3) Absorbed by the object. The colors that we can see are either reflected light or transmitted light.

The Three Fates of Light

Absorbance of Light Substances that absorb visible light are called pigments. We see green plants because chlorophyll in the plants absorb red and blue wavelengths, while reflecting green wavelengths.

Plant Pigments There are several pigments in plants, but only a few are involved in photosynthesis. The two pigments most involved with the capture of sunlight energy are chlorophyll a and chlorophyll b. Another important type of pigments are the carotenoid pigments.

Pigments involved in photosynthesis are located on the thylakoid membranes of the chloroplasts.

Structure of Chlorophyll Chlorophyll has a large ring assembly with a magnesium atom at its center. A long hydrophobic tail anchors the pigment to the chloroplast.

Chlorophyll Absorption Spectrum Both Cha and Chb absorb wavelengths in the red and blue parts of the spectrum. Carotenoids also absorb in the blue part of the spectrum, and may help absorb excess energy from light in those wavelengths.

The ABSORBTION SPECTRUM of PLANTS

Photosynthesis: How AUTOTROPHS gather energy. Photosynthesis is an ENDOTHERMIC reaction, meaning it TAKES IN energy. Where does it get the energy from? In addition to needing sunlight, plants also need two chemicals for photosynthesis to work: Water, or H2O Carbon Dioxide, or CO2

CO2 + H2O C6H12O6 + O2 H2O and CO2 are called the REACTANTS in Photosynthesis. CO2 + H2O C6H12O6 + O2 C6H12O6 (Glucose) and O2 (Oxygen) are the PRODUCTS of Photosynthesis

What does the plant use the Glucose for? What does the plant use the Oxygen for?

Thomas Engelmann’s Experiment (1883) Illuminated long strands of filamentous algae with different wavelengths, and used aerobic bacteria to show which segments were producing oxygen.