The Flow Of Energy Part 3c

The Flow of Energy part 3 Photosynthesis

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• The range of colours which make up white light and are visible to the human eye is called the Visible Spectrum. • Infrared and Ultraviolet would be at either end of the spectrum and are not visible to humans

Photosynthesis • Colour is a property of light that depends on wavelength. When light falls on an object, some of it is absorbed and some is reflected. The apparent color of an opaque object depends on the wavelength of the light that it reflects; e.g., a red object observed in daylight appears red because it reflects only the waves producing red light. The color of a transparent object is determined by the wavelength of the light transmitted by it. An opaque object that reflects all wavelengths appears white; one that absorbs all wavelengths appears black.

Chlorophyll • The intense green colour of chlorophyll is due to its strong absorbencies in the red and blue regions of the spectrum, shown in Because of these absorbencies the light it reflects and transmits appears green.

Cartenoids • Carotenoids: This is a class of accessory pigments that occur in all photosynthetic organisms.. Carotenoids absorb light maximally between 460 nm and 550 nm and appear red, orange, or yellow

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Plants absorb a common gas called carbon dioxide, pull water up through their roots and use light to make sugar. Plants use the sugar to grow. Plants give off oxygen as a by-product. The green parts of the plant makes the sugar and oxygen.  Carbon dioxide + water + sunlight = sugar + oxygen Watch video

The Light Reactions • Photosynthesis is divided into 2 main sets of reactions . • 1. Light Reactions (Occurs in Grana) • The purpose of the light reactions is to change light energy into chemical energy of ATP and NADPH. • Light energy is absorbed and converted to chemical energy • Water is split into H+ ions, oxygen and electrons • H+ from the water are attached to carrier co-enzymes (NADP) for use in photosynthesis (see page 157)

The Calvin Cycle AKA The Dark Reactions • (Occurs in Stroma) • The purpose of the Calvin Cycle is to change CO2 into sugar by adding energy & the H+ from ATP & NADPH. • a) Can occur in light or dark. • b) 6 CO2 & lots of ATP & NADPH are needed to make one sugar molecule. • c) The sugar is then used for plant growth or stored for use in