PhotosynthesisTopic E: 3.8 & 8.2

What is Photosynthesis?A)The production of carbon

compounds in cells using light energy

B)The opposite of respiration

C) A reaction only carried out by plants

D) The production of light energy by plants cells

Done by plants and some bacteria, and some protists

Photosynthesis The equation is almost the opposite of

respiration 6CO2+ 6H2O + light C6H12O6 + 6O2

Low energy molecules become a high energy molecule

Photosynthesis has 2 stages

Photosynthesis has 2 stages: 1) Light-dependent reactions:

Require continual supply of light produce compounds used in…

2) Light-independent reactions: Can run in darkness until above compounds are

used up. Produce glucose, amino acids and other organics.

So the process requires light…

But not all light is equal

Light

Spectrum: range of wavelengths of radiation. Short = blue; medium = green/yellow; long =

orange/red. The efficiency of photosynthesis depends on the

wavelength. Action Spectrum: the percent of light of a

wavelength that is used in photosynthesis.

Action Spectrum of Photosynthesis

The shorter and longer wavelengths are used most efficiently.

These colours are red and blue light Explained by different photosynthetic pigments. Main pigments are chlorophyll a & b Compare Action Spectrum to

Absorption Spectrum Very similar to action spectrum. Absorption Spectrum: the percent of light

of a wavelength that is absorbed by the pigments.

If light is not absorbed it is reflected or transmitted.

Chlorophyll absorbs red and blue light most effectively and reflects green light more than other colours

Why leaves appear green.