Lecture 8 - Phototrophy

Question 1

What is phototrophy? Give example of microorganisms

Answer 1

Phototrophy is the utilisation of light to create chemical energy. Microorganism that use light are known as phototrophs. Energy can be harvested from light via redox reactions generating chemical energy. Cyanobacteria and Green algae are two examples

Question 2

Explain the difference between oxygenic and anoxygenic photosynthesis

Answer 2

Oxygenic photosynthesis is photosynthesis that uses water as electron donor resulting in the release of O2. It also involve two photosystems. Where PSII absorbs light and splits water the electron is passed down the electron transport chain to generate ATP. Anoxygenic photosynthesis does not used water as electron donor but H2S or S instead resulting in more oxidised sulfur compounds. Hence, they do not generate O2 and are well adapted to low light levels found down the WGC.

Question 3

What are photoheterotrophs give an example

Answer 3

Use light energy source, can not use CO2 as carbon source, i.e purple sulfur bacteria

Question 4

What are stromatolites?

Answer 4

Its layered structure formed in shallow water by trapping, binding and cementation of sedimentary grains by biofilm of microorganisms, especially cyanobacteria.