Life on Earth

Life on earth

A. Procaryotic Organisms

1. The prokaryotic cell, unlike the eukaryotic cell, is able to survive in an oxygen-deprived, mineral-deprived and vitamin-deprived environment. The normal cells in our body, the eukaryotic cells need oxygen, vitamins and minerals to be able to survive.

2.

The classification system of prokaryotes

Classification of Prokaryotes

Procaryotes can be divided into two distinct groups, archaea and eubacteria. Each group has its own characteristics.

The characteristics of the archaea group is

o No Murein in the cell wall

o The lipids within its cell membrane are branched

o Its RNA synthesis involves one large enzyme

o It is sensitive to the antibiotics streptomycin and chloramphenicol

The Archaea division can be further classified into the three groups: methanogens, halophiles and thermophiles.

The characteristics of the eubacteria group is

o The Cell wall is composed of murein

o The lipids in the cell membrane are not branched

o Its RNA synthesis involves one small enzyme

o It is not sensitive to the antibiotics streptomycin and chloramphenicol

Eubacteria can be classified into a number of different groups, including green bacteria, purple bacteria, spirochaetes, Gram-positive bacteria and cyanobacteria

How technological advances impacted on classifying Procaryotes

Technological advances in the development of microscopy, particularly the development of the electron microscope, have increased our knowledge of procaryotic organisms.

3.

Cyanobacteria

The environment it occupies

Cyanobacteria live in environments that are naturally wet or damp. These environments include: ponds, streams, wet rocks and damp soil. They thrive in warm conditions, especially in areas where the water contains dissolved organic material. They flourish in water that is salty, brackish or fresh, in cold and hot springs, and in environments where no other microalgae can exist.

Cyanobacteria, are small in size. Many form individual filaments, while others form slimy masses. Some cyanobacteria that live in bodies of water, have the ability to produce toxic chemicals, and can reproduce very rapidly, causing a vast, slimy mat (a �bloom’) to form. This bloom poisons the water in stagnant bodies of water such as lakes and slow-flowing streams.

Most marine forms grow along the shore as benthic vegetation in the zone between the high and low tide marks.

Cyanobacteria have an impressive ability to colonise infertile substrates such as volcanic ash, desert sand and rocks. Another remarkable feature is their ability to survive extremely high and low temperatures.

The role it plays in its environment

Cyanobacteria can inhabit many different types of environments. They are photosynthetic organisms, meaning they have the ability to convert light energy to chemical energy as nutrients. They are primary producers at the base of the food chain within their ecosystem.

Cyanobacteria that live in the oceans generate large quantities of oxygen. Stromatolites are cyanobacteria first discovered in fossils more than 3000 million years old. Their abundance and carbonfixation ability in photosynthesis over millions of years contributed to the reduction in carbon dioxide and increase in free oxygen in the Earth’s atmosphere.

Evolution of Australian Biota

B. Adaptations by Australian Plants and Animals

4. The impact on Australian biota of the contraction of rainforests and the spread of sclerophyll communities and grasslands over time.

The contraction of rainforests has several effects on the biota of Australia. Rainforests are the habitat of many Australian plants and animals. With reduced space to survive and