Evolution of eukaryotic cells and atmospheric oxygen during the Precambrian

¶ … evolution of eukaryotic cells linked to the increase of atmospheric oxygen concentration during the Precambrian?

Increase of atmospheric oxygen during the Precambrian period led to creatures which were more dependent on oxygen in the atmosphere. Oxygen levels in the atmosphere increased from 1% to 15% of the modern level of oxygen. The increase in oxygen in the air led to the evolution of more expansive lungs which were capable of taking in more air and converting it into energy. As eukaryotic cells evolved, they became more capable of respiration which added to the complexity of the evolutions of creatures.

Scientists believe that if there are no controls on the emission of CO2 from burning fossil fuels, the concentration of this gas could double by the end of the current century, leading to a significant rise in the average temperature of the Earth. What would be some of the likely evolutionary effects of this climatic change?

Scientists believe that if the carbon dioxide from burning fossil fuels continues to build up in the atmosphere, the repercussion for the environment will be serious. Since average temperatures will increase, animals would have to evolve skin which was less warm such as the eradication of fur. Certain animals, such as lizards and reptiles who already live in high temperature areas would appear in other areas. Also, the creatures would have to adapt to breathe in carbon dioxide in greater amounts which would be difficult.

3. If we were concurrently living during one of the cooler periods in the Earth's history, why should we still be concerned about human activities that are thought to contribute to global warming?

The reasons that people should be concerned about global warming and their contributions to it is that even though we are currently in a cool period, there may be detrimental effects which would bring out a change which could eradicate all mankind. Many things could happen, including changes in weather patterns and extinction of populations which would upset the food chains of areas and may have world-wide effects. Sea levels could raise destroying homes and making land go under sea level putting millions out of their homes or dying from drowning.

4. Construct your own chart in order to summarize the geological and evolutionary events of the major periods that make up the four geologic eras of the Earth's history. Focus on major events only and avoid unnecessary detail.

Era

Events

Phanerozoic (540 million years ago -- today)

Cenozoic: first people, mammoths, & other prehistoric creatures

Mesozoic: dinosaurs

Paleozoic: first plants and life forms

Proterozoic (2.5 billion years ago -- 540 million)

Vendian: sponges and multi-celled organisms

Early Proterozoic: first multi-cellular creatures; oxygen builds up on earth

Archeozoic (3.9 billion -- 2.5 billion years ago)

Little free oxygen; first rocks and oceans formed