Lecture 21

Question 1

Which evolved first, bacteria and cyanobacteria, or the apex chert?

Answer 1

Bacteria and Cyanobacteria.

Question 2

What are Cryptozoon?

Answer 2

The hiddn animal. Rocks that are older than Cambrian Rocks.

Question 3

Where did we find Cryptozoon?

Answer 3

Schreiber Beach

Question 4

What did we discover on Schreiber beach?

Answer 4

Observed column like structures and layering that demonstrates the structures ability to grow. Also observed fossilized bacteria like organisms.

Question 5

What did the discoveries on Schreiber beach indicate?

Answer 5

That the first organisms were older than the phanerozoic, Proterozoic boundary (bacteria and cyanobacteria)

Question 6

What did we discover in Shark Bay?

Answer 6

Column like formations existing in the zone between the lowest and highest tide. Support high water energy. Found more cryptozoon.

Question 7

What are stromatolites?

Answer 7

Column like structures (cryptozoon is one of them). Successions of accumulations of limestone. Presents different shapes Distribution and morphology is affected by water depth and energy. Not an organism, but a structure that houses billions of prokaryotes.

Question 8

Where were the oldest stromatolites?

Answer 8

Fig tree Formation in South Africa-3.2 billion years old.

Question 9

What are the four components of stromatolites?

Answer 9

Growth surface, Undermat, Oxygen-depleted Zone, Stromatolite Mass

Question 10

What is the Growth surface?

Answer 10

Thin layer (1mm) consisting of oxygen-producing photosynthetic cyanobacteria and aerobic bacteria.

Question 11

What is the Undermat?

Answer 11

Thin bacterial layer (1mm), consisting of non-oxygen producing photosynthetic bacteria and anaerobic bacteria that can use oxygen.

Question 12

What is the Oxygen-depleted zone?

Answer 12

Thick layer (around 1-2 centimetres). Only anaerobic bacteria (extremophiles).

Question 13

What is the Stromatolite mass?

Answer 13

Includes most of stromatolite (a few centimeters to 1 metre). Non-living rock. Consists of calcium carbonate.

Question 14

When did the stromatolites first start appearing?

Answer 14

In the Mesoarchean. Anything older is uncertain.

Question 15

When did stromatolites reach global distribution?

Answer 15

In the Neoarchean (where there was water)

Question 16

What major event in the history of life happened in the Paleoproterozoic?

Answer 16

Gun Flint Formation- stromatolites produced and expelled mass amounts of oxygen.

Question 17

When did Earth’s atmosphere change from reducing to oxidizing?

Answer 17

In the Archean Proterozoic boundary.

Question 18

What happened in the Phanerozoic?

Answer 18

Earliest gastropode organisms evolved. Fed on stromatolites. Reduced stromatolites back to patchy distribution.

Question 19

What happened when the atmosphere changed from reducing to oxidizing?

Answer 19

Became toxic for Archean organisms. First mass extinction. Some prokaryotes lived due to symbiosis.

Question 20

What are Eukaryotes?

Answer 20

Organisms with a true nucleus in cytoplasm mass. Larger than prokaryotes. Also have organelles.

Question 21

What was the most important event in the emergence of life?

Answer 21

When prokaryotes turned into eukaryotes?

Question 22

What was discovered about Eukaryotes that suggest how they formed?

Answer 22

Organelles have the same chemical composition as bacteria and cyanobacteria. Different prokaryotes clustered to form a eukaryote that was more adapted for the oxidizing atmosphere.

Question 23

How did Eukaryotes begin the process of evolution?

Answer 23

Reproducing sexually. Producing distinct egg cells with mutations. Evolution itself evolved.

Question 24

What is a Bangiomorpha?

Answer 24

Eukaryote with an Algae body. Consists of many cells. Demonstrate that algae developed multicellularity, Primitive and holds fast to sea floor. Erect body rose up to sunlight like other plants and trees in order to get energy.

Question 25

What is Torridonophycus?

Answer 25

Green algal. Has chlorophyte (major oxygen producers). In high stress, protects itself with a bag-like structure called the Architarch. Would leave when there were good conditions. Could live in marine conditions, lakes, and moist soil. Earth began to become green as organisms moved inland.

Question 26

What is melanocryllium?

Answer 26

Organic Eukaryote. testate amoebas that have a similarities with the first organisms which evolved an animal like metabolism. THE EARLIEST ANIMALS.

Question 27

How old are all the Eukaryotes mentioned?

Answer 27

Proterozoic age (11.1-11.5).