Chapter 25

Chapter 25 - ii Were possibly undigested prey or internal...

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Chapter 25 I. Concept 25.3: Key events in life’s history include the origins of single celled and multicelled organisms and the colonization of land II. What were the earliest organisms like? a. First organisms were prokaryotes b. Bacteria and archaea c. Fed on accumulated organic molecules (heterotrophic) some were likely autotrophic III. Oxygen a. Oxygenic photosynthetic bacteria evolved between 3.5 and 2.7 BYA b. CO2 + H20 Food + O2 c. Oxygen begins accumulating in the atmosphere 2.7 BYA IV.Which is the correct sequence of events? a. Anaerobic cells > photosynthesis > O2 > aerobic metabolism i. Cannot have oxygen before we have photosynthesis V. The first Eukaryotes a. Oldest fossils of eukaryotic cells are 2.1 BY old b. Endosymbiotic theory i. Mitochondria and plastids were formerly small prokaryotes living within larger host cells
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Unformatted text preview: ii. Were possibly undigested prey or internal parasites or mutualists 1. Instead of eating prokaryote, harbored within the cell and the symbiote got nutrients inside. Then exchanged symbiote ATP and gave leftovers to host. Over time, symbiosis neither could survive without each other. VI.What evidence suggests that eukaryotic cells formed symbiotic relationships with bacteria a. Both chloroplasts and mitochondria contain DNA that is distinct from that found in the nucleus of the eukaryotic cell b. Similarities in inner membrane structure and functions c. Both chloroplasts and mitochondria have their own ribosomes and make proteins independent form the cell d. All of the above VII. Clock Analogy a. 26.10 b. shows time scales involved in the history of life on Earth...
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Chapter 25 - ii Were possibly undigested prey or internal...

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