Chapter 26 Reading Quiz According to your book, how long ago did life probably originate on Earth?...

Chapter 26 Reading Quiz

1. According to your book, how long ago did life probably originate on Earth?

2. What were probably the first types of life?

3. What was probably the first genetic material?

4. Why do I keep phrasing the questions using “probably”?

5. List the three Domains.

1. Provide at least two lines of evidence for the antiquity of life.

1. The fossil record- although there is no fossil record for the very beginning- stromatolites banded domes of sediment similar to the layered mats constructed by colonies of cyanobacteria and bacteria

2. Contemporary organisms- in their molecules and anatomy they can carry traces of evolutionary history

2. Describe the contributions that Oparin, Haldane, Miller, and Urey made towards developing a model for abiotic synthesis of organic molecules.

Oparin & Haldane postulated that the reducing atmosphere and greater UV radiation on primitive earth favored reactions that built complex organic molecules from simple monomers as building blocksMiller & Urey tested O & H’s hypothesis by simulating the conditions on early earth by constructing an apparatus containing H2O, H2, CH4, and NH3 (stimulated by “lightning”) - produced some amino acids and other organic molecules

3. Provide plausible evidence to support the hypothesis that chemical evolution resulting in life’s origin occurred in four stages:a. abiotic synthesis of organic monomersb. abiotic synthesis of polymersc. formation of protobiontsd. origin of genetic information

1. Laboratory simulations have produced organic polymers- had to happen without enzymes- clay may have been the substrate for abiotic synthesis as monomers bind to charged sites, concentrating amino acids- metal ions could catalyze the dehydration reactions to bring monomers together

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2. Protobionts aggregates of abiotically produced molecules able to maintain an internal environment different from their surroundings and exhibiting some life (metabolism & excitability)- spontaneous formation of protobionts:when mixed with cool water, proteinoids self-assemble into microspheres surrounded by a selectively permeable membrane continued……

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3. RNA was probably the first genetic material- a primitive mechanism for aligning amino acids along RNA molecules were probably the first genes- evidence: RNA molecules may have been able to self-replicate- RNA is autocatalytic (as indicated by “ribozymes”)

4. Describe the basis for Whittaker’s five-kingdom system.

The 2 – kingdom system (plants & animals) was no longer suitable as biologists learned more about the structures and life histories of different organisms1. Monera2. Protista3. Plantae4. Fungi5. Animalia

5. Describe three alternatives to the five-kingdom system and explain the rationale for each.

1. Six – kingdom- prokaryotes are split

based on molecular evidence from an early evolutionary divergence

1. Archaebacteria2. Eubacteria3. Protista4. Fungi5. Plantae6. Animalia

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2. Three – domain- more significance is

given to the split between eu- & archae- bacteria by using the superkingdom taxon “domain”

- Eukarya includes the four kingdoms of the eukaryotes

1. Bacteria2. Archaea3. Eukarya

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3. Eight kingdom- separates the

prokaryotes and the types of protists

1. Bacteria2. Archaea3. Archaezoa4. Chromista5. Protista6. Fungi7. Plantae8. Animalia the

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