Ch 26: The Origin & Diversity of Life

Question 0

Ribosome activity

Answer 0

- RNA may have been first 
  genetic material
- Amino acids polymerized
  into proteins
- Metabolic paths emerged
- lipid bubbles could inc. 
  chance of metabolic
  reactions 
     - leads to cell
       membranes

Question 1

Plate Tectonics

Answer 1

Continents moved over geological time.

Earth’s crust formed rigid slabs of rock (plates) under continents and oceans

Question 2

Microfossils

Answer 2

• Fossilized forms of micro life
• Oldest: 3.5 billion years ago
• Resemble present-day
  prokaryotes

Question 3

Endomembrane system

Answer 3

Nuclear membrane, only found in eukaryotes, accounts for increased complexity
Golgi apparatus and endoplasmic reticulum facilitate intracellular transport

Question 4

Endosymbiosis

Answer 4

Cells "eat" other cells and 
become multicellular
      -how mitochondria and 
       chloroplasts entered euk
       cells

Question 5

Mitochondria & Chloroplast evolution

Answer 5

Mitochondria:
descendants of relatives of purple sulfur bacteria and the parasite rickettsia.

Chloroplasts:
derived from cyanobacteria

Question 6

Multi-cellularity

Answer 6

• Allowed organisms to deal with environment in many ways
• Allows for differentiation of cells into tissues
• Evolved independently in eukaryotes supergroups

Question 7

Sexual reproduction

Answer 7

-Allows greater genetic diversity
-meiosis
-crossing over
-First eukaryotes probably haploid
-diploid arose independently on
sep occasions (fusion of haploid
cells)

Question 8

Cambrian explosion

Answer 8

• Evo innovations occurred when life primarily aquatic

- 1st multicell animals appeared 50 mil years ago following explosion

Question 9

Moving onto land

Answer 9

• Plants, then animals, colonized terrestrial environments after Cambrian radiation
• plants photosynthesis created o2 in ozone layer

Question 10

Compartmentalization

Answer 10

- Allows increased subcellular 
  specialization
- Nuclear membrane allows for 
   additional levels of control of 
   transcription/translation

Question 11

Hadean Era

Answer 11

Formation of Earth
4.5 BYA
Earth cools around 4 BYA

Question 12

Archean Era

Answer 12

Life emerged (prokaryotes)
Formation of Rodinia
3.5–2.5 BYA

Question 13

Proterozoic Era

Answer 13

Eukaryotes
First multicellular organisms
Appearance of animals and plants
Cyanobacteria
Appearance of oxygen in the atmosphere

Question 14

Fossilization

Answer 14

• Organisms buried in sediment
• Calcium in bone shell or other
  hard tissue mineralizes
• Surrounding sediment hardens
  to form rock
• Erosion must expose fossils

Question 15

Aging fossils

Answer 15

Relative age:
position of the fossil in the sediment

Absolute age: 
age of fossils is estimated by rates of radioactive decay
      -Isotopes transform at
        precise known rates into    
        non-radioactive forms
        (rate of decay = Half life)

Question 16

Miller and Urey

Answer 16

Exper. recreated early atmos.

Assembly:
Reducing atm mix of gases, H with no O gas, placed over water, temp below 100°C

Results:
simulated lightning sparks, & small organic molecules inc. amino acids