Topic 2 - Earth's History

Question 1

What are the three main domains of the Tree of Life?

& what is it based off of?

Answer 1

• Eukarya, Bacteria, Archaea

- mostly from highly conserved DNA sequences (genes encoding ribosomal RNA)

Question 2

What are the 2 defining features of life? (biologists view)

Answer 2

1. Ability to capture energy

2. Ability to use that energy to replicate (make copies) - ability to evolve

Question 3

What were the 2 earliest milestones critical for the emergence of life?

Answer 3

1. the first organic molecules (sugars, amino acids, purines, pyrimidines)
2. first self-replicating polymers (RNA - ability to self-replicate and catalyze)
   - the RNA world

Question 4

History of Earth and the Fossil Record

1. When did the universe emerge?

Answer 4

14 billion years ago

Question 5

History of Earth and the Fossil Record

2. When did the solar system emerge?

Answer 5

4.6 billion years ago

Question 6

History of Earth and the Fossil Record

3. When was the first evidence of cellular life?

Answer 6

3.7 billion years ago

Question 7

History of Earth and the Fossil Record

4. When was the first evidence of multicellular life?

Answer 7

640 million years ago

Question 8

History of Earth and the Fossil Record

- What is the general order of earth’s history and the fossil record?

Answer 8

14 bill – 4.6 bill – 3.7 bill – 640 mill

Universe - solar system - cellular life - multicellular life

Question 9

What where the 4 major events for early evolution?

Answer 9

1. Genetic Code
2. Cells
3. 2 Important Biochemical Pathways
4. Linear Chromosomes

Question 10

What was the importance behind the evolution of the genetic code?

Answer 10

• nearly universal
• provided a link between nucleic acids and proteins

allows for early catalytic capability of building blocks and link to a LUCA

Question 11

What advantages did the formation of cells bring? (2)

Answer 11

• formation of membranes (self-assembling lipid bilayers)
• compartmentalization (reactions could not occur in open environments)
  1. concentrate all reactants & catalysts to increase reaction rates
  2. increased reaction surface area
  3. protect reaction from competition

Question 12

What were the two early biochemical pathways?

Answer 12

• Autotrophic (CO2 fixing) allowing photosynthesis

- Aerobic respiration pathways (increased atmospheric O2 levels)

Question 13

What were some advantages to these two early biochemical pathways?

Answer 13

• using elements around them to synthesize molecules of life
• switch from heterotrophic to autotrophic organisms leading to more complex carbon compounds
• a by product of photosynthesis

Question 14

What did linear chromosomes allow evolution to progress?

Answer 14

• bacterial chromosomes only have 1 OoR meaning replication was slow and limited in size
• compared to a linear chromosome allowing multiple OoR (rapid) and an increase in size of chromosome to carry more information

Question 15

What are 3 distinguishing features of Eukarya?

Answer 15

1. cytoskeleton
2. 1 of several linear chromosomes
3. membrane-bound organelles

Question 16

What was the origin of organelles?

Answer 16

Mitochondria and Chloroplasts descended from bacteria via Endosymbiosis
- engulfed smaller organisms and prevented them from collapsing establishing a symbiotic relationship with them

Question 17

How can we establish the endosymbiotic relationship?

Answer 17

• through the ancestral and symbiont and tracking the movement of chromosomes between them
• certain algae lack the photosynthetic capability and engulf a symbiont with this ability

Question 18

Are Eukarya a monophyletic group?

Answer 18

• there may have been several independent origins of eukaryotic-like cells
• evidence indicate eukarya evolved from a single common ancestor

Question 19

What 2 points were essential attributes necessary for the multicellularity of cells?

Answer 19

1. gene regulation (cell differentiation) - since different cells now have different functions
2. Cell-cell communication (about cell positioning and state of differentiation) - chemical signalling

Question 20

What is an important note about cancer?

Answer 20

• cancer can only evolve in cells with gene regulation

Question 21

What was the first milestone in the evolution of complex life?

Answer 21

Separating genes (forming membranes) – lead to compartmentalization – lead to larger more complex genomes

Question 22

What was the second milestone in the evolution of complex life?

Answer 22

Separate unicells to symbiotic unicells – eukaryotic cells – formation of symbiotic organelle and the transfer of genes between them

Question 23

What was the third milestone in the evolution of complex life?

Answer 23

formation of multicellular organisms – evolution of a cell, tissue differentiation, and somatic/germ cells

Question 24

What does the fossil record include? and how accurate is it?

Answer 24

• fossils only occur in sedimentary rock
• probability of fossilization depends on species and habitat
• fossil must occur near exposed or near-exposed strata
• estimate <1% of once living species are known as fossils
• they indicate life @ that time NOT a time period

Question 25

What is radiometric dating?

Answer 25

- measures the decay of certain radioactive elements in minerals that form in igneous rock

Question 26

What are examples of radioisotopes?

Answer 26

1. U235 -- Pb207 (700 mill) 2. K40 -- Ar40 (1.3 bill) 3. C14 -- N14 ( 5700 years)

Question 27

What is one catch between igneous and sedimentary rock?

Answer 27

Fossils only form in sedimentary rock, however radiometric dating is an estimate using that rock type - thus the best radiometric dating is done using sedimentary rock wedged between two layers of igneous rock

Question 28

When was the Archaean Era?

Answer 28

2.5 billion years ago

Question 29

What originated from the Archaean Era, changed and allowed life to take off?

Answer 29

- it is the origin of cellular life - lead to the diversification of archaea and bacteria - two biological pathways evolved: photosynthesis and autotrophic pathways and aerobic respiration

Question 30

When was the Proterozoic Era?

Answer 30

2.5 billion years ago till about 542 million years ago

Question 31

What was the significant evolution accompanying the Proterozoic Era?

Answer 31

- origin of eukaryotes - origin of multicellular organisms - the oldest fossil around 640 million years ago - but there was little detail to determine structures but we did see a burst of life

Question 32

What time period does the Paleozoic Era encompass?

Answer 32

between 542-251 million years ago

Question 33

Name the 6 Periods encompassed in the Paleozoic Era in order to the most recent

Answer 33

``` COS-DC-P Cambrian Ordovician Silurian Devonian Carboniferous Permian ```

Question 34

Name the key traits of the Cambrian Period?

Answer 34

- introduced many phyla (especially marine), including algae and JAWLESS vertebrates

Question 35

Name the key traits of the Ordovician and Silurian Periods?

Answer 35

- diversification of animal groups, earliest land plants emerged, and JAWED fishes

Question 36

Name the key traits of the Devonian Periods?

Answer 36

- BONY fishes - invertebrates (trilobites, ammonoids) - insects - seed plants

Question 37

What are the key traits from the Carboniferous Period?

Answer 37

- abundant land plants (mosses and liverworts, early vascular plants, seed plants) - winged insects amphibians and reptilians - this formed the present day coal beds used

Question 38

What are the key traits of the Permian Period?

Answer 38

- diversification of fishes, insects and other animals groups - earliest form of mammal-like vertebrates

Question 39

What is a challenge faced by the early plants?

Answer 39

- to avoid desiccation | - to have structural support

Question 40

What are the remaining 2 Eras and there periods in order to the most present?

Answer 40

Mesozoic (250-65 million years ago) - Triassic, Jurassic, Cretaceous Cenozoic (65 million to present) - Tertiary, Quarternary

Question 41

What is one defining feature of the Mesozoic Era?

Answer 41

- it is well inhabited by plants and animals

Question 42

What are the key points from the Triassic Period?

Answer 42

- seed plant domination on land - first dinosaurs emerged - first mammals appeared

Question 43

What are the key points from the Jurassic Period?

Answer 43

- "Marine Revolution" - radiation of dinosaurs - first birds and flowering plants

Question 44

What are the key points from the Cretaceous Period?

Answer 44

- radiation of mammals, birds, and flowering plants | - coincidentally

Question 45

Birds vs their Ancestors

Answer 45

- birds are theropod dinosaurs/ transition from feathered dinosaur to birds - increased brain size?

Question 46

Two groups from which all dinosaurs evolved from?

Answer 46

1. Ornithischia | 2. Saurischia

Question 47

What are the seven differences of birds compared to their ancestors?

Answer 47

- no teeth - larger brain with fused skull bones - reduction of digits of the forelimb - fusion of pelvic bones - fewer tail vertebrae - enlarged, keeled sternum - reinforcing processes on the ribs

Question 48

Who where the ancestors to the birds?

Answer 48

Saurischian theropod dinosaurs

Question 49

What were the other 3 differences between mammals and their synapsid vertebrate ancestors and their ancestors?

Answer 49

- hair: allowed thermal regulation | - mammary glands and changes in diet and their masculature

Question 50

How many years before present did the tertiary and quaternary periods occur?

Answer 50

- Tertiary: 65 million to 5.3 million | - Quaternary: 2.56 million years till present

Question 51

What were the defining features of the tertiary period of the Cenozoic Era?

Answer 51

- cooling climate - radiation of modern groups (mammals, birds, snakes, teleost fishes, flowering plants) - diversification of pollinating insects

Question 52

What are the defining features of the quaternary period of the Cenozoic Era?

Answer 52

- consists of the Pleistocene-Holocene Periods - glaciation and lowered sea levels - extinctions occurring - and the rise of hominins

Question 53

What are 2 significant points that dictated what the Cenozoic Era appeared like?

Answer 53

- groups were recognizable at the beginning of this period | - there was enough variation in the landscape that continental localization affected the climate

Question 54

Evolution of Primates (and Humans) | What was the order of evolution to humans?

Answer 54

``` First primates First monkeys First apes First hominins Earliest Homo H. erectus Modern H. sapiens ```

Question 55

What is the timeline for the first primates?

Answer 55

- primates during the early Cenozoic Era (Paleocene) - moneys during the Oligocene period - apes during the miocene period around 22 million years ago

Question 56

What was the first timeline of the first hominins?

Answer 56

Sahelanthropus - late Miocene 6 million years ago | Australopithecus - later on 3.5 million years ago

Question 57

What was the first timeline of the first Homo species?

Answer 57

- earliest Homo during the late Piocene and early Pleistocene around 1.9 million years ago - H. erectus was around 1.6 million years to 200,000 years ago - H. sapiens was around 170,000 years ago

Question 58

Name the order of evolution from chimpanzees to homo sapiens.

Answer 58

``` Chimpanzee Australopithecus afarensis Australopithecus africanus Homo habilis Homo erectus Homo neaderthalensis Homo sapiens ```

Question 59

Name the 5 Eras in order from oldest to present day, including their important Periods.

Answer 59

APP-MC - Archaean - Proterozoic - Paleozoic: Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian - Mesozoic: Triassic, Jurrassic, Cretaceous - Cenzoic: Tertiary and Quaternary