Week 5: Emerging Complex Life and Intelligence

Question 1

What is the Proterozoic eon? What changes characterize its start?

Answer 1

2.5 billion - 541 million years ago
where fossil record begins
simple life proliferates + multicellular life emerges
rise of eukaryotic cells + aerobic respiration
begins with huronian glaciation - temperatures decrease and glaciers cover earth’s surface

Question 2

What is the huronian glaciation?

Answer 2

2.4-2.1 billion years ago
first snowball earth
period of low temperatures and glaciers covering earth’s surface

Question 3

What caused the huronian glaciation?

Answer 3

oxygen from photosynthesis dilutes greenhouse gases in atmosphere and decreases the greenhouse effect
feedback loop where snow + ice reflect sunlight and lead to more cooling, which leads to the formation of more snow and ice

Question 4

How does aerobic comparison compare to anaerobic respiration?

Answer 4

requires oxygen
produces 18x more energy!! much more efficient

Question 5

How did the rise of oxygen levels impact organisms using anaerobic respiration?

Answer 5

oxygen has oxidizing and corrosive effects
free oxygen reacts with molecules to produce free radicals, which can cause cell damage

Question 6

True or false: aerobic respiration was first used by prokaryotic cells and allowed eukaryotic cells to develop.

Answer 6

false
eukaryotic cells started it

Question 7

How did eukaryotic cells form in theory?

Answer 7

prokaryotes form symbiotic relationships with each other and eventually one absorbs the other
become chimeric cells
absorbed cells become membrane bound organelles

Question 8

When did eukaryotic cells emerge?

Answer 8

2.1 - 1.6 billion years ago

Question 9

How are eukaryotic cells stronger than prokaryotes?

Answer 9

able to adapt to a wider range of environments due to specialized organelles

Question 10

How did the huronian glaciation period end?

Answer 10

volcanic activity revived greenhouse effect + warmed the planet

Question 11

How did the end of the huronian glaciation period impact life on earth?

Answer 11

prokaryotic and eukaryotic life thrives and diversifies

Question 12

When did multicellular life begin?

Answer 12

2 billion years after huronian glaciation period
575 million years ago

Question 13

When did sexual reproduction emerge? How did it benefit life?

Answer 13

in Proterozoic era
allows mixing of genetic material -> increased genetic diversity
allows complex information to be passed on

Question 14

How does the structure of DNA allow for sexual reproduction?

Answer 14

double helix with rungs made of paired nucleotides
pairs allow for replication

Question 15

What nucleotides bond to which nucleotides?

Answer 15

cytosine bonds to guanine
adenine bonds to thymine

Question 16

What is a genetic code?

Answer 16

sequence of base pairs (DNA)

Question 17

What is a codon?

Answer 17

three base pairs (DNA)

Question 18

What is a gene?

Answer 18

sequence of codons (DNA)

Question 19

What is a genome?

Answer 19

set of genes

Question 20

What is the purpose of genes?

Answer 20

instruct assembly of proteins

Question 21

What is a chromosome?

Answer 21

condensed genome
used for sexual reproduction

Question 22

What is a gamete?

Answer 22

male/female reproductive cell
contain half of their organism’s chromosomes (make up a complete set when combined)

Question 23

True or false: sexual reproduction is less energy intensive than asexual reproduction.

Answer 23

false
it requires a lot more energy

Question 24

What is the Cryogenian glaciation?

Answer 24

720-635 million years ago
2nd snowball earth
glaciers covered earth
emergence of first multicellular organisms during this period

Question 25

what is the cambrian explosion?

Answer 25

20-25 million year period where "burst of evolutionary innovation" occurred

Question 26

What is the phanerozoic eon?

Answer 26

began with cambrian explosion

Question 27

What is a chordate? When did they emerge?

Answer 27

ancestors of vertebrates during cambrian explosion

Question 28

True or false: genetically most organisms are very similar to each other

Answer 28

true sequences of base pairs are different, but at the cellular level they are mostly the same

Question 29

What are hox genes?

Answer 29

code for proteins specific to certain species that regulate genetic expression differentiate different species determine what structures form in a developing embryo

Question 30

what motivated the evolution of hox genes?

Answer 30

mobility is good for survival hox genes allow species to replicate previously evolved body plans instead of coming up with them freshly

Question 31

What is the ordovician period?

Answer 31

488 million years ago plants begin to colonize land

Question 32

What is the carboniferous period?

Answer 32

359-299 million years ago plant growth covers land and becomes modern day coal deposits pangaea forms oxygen levels reach peak concentrations

Question 33

What is a biosignature?

Answer 33

object, substance, or pattern that requires life in order to form

Question 34

Give three examples of potential biosignatures:

Answer 34

temporal variability of atmosphere composition (ex. oxygen) change of planet surface reflectance due to biological life / activity technosignatures indicating intelligent civilization

Question 35

What are the two main aspects of modern evolutionary biology?

Answer 35

studying lines of DNA and fossils

Question 36

What types of mutations are preserved by natural selection?

Answer 36

those that allow organisms to: survive long enough to produce produce offspring that are more likely to survive hunt or scavenge more effectively evade predators more effectively

Question 37

What two main environmental factors drive natural selection?

Answer 37

survival competition for resources

Question 38

How have earth organisms adapted to the energy emitted by the sun?

Answer 38

sight has adapted to the wavelengths which the sun emits the most of (visible light wavelengths)

Question 39

true or false: by looking at the genomes of modern day species, we can accurately estimate a timeline for when species emerged

Answer 39

false timeline part is not accurate

Question 40

What is LUCA?

Answer 40

last common universal ancestor hypothetical organism with first genetic information that eventually led to all other life

Question 41

What three categories make up the tree of life?

Answer 41

bacteria archaea eukarya (includes plants and animals as small branches)

Question 42

What are mass extinction events?

Answer 42

events which apply natural selection forces to the whole planet at once rapid decrease in biodiversity spike in biodiversity caused by end of these events

Question 43

What is the KT extinction?

Answer 43

mass extinction event 66 million years ago caused by asteroid killed of dinosaurs :(

Question 44

how did mammals survive the KT extinction?

Answer 44

burrowing underground to avoid harsh surface conditions omnivorous so they could continue to find food

Question 45

what are primates? When did they emerge?

Answer 45

mammals evolved for life in trees 65.5-55.8 million years ago in early paleocene epoch

Question 46

What is the eocene epoch?

Answer 46

55.8-33.9 million years ago emergence of early placental mammals

Question 47

When did the first human ancestor emerge?

Answer 47

7-5 million years ago

Question 48

True or false: the evolution of bipedalism happened gradually and linearly over time

Answer 48

false it was not linear at all!!

Question 49

When did neanderthal humans exist?

Answer 49

400,000 - 40,000 years ago

Question 50

true or false: neanderthals coexisted with homo sapiens for a time

Answer 50

true for about 5,000 years probably some genetic mixing between the species

Question 51

What is EQ?

Answer 51

encephalization quotient ratio of brain mass to body mass correlatd with intelligence humans have the highest (7.4-7.8)