Life on Earth

Question 1

what are the four main eras of earth’s history

Answer 1

Phanerozoic
Proterozoic
Archean
Hadean

Question 2

Phanerozoic era length

Answer 2

present- 500 MYA

Question 3

Proterozoic era length

Answer 3

500 - 2500 MYA

Question 4

Hadean era length

Answer 4

3800 - 4600 MYA

Question 5

Archean era length

Answer 5

2500 - 3800 MYA

Question 5

explain the Archean era

Answer 5

planet cooled slightly, releasing water vapour from rocks, first life emerged (prokaryotes)

Question 6

explain the Hadean era

Answer 6

volatile earth, comes from hades greek god of hell, lots of toxic gases and acids,

Question 7

how did life begin? (4)

Answer 7

simple organic molecules -> replicating molecules -> natural selection and evolution

Question 8

what role mineral rich oceanic chimneys have in the evolutionary beginnings of earth’s basic life forms

Answer 8

mineral rich chimneys - chemical reactions between hydrogen and carbon dioxide form complex organic compounds

Question 9

key features of prokaryotic organisms ( basic shit ik but u better remember this shit spastic)

Answer 9

prokaryotes evolved from protocells (not a key feature but still important)

single-celled
no nucleus (nucleoid - DNA ring)
no organelles
Thylakoid membranes - photosynthesis

Question 10

what are oldest organisms on earth

Answer 10

stromatolites, hard structures consisting of cyanobacteria bound with sediments,

Question 11

explain the Proterozoic era

Answer 11

eukaryotes came in

Question 12

how did eukaryotes evolve

Answer 12

the theory of endosymbiosis

ancestrial eukaryotic cell + aerobic bacterium = animal cell lineage (wherein the aerobic bacterium became the mitochondria)

ancestrial eukaryotic cell + cyanobacterium = plant cell lineage (where in the cyanobacterium became the chloroplast)

Question 13

why did the evolution of multicellularity occur? (4)

Answer 13

cells evolved aggregation

to avoid predation
functional specialisation
integration of environmental cues

Question 14

explain the Phanerozoic era

Question 15

Cambrian explosion

Answer 15

Trilobites: earliest arthropods (=insects,
arachnids, crustaceans)
20,000 species (most common fossils in
Cambrian rocks)
Evolved exoskeletons within a few million
years
Nutrients from continental erosion
increased food web complexity (predator-
prey arms race)

Question 16

emergence of land plants

Answer 16

Early land plants had rudimentary pores and
lacked roots
Increase in mudrock associated with increase in
early land plants
Land plants released phosphate
Food chains

Question 17

tetrapod evolution

Answer 17

paired fins of fishes have bones that are homologous (similar structures with same evolutionary origin)

Question 18

global distribution of flowering plants

Answer 18

higher diversification rates in dry land areas than in tropics

Question 19

permian-triassic extinction

Question 20

Cretaceous-Tertiary KT (Paleogene) extinction

Answer 20

Massive asteroid hit Yucatan peninsula (Mexico)
75% of al plants and animals lost
Nearlv all dinosaurs and many Invertebrates
became extinct (e
*g., ammonolas
Al tetrapods > 25kg became extinct
Onlv lines of archosaurs to survive became moderr
birds and crocodiles

Question 21

what shapes animal colouration

Answer 21

social environment, ecological interaction, physical environment

these all act as external stimuli

Question 22

what is the point of animal colouration

Answer 22

mate attraction
social signalling
territory defence
camouflage

Question 23

stripes pattern function

Answer 23

breaks up outline of body
distorts animals speed
deter biting flies

Question 24

spots pattern function

Answer 24

draw attacks to less-vital body areas
mimic predator’s eyes