Life on Earth Flashcards
(37 cards)
1
Q
all living things:
A
respire, reproduce, respond, excrete waste, move
2
Q
first living thing on earth
A
LUCA:
- last
- universal
- common
- ancestor
3
Q
evidence of early earth:
A
- lacked nitrogen, oxygen and carbon dioxide
- abundance of methane, ammonia, water vapour, and hydrogen gas
4
Q
theory: outer space
A
- rocks from meteorites, comets, and Mars have been studied, 74 amino acids found on a meteorite
- 75% of molecules tested from space are organic
- evidence supports theories that organic molecules evolving on primitive earth was aided by molecules from comets and meteorites
5
Q
theory: Haldane and Oparin
A
- believed life have evolved from conditions of early earth
- found the basic chemical building blocks of life: amino acids chemically evolved from lightning, heat (volcanoes) and ultra violet light
6
Q
chemical origins of light beyond earth
A
- suggested that comets, interplanetary dust particles and meteors brought gases and water into earth’s atmosphere
- comets made of ice and dust, as it passes through warm solar system, boiled away and gases and dust attracted to atmosphere by gravity
7
Q
panspermia:
A
- where life is distributed by comets/asteroids to planets
8
Q
Urey and Miller:
A
- experiment to test Haldane and Oparin theory: how did the origin of life on earth begin, from its own organic chemicals on earth
- in 1953, Stanley Miller in Harold Urey’s lab sent electrical currents through a chamber of methane, ammonia, hydrogen and water
- imitated the primitive earth conditions
- able to yield organic compounds including amino acids: building blocks of life
- demonstrated that complex organic molecules could be produced naturally
9
Q
Technological advancements:
A
- radiometric dating
- electron microscope
- biochemical analysis and DNA technology
- deep ocean technology
10
Q
radiometric dating:
A
- different number of neutrons: called ‘isotopes’
- some isotopes can be radioactive
- allowed accurate dating of sedimentary rocks and fossils
- they decay at a predictable rate: level of radiation dies down over time
- measuring the radiation now and its ‘half-life’, work at approx. age
- can predict entire history of life with good accuracy
- eg. Carbon 14 > 40 000 years
11
Q
electron microscope:
A
- able to study fossil cells in rock, make comparisons to ‘primitive cells’ which live today
- eg. archaea bacteria, very tolerant species
12
Q
biochemical analysis and DNA technology:
A
- can identify remains
- find ‘relatedness’ of different organisms, estimate when the species divided
- eg. chimpanzees and humans diverged only 5 million years ago
- show all life forms are related, support evolution
13
Q
deep sea observation:
A
- advanced technology
- observed hypothermal vents in 1979
- provide optimum heat allowing organic chemistry to occur
- spews out large volumes of nutrient and chemicals, which bacteria use in process of chemosynthesis in harsh environments
- instead of photosynthesis
14
Q
name the 7 major stages of evolution of living things:
A
- organic molecules
- membrane formation
- heterotrophic prokaryotes
- autotrophic prokaryotes
- eukaryotes
- colonial organisms
- multicellular organisms
15
Q
7 major stages of evolution of living things: organic molecules
A
- 4.5 billion years ago
- formation of organic molecules from inorganic
- amino acids formed proteins, nucleotides etc.
- evidence: Urey-Miller experiment, alternately panspermia
16
Q
7 major stages of evolution of living things: membrane formation
A
- 4 - 3.5 billion years ago
- molecules were indistinguishable soup of gases, molecules
- needed separate metabolic reactions so valuable metabolites can be used by itself
- once formed, able to form cells and natural selection was possible
- evidence: all cells are lipid based membranes
17
Q
7 major stages of evolution of living things: heterotrophic prokaryotes
A
- 3.5 - 2.5 billion years ago
- simplest unicellular organisms
- no organelles
- bacteria are most heterotrophic
- use energy from surroundings to make own compounds
- evidence: microfossils
18
Q
7 major stages of evolution of living things: autotrophic prokaryotes
A
- 2.5 - 2 billion years ago
- selective pressure for cell advantage: make own food
- cyanobacteria, trap solar energy in chlorophyll using photosynthesis to produce own food
- carbon dioxide + water –> glucose + oxygen
- production of oxygen now in atmosphere
- from anoxic –> an oxic environment
- evidence: stromatolites
19
Q
7 major stages of evolution of living things: eukaryotes
A
- 1.5 billion years ago
- organisms with membrane-bound organelles
- hypothesise endosymbiosis: internal relationship dependant on each other
- postulated by larger cells engulfing smaller cell –> developed relationship
- evidence: mitochondria and chloroplasts (similar to cyanobacteria) have own DNA, endosymbiosis
20
Q
7 major stages of evolution of living things: colonial relationship
A
- 1.5 billion years ago
- as eukaryotic cells developed, natural selection began diversity based on immediate environment
- some cells divided, yet some remained close together and synchronised: colonial organisms
- eg. volvox (green algae) exists as large clump and syncs the beating of flagella (tail) to move colony
- eg. slime mould: has individual stage but will colonise if resources deteriorate
- evidence: still alive today: corals
21
Q
7 major stages of evolution of living things: multicellular organisms
A
- 1 - 0.5 billion years ago
- allowed development of plant, animals and fungi
- 3 possiibilties:
- loose associations between cells in colonial organisms become permanent
- unicellular organisms undegone repeated cell divisions without cytoplasmic divisions
- unicellular organisms undergone normal cell division but remained attached to each other to form 3D multicellular organisms
- evidence: US! DNA, fossil record, structural anatomy
22
Q
paleontology:
A
- study of prehistorical life through fossils
23
Q
2 types of early fossils:
A
microfossils:
- similar to single celled prokaryotes
- eg. bacteria and proteus
stromatolites:
- layers of prokaryotic cells called cyanobacteria
- called autotrophic prokaryotes (photosynthesis)
- seen in Shark Bay
24
Q
geology:
A
study of earths crust and rocks
25
3 main rock types:
igneous:
- crystalline solids formed from cooling magma
- they do contain uranium, NO LEAD
- can be compared by levels of uranium -> lead, also to sedimentary rocks above/below
- eg. granite NEW
sedimentary:
- layers of debris compacted and cemented together
- eg. limestone (crustaceans and shells) OLDEST
metamorphic:
- rock which changes form, due to pressure
- eg. any NO EXACT AGE
26
- how does oxygen help
- iron bands in rock formations: when oxygen was first produced, made distinct red bands as iron reacted
27
fossil types:
mould:
- imprint of 'hollowed areas'
cast:
- copy/mineralised outline of organism
trace:
- sign of organisms' existance (footprint, coprolite: poo)
true form:
- actual remains of organism
28
law of superposition:
- that youngest rocks in stratified formation are at the top, meaning fossils found in these rocks died more recently than in deeper layers
29
change from anoxic to oxic environment:
- evolution of photosynthesis changed environment from anoxic --> oxic, supporting most life on earth today
- release of oxygen increased dramtically
- allowed for dramatic expansion of eukaryote organisms
- generally accepted all life orginated from aquatic environments, then moved to land
- process of phtosynthesis supporting the process of respiration was a more efficient way to gain energy --> increase size and complexity of organisms --> increase to ozone layer (o3) protection from UV light, wihtout it life could only exist underwater
30
What is taxonomy and why?
- classification of organisms
- easier to study
- separate groups with similar features
- show relationships between organisms/groups, evolutionary pathways established
- unique names for species
31
traditional biological classification:
- based on MORPHOLOGY: structure of organisms and cells
- organisms with similar morphology are grouped
advantage:
- stays the same though life of organism
- easy to observe
- morphology often results of evolution, related species most likely ended in same group
eg. based on structural features, snakes, lizards, crocodiles are classified together, separate from birds
- however, DNA shows crocs and birds are more closely related than with lizards/snakes
32
Cladistic classification:
- use of structural criteria is being improved and extended using new information from technology:
* electron microscope
* DNA and biochemical studies
- DNA and protein sequencing determine 'relatedness' of species in evolutionary sense
- based more on evolutionary pathways called 'cladistic classification'
advantages:
- groupings are true 'family trees'
- as fossil discoveries and new technology reveal more details about evolutionary relationships, traditional morphological classification is becoming more cladistic
33
classification hierarchy:
```
Domain Dang
Kingdom Kevin
Phylum Please
Class Come
Order Over
Family For
Genus Gay
Species Sex
```
34
Kingdoms:
- Animalia
- Plantae
- Fungi
- Protista
- Monera: Archaea/Eurbacteria
35
binomial system:
- 2 naming system for species:
- eg. human: homo sapiens
- species from same genus are closely related, share similar characteristics
- eg. Felis leo (lion), Felis tigris (tiger)
36
what defines a species?
- all higher taxon levels, body and cell structures used to separate the groups
- same genus are similar in body structure that reproduction is used to define species
Species:
two organisms are considered belonging to same species if they normally interbreed and produce healthy fertile offspring
eg. between dogs
37
classifying extinct organisms: problems
- our biological classification scheme is used not only for modern species but extinct ones also
- scientists believe 99% of species are now extinct, evidence from fossil record (imprints and remains preserved in sedimentary rock)
by classifying from fossils alone:
- modern classification relies on cell structures at some taxons
- most fossil imprints and cell details were not preserved
- new DNA tech and biochemical analysis are good for 'relatedness' between alive organisms, but cannot be used on fossils
- don't have organic molecules anymore
- very ancient/small fossils are impossible to classify with DNA samples and well preserved cellular prints
- very rare, and most DNA samples don't survive fossilation
