History of life on earth 12 Flashcards
Timeline of Earth ( PEMALMDg)
- prokaryotes
- eukaryotes
- Multicellular ( multicellular ogranism are common)
- Animals ( Cambrian explosion) ( 1st vertebrate land animals)
- land plants ( 1st flowering plants)
- mammals
- Dinosaurs
- Genus Homo
Cambrain
Period of time where life rapidly diversified and new living groups evolved. Tribolites first emerged
Stromatolites
——– are the earliest evidence of living things on earth
Prokaryotes
are cells with a circular DNA and no membrane-bound organelles
Flowering plants
the type of plant that emerged after plants that could reproduce with spores and cones
Trilobite
any member of a group of extinct fossil arthropods easily recognized by their distinctive three-lobed, three-segmented form
______I______ emerged after ______II______ via the process of endosymbiosis, whereby first ______III______ bacteria and then ______IV______ bacteria were engulfed but not destroyed by a host cell.
EUKARYOTES emerged after PROKARYOTES via the process of endosymbiosis, whereby first RESPIRING bacteria and then PHOTOSYNTHESISING bacteria were engulfed but not destroyed by a host cell.
Arthropods
is an animal without a back bone, with six or more jointed legs, a segmented body and a supporting structure on the outside.
Examples of Organism that evolved on earth during the Cambrian period
The Cambrian period was after the Precambrian era and the Ediacaran period. Describe an organism that evolved on Earth during the Cambrian period
Hallucogenia. Arthropods. Molluscs. Gastropods. Jawless fish/early vertebrates.
response:
- Trilobites evolved during the Cambrian explosion.
- They were arthropods with hard shells and a bilaterally symmetrical body plan.
Some stromatolites have been dated to 3500 mya. Would these stromatolites have been formed by prokaryotic or eukaryotic organisms? Justify your response.
- Stromatolites would have been prokaryotes, because they existed before eukaryotes evolved.
Explain why developing an oxygen-rich atmosphere was important to the development of life on Earth.
- Increasing the oxygen concentration in the atmosphere=>more living things can respire aerobically + organisms can make more energy a+larger organisms can survive.
- In addition, oxygen forms the ozone layer which protects living things from harmful UV radiation.
Using your understanding of endosymbiosis, explain how cyanobacteria were crucial for the evolution of multicellular land plants like the mountain ash.
- Once, an ancestor of mountain ash was a eukaryote that lacked chloroplasts.
- This eukaryote engulfed a photosynthetic cyanobacteria-like prokaryote,
- then used it to make glucose rather than destroying it. I
- In this way, early chloroplasts were formed inside the first eukaryotes.
- This cell replicated and evolved over billions of years, passing on its chloroplasts, until it eventually speciated into mountain ash
identify similarites and one differences between the cells of cyanobacteria and mountain ash
Other acceptable similarities include: Both have cell walls. Both have cell membranes. Both have genetic material in the form of DNA. Both have ribosomes. Both undergo respiration.
Other acceptable differences include:
Mountain ashes have differentiated cells with specialised functions, cyanobacteria do not.
Mountain ashes have membrane-bound organelles, cyanobacteria do not.
Mountain ashes are multicellular, cyanobacteria are not.
Mountain ashes have linear DNA in a nucleus, cyanobacteria have circular DNA in a nucleoid region.
Mountain ashes have cellulose cell walls but cyanobacteria have peptidoglycan cell walls.
Explain the consequences of poor replicability.
By not replicating their experiment,
- we do not know if the results are reproducible
- or if they just happened by chance.
- This means their results are not reliable
Fossils
the preserved body,
impressions, or traces of an
ancient organism
- permineralised, trace, mummified, impression
Steps in fossilation ( making a fossil) example of died dinosaur
- The organism dies in a river
- The body is covered with
sediment. The soft tissues
decompose, and the hard body
structures become fossilized by
permineralization. - The sedimentary layers
accumulate - Earth’s movements raise
the layers of the rocks to the
surface. - The rock erodes, exposing the
fossilised body structures.
Fossilation
the process by which
an organism becomes a fossil
sedimentary rock
rock that has
formed through the accumulation
of sediment and hardening under
pressure
Conditions that reduce the rate of decomposition typically increase an organism’s chance
of becoming fossilised.
- areas of rapid sediment accumulation
- constant cool temperatures
- low light availability
- physical protection from scavengers and decomposers (e.g. fungi, bacteria).
For example, as aquatic systems regularly deposit large amounts of sediment, many aquatic
animals and plants are preserved.
List 4 type of fossils
- Perminerlised fossils ( mineralised fossil)
- impression fossil
- trace fossil
- Mummified fossil
Permineralised fossil( Mineralised fossils)
formed when organic matter is gradually replaced by hard minerals. Also known as a
mineralised fossil
Impression fossil
organism is encased in material but decomposes or is removed and the gap is filled with another substance. Also known as cast and mould fossils
- they show the shape of the ancient organism but no organic material is preserved
Trace fossil
(footprints / burrows / faeces/ nest or tracks) not part of any organism, but they are preserved evidence of an organism’s activity / behaviour/ presence
Mummified fossil
List how - This occurs through factors that reduce decay
a fossil formed when the body is under conditions that slow down or stop the
decaying process
- Constant humidity,
- Cool temperatures
- Lack of decomposers or scavengers
- Low winds,
- Darkness are all factors that can reduce the rate of decay
e.g. found trap in tree sap, frozen in ice or in dry caves.
radiometric dating
- determine the absolute age of a fossil
- by measuring the relative amounts of radioisotopes to their products
- All radioactive isotopes have a fixed rate of decay – Half Life (number of years it takes for 50% of original
sample to decay)
Process of fossilisation
- Organism dies and falls to Earth’s surface
- The remains are quickly covered with sediment which minimizes scavengers and decay
- Over millions of years the sediment compiles, compacts and turns into sedimentary rock, preserving the
organism’s hard parts - Erosion exposes the fossil to be found
Absolute dating and examples
calculate the absolute age of a fossil by providing an estimate age of fossil or rock.
e. g.
- luminescence
- Electron spin
- Resonance
- Radiometric dating methods,
Relative age
- The age of a fossil is determined by comparing to other fossils with each other
- Instead of a fossil’s age in years
e. g. - fossil succession/ law of superposition and index fossil
strata
separate layers within sedimentary rock
fossil succession
- the principle that fossils of
- the same age will be in the same layer of sedimentary
rock, a - nd fossils found in a higher or lower sedimentary layer will be younger or older respectively. Also
known as the law of superposition
index fossil
- a group of widespread and distinct fossils
- which existed for a known short period and have a known ages.
- thus,an be used as a reference to easily determine the age of unknown fossils close to index fossils in sedimentary layers.
summary of radiometric dating pathways commnly assessed by VCAA
Carbon-14 –nitrogen-14: 1000-50,000 year
Uranium-235 –lead-207:700Million years
Uranium-238 –lead-206:4.5 Billion years
Potassium-40 –argon-40:1.3 billion years( used for igneous ash)
half-life
the time taken for half the
mass of a radioisotope to break
down into its products
fossilisation bias
Certain organisms are more likely to be
fossilised, based on physical and behavioural characteristics
supercontinent
a massive historical landmass (e.g. Pangaea, Gondwana, Laurasia) that broke apart to form the modern continents
tectonic plates
Earth’s outer crust is divided into tectonic plates that float on the magma below. These movements explain several natural phenomena, including earthquakes and mountain range formation
continental drift
the movement of
tectonic plates around Earth over
millions of years
Chordata
a group of animals
including fish, amphibians, birds,
reptiles, and mammals. Also
known as chordates
- features of chordata:
- -> Pharyngeal arches, Dorsal nerve cord, Notochord, Post anal tail
embryo
a stage of offspring
development, not unique
to chordates
Biogeography:
- The study of the distribution of species in geographical space over time
- Offers insights into how species evolved
- Relies on continental drift (Pangea), and theory that every species originates from one place and spread/migrate throughout the world
- continental drift explains how Fossils of same species can exist on different continents
Developmental Biology:
- The study of organisms at different stages of development
- May reveal physiological, structural and chemical features that inform patterns of evolution, more similarities – the more closely related
Ex: Comparative embryology – the study of comparison of embryos
Closer related organisms go through similar stages in embryonic development, specialised features develop later than generalized features.
- e.g All embryos of aquatic and terrestrial vertebrates have gill slits – common ancestor
adaptive radiation
rapid divergent evolution, producing a wide array of species/forms
Structural Morphology/ Comparative anatomy
Comparative anatomy, study of anatomical structures as evidence for biological change
Help informs patterns of evolution (homologous, analogous, vestigial)
homologous structure
a structure present in two or more species that may look and function very differently in each species ( bc selection pressures) , but is derived from a common ancestor
vestigial structure
- a part of an organism that has lost all or most of its usefulness
- as a result of evolution by natural selection
- e.g. pelvic bone in whales
analogous structure
a structure present in two or more species that fulfils the same function but does not originate from a common ancestor
e.g. Evidence for convergent evolution
Ex: Wings
Ancestral birds, mammals and reptiles show wings as they needed to fly , however bone structure are not
similar
background extinction rate
expected rate of extinctions within
a geographic area
mass extinction
- period of rapid species extinction,
- reducing biodiversity
- Evident when the extinction rate is much greater than the background extinction
rate
Evolution:
the process by which over geological time, the heritable traits of the individual of a population
change leading to new species. It requires phenotypical variation due to genotypic variation, selective
pressure and hence a selective advantage, reproductive isolation and long generational time.
Divergent evolution:
- When a species diverges over time into two different species resulting in species
becoming less like the original one - A recent common ancestor evolves separately into two or more species developing different adaptations in response to different selection pressures.
> adaptive radiation – rapid divergent evolution of a large number of related species, caused by rapid speciation after organisms evolve different adaptations in response to new conditions and
opportunities results in a wide diversity of species with unique adaptations to the environment
Convergent Evolution:
- Distantly related species without a common ancestor evolve similar adaptations in response to similar selection pressures.
- Don’t share a RECENT common ancestor
May have similar environments.
Extinction
- The process of death of all members of a species.
- Caused by environmental, competitive, predatory or human intervention factors.
Mass extinction – the loss of many different species at the same time
Conservation techniques:
Breeding with different populations
Captive breeding programs, habitat conservation, excluding fences
transitional fossil
a fossil that shows characteristic of both recent and ancient groups of life
Explain how the presence of these features( Dorsal nerve cord and Pharyngeal arches) during the early development of chordates supports the theory of evolution.
- This feature is only present in chordates, - implying that their early development is both similar within the phylum Chordata and different to the early development of other phyla.
- This suggests that all chordates share a common ancestor and have gradually acquired changes since then.
The fossil Archaeopteryx has features resembling both ancient dinosaurs and modern birds.
What type of fossil does Archaeopteryx represent, and what does this suggest about the evolutionary origins of modern birds?
- The 𝘈𝘳𝘤𝘩𝘦𝘰𝘱𝘵𝘦𝘳𝘺𝘹 fossil is a transitional fossil between ancient dinosaurs and modern birds.
- This indicates that dinosaurs are the ancestors of modern birds.
Explain how these dating techniques, (radiometric dating) techniques allow scientists to establish the age of fossils.
- A radioisotope within a fossil loses half of its mass at a predictable rate called a half-life.
- By measuring the relative amounts of this material and its breakdown product, and given the half-life of the material, the absolute age of the sample can be calculated.
What absolute dating pathway would have been used to determine the age of the igneous ash?
Ash is of igneous origin. Therefore, potassium-40 would have been used to calculate the absolute age of the ash
Look at question 15 a.b in book
Yes I understand
Example of causes of divergent evolution that leads to speciation
- different selection pressures
- genetic drift shifting the population genome over an extended amount of time
- allopatric speciation
List general causes of mass extinction
- due to strong selective pressures,
- widespread environmental shift
- or natural disaster
Read:
- Periods of mass extinction in history and cause
- The Ordovician event: Highly variable weather patterns
- The Denovian event: Global cooling followed by global warming
- The Permian event: High volcanic activity + global warming, rapidly changing ocean chemistry
- The Triassic event: High atmospheric CO2 causing global warming and
shifting ocean chemistry - The Cretaceous event: Asteroid impact causing rapid global cooling
Mass extinctions is commonly followed by a rapid period of_______
divergent evolution/ period of adaptive radiation
Snakes said to come from lizards:
How did natural selection produce vestigial limbs in modern snakes?
- snakes evolved from legged lizards, however fully formed legs were disadvantageous for movement
- As smaller legged individuals were favoured and repeated selection resulted in the almost complete removal of limbs in modern snakes
- As these vestigial limbs provide no selective advantage or disadvantage, they remain present throughout subsequent generations.
Explain how the scientists calculated the age of the igneous sedimentary rock.
- As the sedimentary layer is of igneous origin, the scientists could calculate the age via radiometric dating
- using the potassium-40 pathway.
- By measuring the relative amount of potassium-40 and stable products of the radioactive pathway, the absolute age of the rock can be calculated
Explain how these species independently evolved the ability to glide.
- Australian Sugar Glider and North American flying squirrel both have the wing flaps but don’t have commone ancestors
- These two species do not share a recent common ancestor, as they evolved from completely different lineages.
- However, both of these species have adapted to fill similar niches, and experience similar selective pressures.
- Gliding between trees is an efficient way of moving between trees, and removes the threat of ground-dwelling predators.
- As such, individuals with greater gliding ability are able to reproduce more, repeated selection over generations
- has facilitated the independent evolution of the analogous structure of skin extensions/ wing flap.
Compare the explosive and long-fused models, and whether this supports the classical view of adaptive radiation. Give evidence from the text to support your answer. ( Q 19e) - do again and read
yes I did do
- The fossil record indicates placental mammalian life rapidly diversified shortly after the extinction of the dinosaurs during the K-pg mass extinction.
- This aligns with the explosive model and our classic view of adaptive radiation following a mass extinction.
- In contrast, the more recent molecular analysis and long-fuse model suggest diversification may have begun 20 million years before the K-pg event, while dinosaurs were still alive.
- This indicates mammalian radiation occurred despite niches already being occupied, which contradicts the classic view of adaptive radiation.
Conditions in Caves for fossilizations to occur
- Constant cool temperature
- constant humidity
- Lack of light and wind and water
- lack of decomposers or scavengers.
Conditions near coast of Australia
- Rapid burial in sediment
- Lack of oxygen,
- Lack of decomposers and scavengers.
- Submeraged in highly mineralised ground water
What is the name given to the study of similar or different structures found between the bones and skeletal structures of animals, including fossilised remains?
Structural morphology/ comparative anatomy
Discuss the evidence the scientists would have used to support this conclusion. Use an example from the skulls in your response.
- Finding homologous structures between the skulls would indicate the two species are related.
- The lower jaw structure appears to be homologous between the two species as it is a similar shape
- for these type of question just talk about similar features and call them homologous structures.
Explain a difference between absolute and relative dating techniques.
- In absolute dating, the age is calculated very accurately, usually by measuring relative amounts of known materials within the fossils.
- In comparison, relative dating approximates a fossil’s age by associating it with another specimen within the same or another sedimentary layer
what doe control group do in an investigation
- The scientists’ results are more reliable for using a control.
- This is because they have ensured that the proportion of bacterial forms (the dependent variable) is caused by exposure to a predator (the independent variable), rather than the effects of other variables.
Read: According to current understandings, could a similar bacterial aggregate be an ancestor to all modern multicellular life? Explain.
- No.
- While this bacteria does aggregate into a multicellular form, the lack of membrane-bound organelles indicate this bacteria is still a prokaryote.
- Current understandings suggests that eukaryotes evolved membrane-bound organelles ~2 bya, and these eukaryotes then evolved multicellularity ~900 mya.
Look at 12 Review: 21 A)
yes I did thank you
