Evidence for Evolution (10.2) Flashcards
State what evolution is a process of
Change
State what the modern theory of evolution states
All living organisms share a common origin 3.8-4.1 billion years ago
Describe palaeontology
Study of ancient life represented by fossils
Describe fossils
Preserved remains, impressions or traces of organisms found on the surface of Earth
Describe amber
Fossilised tree sap
State what preserved remains are usually
Hard structures that are not easily destroyed/slow to decompose
Provide some examples of commonly preserved remains
Bone, shell, wood, leaves, pollen, spores
Describe what the fossil record refers to
The total number of fossils discovered
State what the fossil record provides evidence of
The evolution of living organisms through geological time
State what fossils tell paleontologists and palaeobotanists about
The kind of organisms and their interactions with Earth
State what the fossil record allows humans to do
Put a time scale on evolution
Describe fossilisation
Preservation of the hardened remains or traces of organisms in rocks
State what the chances of an organism becoming fossilised after death can be classified as
Small
State whether or not soft-bodied organisms are unlikely to be preserved
Yes. They are unlikely to be preserved.
State why soft-bodied organisms are unlikely to be preserved
Soft body parts decay readily or are subject to predation and scavenging
State when fossilisation has a chance of occuring
When an organism is buried by sediments
State what burying an organism in sediment reduces the chances of
Decay
State how burying an organism in sediment reduces the chance of decay
Reduces oxygen exposure for decomposer microorganisms and hides from scavengers
State what occurs when sediments of sand, silt or mud in the sea, a lake or slow-flowing stream accumulate over the organism
The organism is preserved
State what the weight of many layers of sediments squeezes out
Water between the particles of sand, silt or mud
State what occurs as the deposit deepens in the sediment
Temperature increases and soft sediments become solid rock
State where sediments generally accummulate
Water bodies
State where a large proportion of fossils are found
Ancient bodies of water once existed
State whether or not organisms on land are less likely to be preserved than those that live in aquatic environments
Yes
State whether or not delicate plant parts, such as flowers, are rarely fossilised
Yes. Flowers are rarely fossilised.
State whether or not the fossil record is biased
Yes.
State to what the fossil record is biased to
Certain parts of/whole organisms and certain environmental conditions
State what the bias of the fossil record limits
Evidence of past life and our understanding of it
List the 4 major types of fossils
- impression fossils
- mineralised fossils
- trace fossils
- mummified organisms
Describe impression fossils
Fossils where only the shape/impression of the structure remains
State what occurs to impression fossils in limestone rocks
Fossil retains 3D shape
State what occurs to impression fossils in shale rocks
Physically compressed and fossils are flattened
State what is formed if the vacant space of an impression mould is later filled with foreign material
3D ‘sculpture’ of the organism is formed
State what the 3D ‘sculptures’ of impression organisms are referred to as
Cast fossils
Describe trace fossils
Fossils preserving evidence of activity/behaviour, without containing parts of the organism
State whether or not trace fossils contain parts of the organism
No
Provide 2 examples of trace fossils
- Casts of burrows
2. Footprints
Describe mummified organisms
Fossils trapped in a substance under conditions that reduce decay.
Provide 2 examples of mummified organisms
- Insects trapped in amber
2. Animals frozen in ice
Describe mineralised fossils
Fossils that occur when minerals replace the spaces in structures of organisms
State what minerals eventually replace in mineralised fossils
May replace the entire organism
State what is left when minerals replace mineralised fossils
Replica of the original fossil
State what the process of minerals replacing an entire organism is referred to as
Petrification/Mineralisation
Provide 3 examples of minerals involved in the fossilisation of some organisms
- opal
- pyrite
- silica
Provide 1 example of a mineralised fossil
- Petrified wood
State 2 ways the age of a fossil can be determined
- Relative dating
2. Absolute dating
Describe relative dating
Dating based on statigraphy
Describe statigraphy
Study of the relative positions of the rock strata, or layers of rock which contain fossils
State what the age of the lowermost strata is
Oldest
State what the age of the highermost strata is
Youngest
State what the age of a fossil is estimated relative to
Known age of the layers of rock above and below the layer in which the fossil is found
State in what regions relative dating can be difficult
In regions where rock layers have eroded, buckled, moved or reburied
State what the eroding, buckling, moving or reburying of rock strata can result in
Alteration in the original sequence of strata
Describe an index fossil
Fossil used to define and identify geological periods
State where index fossils are often found
In similar sites to which an absolute age has been determined
Provide 1 example of an index fossil in Europe
Ammonoids (extinct molluscs)
Describe absolute dating
Quantitative method of determining the age of a rock or object using radioactivity
State what absolute dating provides in comparison to relative dating
More precise estimate of age
State whether or not absolute dating will also provide an exact date
No
State the 2 classifications of absolute dating methods
- Radioisotopic
2. Non-radioisotopic
State what radioactive elements decay into
Different forms
State at what rate radioactive elements decay into different forms
Rates that are constant for a particular element
State what the rate of decay of a particular element is independent of
The nature of the rocks or the environmental conditions to which they are exposed
Describe the half-life of a radioactive element
Time taken for half the original quantity of the radioisotope to decay
State what the half-life of a radioactive element can be used to calculate
The age of the rock in which it is contained
Describe structural morphology
Study of the form and structure of organisms
State what structural morphology gives an insight into
Relationships between species
State what the field of comparing structures of organisms is referred to
Comparative morphology or comparative anatomy
State what features of organisms that have a fundamental similarity based on a common ancestry are called
Homologous features
State what homologous features evolve
Different functions
State what the similar structures of species provide evidence of
Organisms shared a common ancestor from which they diverged over time
Describe divergent evolution
The evolution of two or more different species from a common ancestral species
State what mutations in the genetic sequences regulating the length of bones in a limb can result in
The limb being used in different ways
Provide 1 example of homologous features
Forearms of humans, cats, whales and bats (Pentadactyl limb)
State what homologous features are evident in
Groups of organisms that share a common ancestor
Describe analogous features
Features that serve the same function but have evolved independently
State why analogous features may evolve
Unrelated organisms have experienced similar selective pressures
State what biologists must distinguish between when they attempt to determine evolutionary relationships
Homologous and analogous features
State when convergent evolution occurs
When similar features evolve independently in unrelated groups of organisms
Describe vestigial organs/structures
Structures that are remnants of organs that had a function in ancestral species but have become reduced in size due to lack of use over time
Provide 3 examples of vestigial organs/structures
- wisdom teeth
- inner eyelids
- ear muscles
State what the comparison of organisms is complicated by
The way organisms change substantially between life stages
Provide the name of the field of biology that studies the process of how organisms change from a zygote to adult
Developmental biology
Describe development biology
Study of evolutionary relationships of the same stage of development and comparison between organisms
State what organisms that share a common ancestor also share
Similar master genes
Describe comparative embryology
Source of evidence of evolutionary relationships
State what comparative embryology is based upon
The passing of the embryo through similar stages of development
Describe stromatolites
Dome/mound built up of layers of lime-secreting cyanobacteria and trapped sediment
State the 4 methods of radioisotopic dating
- Fission track
- Radiocarbon
- Pottasium/Argon
- Uranium series
State the 6 methods of non-isotopic dating
- Palaeomagnetism
- Thermoluminescence
- ESR
- Amino acid racemisation
- Varve
- Tree-ring
Describe fission track dating
Uranium-235 sometimes undergoes spontaneous fission and the subatomic particles emitted leave tracks through nearby mineral
State the dating range of fission track dating
100 million-5000 years
Provide some examples of materials datable by the fission track method
Pottery, glass, volcanic materials
Describe radiocarbon dating
Measure of the loss of the isotope carbon-14 taken up by an organism when it was alive
State the dating range of radiocarbon dating
50,000-1,500 years
Provide some examples of materials datable by the radiocarbon dating method
Wood, shell, peat, charcoal, bone, animal tissue, soil
Describe potassium-argon dating
Measure K-40 to Ar-40 decay in volcanic rocks lying above or below fossil bearing strata
State the dating range of potassium-argon dating
100 million-50,000 years
Provide some examples of materials datable by the potassium-argon dating method
Volcanic rocks and minerals
Describe uranium series dating
Measure of the decay of U-235 and U-238 into Th-230 and U-234 respectively
State the dating range of uranium series dating
1 million-1500 years
Describe palaeomagnetism
Shows the alignment of the Earth’s magnetic field when the rock sample was last heated above a critical level
Describe thermoluminescence
Measure of the light emitted by a sample of quartz/zircon grains that have been exposed to sunlight or fire in the distant past
Describe ESR
Measure of the microwave energy absorbed by samples previously heated or exposed to sunlight in the distant past
Describe amino acid racemisation
Measure of the gradual conversion of left- to right-handed amino acid isomers in the proteins preserved in organic remains
Describe varve
Measure of the annually deposited sediment layers (varves) found in many lakes
Describe tree-ring
Measure of the annual growth rings of trees
State what tree ring estimates can be cross referenced to
Carbon dating
Describe radiometric dating
Quantitative technique used to determine the proportion of particular isotopes within rocks around or within the fossil
State to what year carbon dating can be used to estimate the age of samples
60000 years
State what the method of radioactive carbon dating is limited to
Samples that are not older than 60000 years
State why radioactive carbon dating is limited to samples that are not older than 60000 years
Because after that time period, there is very little carbon-14 left in the fossil
State what type of radiometric dating technique can be used in place of radioactive carbon dating for samples older than 60000 years
Potassium-argon dating
State the limit of thermoluminescence dating
500000 years
State what the amount of light emitted from an object when thermoluminescently dated is equivalent to
Amount of radiation absorbed by an object
State the specific substance whose age is determined via ESR
Calcium carbonate in limestone, coral, fossil teeth, molluscs and egg schells
State whether or not samples are destroyed by ESR
No
State whether or not samples are destroyed by thermoluminescence dating
Yes
State what type of technique electron spin resonance is considered
A spectroscopic technique
State what ESR detects
Atoms with orbitals containing unpaired electrons
State the 4 major stages of fossilisation
- Organism death
- Decay of soft tissue and burial
- Sediment accumulation
- Uplift, erosion and exposure
Describe fossil record
The remains/imprints of organisms from earlier geological periods preserved in sedimentary rock.
State why fossilisation is a rare event
Rapid burial and suspension of the normal processes of decay must occur for fossilisation to be conducted
Describe convergent evolution
The evolution of similar features in unrelated groups of organisms.
State what features convergent evolution can be paired with
Analogous features
Provide 1 example of analogous features
Fishes and dolphins have streamlined bodies
State what features divergent evolution can be paired with
Homologous features
Describe macroevolution
Evolutionary change, often of whole taxonomic groups
Describe homeotic genes
Genes regulating development of anatomical structures.
Describe master genes
DNA sequences that control formation of proteins necessary for large scale, embryonic development
Describe coevolution
Two or more species evolve in tandem by exerting selection pressures on each other.
Describe microevolution
Change in allele frequencies that occurs over time within a population.
State 2 common types of relative dating methods
- Index fossils
2. Statigraphy
Describe hox genes
Group of related genes that specify regions of the body plan of an embryo along head-tail axis.
