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year 12 biology > Topic 11 > Flashcards

Topic 11 Flashcards

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AP® Biology flashcards
1
Q

evolution

A

gradual adaptive change over geological time, in composition of populations from ancestral species to new species
-changes to DNA through mutations occur over long time period-introduce new alleles-changing genotypic frequency-changing phenotypic frequency

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2
Q

microevolution

A

small scale changes within a gene pool of population of species over time

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3
Q

macroevolution

A

large scale changes involving species over time- new species evolves

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4
Q

relative dating technique

A
  • process depends on stratification- formation of sedimentary layers of rock
  • principle of superposition- older layer rocks are at bottom of strata sequence -overlain by younger layers
  • gives relative age
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5
Q

stratigraphy

A

relative age of fossil is determined by position of stratum

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6
Q

principle of correlation

A
  • index fossils-fossils of species existed during limited periods of geological time and found in restricted depth of strata- used as guides to age of rocks in which they are preserved
  • presence of index fossil in different regions will be deemed to be same age
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7
Q

characteristics of index fossils

A

abundant, distinct, geographically widespread, found in many rock kinds, narrow in strata range

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8
Q

absolute dating technique

A

radiometric dating is a technique in which actual age of fossils and rocks is expressed in years
-radioactive decay of some elements- used to establish absolute age of fossils and rocks

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9
Q

potassium-argon dating

A
  • potassium 40 decays into argon 40

- has long half life- can be used to date rocks and fossils that are over 3 billion years old

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10
Q

carbon dating

A
  • fossils that contain organic matter, and are no older than 60,000 years old- can be dated using radioactive carbon dating
  • carbon-14 decomposes after death due to radioactive decay
  • longer since dead- lower ratio of carbon 14 to carbon 12
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11
Q

fossil record

A

-fossils provide evidence of organisms that once lived on this planet

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12
Q

physical fossils

A
  • remains or whole of part of structures of organisms
  • organic material of these structures is replaced by mineral or organic matter has disappeared and organism simply exists as impression
  • decomposition happens quickly after death
  • decomposers and scavengers get rid of soft tissue’
  • weathering gets rid of bones
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13
Q

fossilisation

A

process of preserving whole or part of organism, which lived in the past

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14
Q

trace fossils

A

-preserved evidence of activities of organism, such as footprints, tooth marks, tracks, burrows and coprolites- fossilised dung

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15
Q

biosignatures

A

physical or chemical sign preserved in minerals, rocks or sediments that can be inferred to be cellular or to have resulted from organisms metabolic activity

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16
Q

steps in fossil formation

A
  • mineralisation is required for fossilisation-unless in ice or sap
  • fossilisation occurs best in sap/ice then marine, then freshwater then terrestrial
  • hard parts of body fossilise best
  • organism dies and buried rapidly by volcanic ash, sediment, mud or silt- protects organism from scavengers and decay
  • rate of decay is slow in reduced oxygen/light and temperature
  • layers of material build up over top of organism- exerting pressure on remains
  • weight of overlying sediments compresses original sediment layer so that it become rock
  • mud becomes mudstone, sand becomes sandstone and volcanic ash becomes tuff
  • organism could also decompose slowly- leaves cavity called mould
  • mould becomes filled with minerals and hardens- forming cast of original organism
  • cast is 3D model of organism- original tissue replaced by carbon or minerals
  • repeated layers bury fossil- right temperature and pressure forms rock around fossil- strata forms
  • results in formation of different rock types with different fossils embedded in it
  • hard parts of organism are already hard and mineralised- fossilise well
  • imprints may also fossilise- due to sediments covering and filling imprint- later pressure resulting in rock formation
17
Q

why fossil record is incomplete

A

not all organisms die in areas that favour fossilisation- may decompose too quickly

  • scavengers may consume and destroy organisms- fossilisation wont occur
  • soft bodied organisms- not easily fossilised- cant mineralise
  • earth movements and lava can destroy fossils- make them inaccesible
18
Q

conclusions drawn from fossil record

A
  • fossilisation is a rare event
  • structure and arrangement of skeleton or bones- suggest size, shape, mode of locomotion and habitat
  • structure and arrangement of teeth- suggests diet and type of organism
  • evolution occurs from simple to more complex forms
  • different change in environments have influenced evolution in species over time
19
Q

transitional fossils

A

-if new species evolved from ancestral species- intermediate fossil evidence must exist that has characteristics of both ancestral and present forms of species.

20
Q

homology- similar structures

A
  • believed all vertebrates evolved from common ancestors
  • pentadactyl limb is found on most vertebrates has similar structure-homology
  • evolution occurs by modifying pre-exisiting structures
  • homologous structures are those similar in structure but can sometimes serve different function
21
Q

vestigial organs

A
  • functionless organs that were present and functional in ancestors
  • over millions of years- pelvis and femur have become very small- no longer fulfil locomotion function
  • presence of vestigial hind limbs in whales- supports evolution of whale from four limbed terrestrial mammal
22
Q

developmental biology

A
  • comparison of development of embryos- provides evolution evidence
  • pharyngeal arches present in all vertebrate embryos- develop into different adult structures
  • tail also found in embryos and adult vertebrates
  • suggests all vertebrates share a common ancestor

year 12 biology (16 decks)

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