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Bio 3/4 > unit 4 aos 2 > Flashcards

unit 4 aos 2 Flashcards

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Biology 101 flashcards
1
Q

gene pool

A

the total genetic diversity (alleles) in a population
> greater genetic diversity = larger gene pool

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2
Q

genetic diversity

A
  • the variation in alleles in a population
  • occurs due to sexual reproduction through independent assortment and genetic recombination
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3
Q

allele frequency

A
  • allele = alternative form of a gene
  • calculated by counting all the specific alleles and dividing by total number of alleles
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4
Q

mutations

A
  • random, unpredictable change to the DNA of an organism
  • source of new alleles, causing diversity in the same species
  • can be spontaneous or induced
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5
Q

causes of changing allele frequencies

A
  • environmental selection pressures (natural selection)
  • genetic drift
  • gene flow
  • mutations
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6
Q

gene flow

A
  • movement of alleles from one population to another, due to individuals entering or leaving a population. Results in changes in the allele frequency of a gene pool and therefore the genetic diversity
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7
Q

genetic drift

A

a change in the allele frequency of a population due to random chance events
two types:
- bottleneck effect
- founder effect

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8
Q

bottleneck effect

A
  • change in allele frequency due to a cataclysmic event, causing a sudden drop in population (near extinction)
    > natural disasters, disease, human intervention
    causes populations to undergo new selection pressures
  • population then grows in numbers again, but allele frequency has changed as only few individuals survived, lowering genetic diversity
    > larger impact on smaller populations
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9
Q

founder effect

A

small group of individuals/ alleles is isolated from a larger population, causing them to undergo new selection pressures and form a new species
> larger impact on smaller populations

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10
Q

environmental selection pressures

A
  • environmental factors that affects the survival and reproduction of an organism
  • only organisms with favourable characteristics will survive, leading to low genetic diversity or the creation of a new species
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11
Q

natural selection

A
  • the influence of environmental pressures on allele frequency. organisms that have more favourable characteristics and are better adapted to their environment are more likely to survive and reproduce
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12
Q

adaptations

A

allow organisms to survive & reproduce within a changing environment
- structural: physical, eg. anteaters long tongue
- physiological: involves the function of organs/ systems that affect its biological fitness, eg. chameleon changing colours
- behavioural: affect how an organism behaves in itss enviro, allows it to thrive in its ecosystem, eg. male birds sing to attract females

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13
Q

consequences of changing allele frequencies

A
  • mutations can introduce new alleles to a population & increase genetic diversity
  • loss of alleles can lead to a decline in genetic diversity and possibly the creation of a new species
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14
Q

selective breeding/ artificial selection

A
  • humans select organisms to breed which carry what we deem to be desirable traits
  • causes a change in the allele frequency of the population in order to produce individuals suited to human use
  • decreases genetic diversity in a population by eliminating undesirable alleles from the gene pool
  • low genetic diversity can make populations susceptible to disease
    > selective breeding has increased dairy cows milk yield of 3750L per cow per year, to 7445L per
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15
Q

steps of selective breeding

A
  1. select desired trait
  2. breed 2 organisms with desired trait
  3. select best offspring
  4. repeat for many generations
    > takes a long period of time
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16
Q

antigenic drift

A

an accumulation of mutations over time which results in changes to the antigens on the virus’ surface

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17
Q

antigenic shift

A

an abrupt change in the genome of the virus due to swapping genetic material while in the host cell
> requires 2 viruses at once

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18
Q

antibiotic resistance

A

random mutations can occur to bacteria which give them the innate ability to tolerate an antibiotic
> these may not be killed by antibiotics, and can then reproduce, and horizontal gene transfer can occur, giving plasmids to other bacteria & creating a population of bacteria that all have resistance
> natural selection resulting in antibiotic resistant bacteria

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19
Q

treating against pathogens

A
  • vaccinations can give immunity, but can be made redundant if viruses mutate
  • antibiotics treat against bacteria, it is important to take the full course as some bacteria have mutated to be antibiotic resistant, and can survive & reproduce if full course of antibiotics isnt taken
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20
Q

the fossil record

A

evidence of evolution, shows how organisms change from simple to complex over time

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21
Q

fossil

A

preserved, hardened remains or traces of organisms within sedimentary rock

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22
Q

types of fossils

A
  • impression fossil/ mold: shape of the organism left on the rock after it has decayed
  • mineralised fossil/ petrified: minerals replace the material of the organism
  • trace fossil: record of the organisms activities, eg. footprints, burrows
  • mummified fossil: preserved in something other than rock, reduces decay
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23
Q

index fossils

A
  • abundant, distinctive fossils used as reference to determine the age of unknown fossils, have existed for a short period of time & have a known age
  • when these same fossils are found in other sedimentary layers, they can be used to date those layers
    > eg. trilobites, arthropods
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24
Q

transitional fossils

A

fossil has both primitive and derived trait, provide evidence that an ancestral species evolved
> divergent evolution
> eg. lobe finned fish transitioned from fish to amphibian

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25
Q

faunal (fossil) succession

A

fossils found in sedimentary rock succeed one another in a predictable order
> compared via index fossils found within rock layers

26
Q

relative dating

A
  • used to compare different fossils
  • if an unknown fossil is found in between 2 known layers, it can be assumed to be in between their age
  • bottom layers of sedimentary rock are older than those at the top
  • stratigraphy: the study of the age of strata (layers of sedimentary rock
27
Q

absolute dating

A
  • more precise estimate of age than relative dating, includes:
  • radiometric dating
  • thermoluminescence
  • electron spin resonance
28
Q

radiometric dating

A
  • type of absolute dating
  • carbon-14 decays into nitrogen-14.
  • carbon-14 stops being replenished in the body when an organism dies, and nitrogen-14 builds up
  • 14C decays into 14N at a known rate, so the levels of each can be compared to determine how long ago the organism died
  • works on fossils up to 60,000 years old
29
Q

speciation

A
  • species: group of organisms that are genetically similar enough to interbreed and produce fertile offspring
  • speciation: creation of a new species
    types of speciation:
    > genetic isolation
    > allopatric speciation
    > sympatric speciation
30
Q

genetic isolation

A
  • occurs when alleles are no longer exchanged between populations
  • can be prezygotic or postzygotic
31
Q

electron spin resonance

A
  • used to date limestone, coal, molluscs and eggshells
  • smashes electrons against the fossil
  • used for objects upto 300,000 years old
  • looks at calcium-carbonate impurities
32
Q

thermoluminescence

A
  • used to date objects that have been previously heated
    > eg. pottery, furnaces, archaic tools
  • more light = older age
  • can destroy the object
  • works for objects up to 500,000 years old
33
Q

prezygotic isolation

A
  • prevention of mating
  • prezygotic = before egg fertilisation
    > geological/ spatial: physical land barrier between a population
    > ecological: occupy diff ecological niches
    > temporal: timing of mating seasons don’t align
    > behavioural: diff mating rituals in animals (eg. mating calls)
    > structural: sexual organs are different or don’t fit- physically can’t mate
    > gamete mortality: egg & sperm fail to fertilise
    > sexual selection: how organisms choose mates (desirable traits)
34
Q

postzygotic isolation

A
  • prevent a zygote of 2 diff species from developing into a fertile adult
    > hybrid inviability- 2 different speacies have created a zygote but it’s not fretile due to unmatched chromosomes- (cant do mitosis)
35
Q

hybrid viability

A
  • inviability: 2 genetically similar organisms that are different species create a zygote, creates a hybrid
    > hybrid is infertile due to parents having diff amounts of chromosomes
    > eg. zebra has 64, donkey has 62, so zonkey has 63 > cant be split in meiosis
  • partially viable: lives for a while, then dies
  • sterile: viable but infertile
36
Q

allopatric speciation

A

occurs due to different selection pressures & genetic drift that occurs once a population has been split through geographic isolation, resulting in 2 different populations
> eg. Darwins finches in the galapagos islands lived in different selection pressures due to different environmental conditions, causing them to vary in size, beak shapes and food
> shows relationship between selection pressures and morphology (structure)

37
Q

adaptive radiation

A
  • form of allopatric speciation
  • refers to the rapid evolution in one place of one species into many
38
Q

sympatric speciation

A
  • the evolution of a new species from a common ancestor due to reproductive isolation while both continue to inhabit the same area
  • common in plants, uncommon in animals
  • occurs due to a mutation making an organism polyploidy (having more than 2 sets of homologous chromosomes), making them unable to reproduce with the original population, creating a new species
39
Q

Lord Howe island Howea palms - sympatric speciation

A
  • howea belmoreana (nutrient rich) and howea forsteriana (nutrient poor) both inhabit lord howe island and diverged from a common ancestor long after the island was formed
  • the two palms now grow in different nutrient level soils, causing them to have different flowering times and become reproductively isolated. develop diff mutatrions over time & evolve into different species
40
Q

structural morphology

A

looking at the similarities and differences in the structure of different species

41
Q

evidence of evolution from homologous structures

A
  • features of organisms that have the same fundamental structures, but different functions, they show evidence of common ancestry
  • eg. mammals, birds and reptiles have the same arrangement of bones in their forelimbs which all serve different functions, suggesting that these structures were inherited from a common ancestor
42
Q

evidence of evolution from analogous features

A
  • features of organisms that have the same function, but different structures, they are evidence of convergent evolution
  • the similarities are not due to common ancestry
43
Q

vestigial structure

A
  • structures that have no apparent function in a species which resemble functional structures found in its ancestor and other species
    > evidence that the organism evolved from an ancestor that needed that feature
    > eg. whale has pelvic bone, humans have muscles in their ears like those dogs have to move their ears
44
Q

molecular homology used to determine relatedness

A
  • looking at similarities in DNA and amino acid sequences between organisms to determine how related they are
    > more differences = less related
45
Q

comparing DNA sequences to determine relatedness

A

comparing DNA sequences: looks at differences in nucleotides to compare each differences in organisms
> species with fewer differences in their nucleotide base sequences have diverged from a common ancestor more recently, because there’s less time for mutations to occur in their genome

46
Q

comparing amino acid sequences to determine relatedness

A

comparing different proteins (polypeptide chains) between species
> more differences = less related, diverged a along time ago and vice versa

47
Q

molecular clock

A
  • shows how long it takes for a mutation to occur
  • uses the mutation rate of genes to determine how different two organisms are, as well as when they diverged
  • look at eg in chriso notes
48
Q

mitochondrial DNA (mtDNA)

A
  • slow mutating segment of DNA which can be used to track long term changes in humans
  • passed from mother to offspring, allows you to track maternal lineage and therefore evolution
49
Q

phylogenetic trees

A
  • branching diagrams that show evolutionary relationships between groups of organisms
  • root: start, shows common ancestor
  • branch: each line of tree
  • node: a divergent event- splitting of branches
  • leaf: end of branch, shows taxa or species
    > sister taxa = grouped together, closely related species
  • clade: a common ancestor and its descendents, particular group in a tree
50
Q

types of phylogenetic trees

A
  • phylogram: contains a scale of time
  • cladogram: doesn’t have a scale
51
Q

shared characteristics of primates

A
  • forward facing eyes
  • opposable thumbs
  • flat fingernails & sensitive fingertips
  • sexual dimorphism
  • form complex social groups
  • mammary glands
52
Q

important groups of primates

A
  • monkeys
  • hominoids
    > gibbons
    > hominids
    –> great apes
    > hominins (humans and other homos)
53
Q

trends in human evolution

A

Australopithecus –> H.habilis–> … H.neanderthalensis–> H.sapien
trends include:
- larger cranial capacity (brain size) over time
> increased skull volume = greater intelligence
- limb structure
> longer legs in proportion to arms, due to bipedalism
> locking knees
> greater angle at femur & shin bones join at an angle to support centre of mass & bipedalism
> pelvis has gotten smaller and flatter

54
Q

classification of humans

A

kingdom: animalia
phylum: chordata
class: mammalia
order: primates
family: hominidae
Genus: Homo (capitalised)
species: sapiens
“King Phylum Can Only Find Green Socks”

55
Q

multiregional theory

A

-all spontaneously mutated into homo sapiens (unlikely)

56
Q

out of Africa theory

A

~300,000 years ago, homo sapiens arose in Africa
- attempted to leave after 150,000 years
- successfully migrated out of Africa (~70,000 years) and colonised rest of world
-more likely theory

57
Q

how is the out of Africa theory supported by mtDNA

A
  • there is more genetic diversity between people in Africa compared to other people in the world ( more diversity in people in Africa than comparing someone from Australia and Sweden etc)
    -(founder effect)- little part of pop left africa , not representative of african population/pool (low genetic diversity),
  • few mutations/mutates predictably, so it can be used to track lineage
  • no recombination
    -errors aren’t repaired
58
Q

interpreting the fossil record

A
  • can be difficult as it is incomplete and is often revised with new discoveries
  • discovery of new species such as H. florensis fossils and denisovans bones found challenge previously held hypotheses of fossil record
59
Q

evidence for interbreeding between homo sapiens and homo neanderthalensis

A
  • evidence that H.sapiens and H.neanderthalensis interbred and produced fertile offspring
    > this is because all humans except those from africa have some neandethal DNA
  • however they are seperate species according to paleontology.
60
Q

evidence of new putative homo species

A
61
Q

migration of aboriginal and torres strait islander

A

~ 65,000 ya H.sapiens arrived via land bridge
-came from asia
- split from population in Papua New Guinea/Indonesia
-took ~9000 years to spread across Australia
-fossil evidence may be hard to obtain as its seen as potentially disrespectful to use ancestral remains

62
Q

connection to country and place (from bens notes)

A
  • due to the long occupation of australia by the indigenous pop the community has a strong connection to land
  • their connection to country involves a reciporical relo in which people sustain and manage the land through culture, ceremonies and care the land provides them

Bio 3/4 (4 decks)

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