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bio component 2 > variation, evolution and classification > Flashcards

variation, evolution and classification Flashcards

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Biology 101 flashcards
1
Q

describe continuous variation

A
  • controlled by multiple genes
  • characteristic shows graduation from one extreme to another
  • normally distributed
  • influenced by environment
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2
Q

describe discontinuous variation

A
  • controlled by a singe gene
  • grouped into categories (e.g blood group)
  • no intermediates
  • environment has little influence
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3
Q

what is heritable variation?

A
  • variation that results from genetic factors due to sexual reproduction
  • i.e crossing over in prophase I, independent assortment in metaphase I/II, random fertilisation
  • establishes new allele combinations
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4
Q

what is non-heritable variation?

A
  • phenotypic variation due to environmental factors
  • i.e diet, exercise (animals), temp, light, ions present (plants)
  • organisms can have identical genotypes and still display variety
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5
Q

what is meant by the term ‘selection pressure?’

A

an environmental factor that cause changes in allele frequency in a population

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6
Q

give examples of selection pressures (same as selective agents)

A
  • inter/intraspecific competition
  • humans
  • environment
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7
Q

what is meant by the term ‘gene pool’?

A

the total of all the alleles for all the genes in a population

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8
Q

what is meant by the term ‘allele frequency’?

A

the proportion of alleles of a gene in a gene pool

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9
Q

explain the process of natural selection

A
  • random mutations cause variation in a population
  • some individuals now have a selective advantage
  • those individuals survive and reproduce, passing on their advantageous alleles
  • this is repeated over many generations
  • leads to changes in allele frequency
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10
Q

what are the conditions for the Hardy-Weinberg principle?

A
  • large population
  • random mating
  • no migration (population is isolated)
  • no selection for/against any phenotype
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11
Q

what is the HW principle used for?

A
  • to measure allele frequency and from these predict genotype frequencies
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12
Q

what is meant by the term ‘species’?

A

a group of similar organisms that can interbreed to produce fertile offspring

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13
Q

what is genetic drift?

A

a random small change in a allele frequency (as a result of e.g not all individuals reproducing)

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14
Q

what is the founder effect?

A
  • when a small sample of individuals in a population are isolated to form a new colony
  • this sample is not representative of gene pool
  • leads to genetic drift within this small population and may cause increase in frequency of rare alleles
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15
Q

what is meant by the term ‘isolation mechanisms’?

A

features that prevent breeding between species

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16
Q

what is allopatric speciation?

A
  • when 2 groups within a population are separated by a geographical barrier
  • physically prevented from breeding with each other
  • each group adapts to new environment
  • undergo natural selection
17
Q

what is sympatric speciation?

A
  • there is no geographical barrier between groups
  • have other isolating mechanisms (e.g breeding at different times of year, different mating behaviours, morphological differences- different shaped genitals, hybrid sterility- hybrids have different no. of chromosomes so are infertile)
18
Q

what is taxonomy and what is meant by it being ‘dynamic’?

A
  • study of principles underlying classification
  • it is highly subjective due to differences of opinion about whether morphology or biochemical methods are more central for basis of classification
19
Q

what is the order of organisation?

A
  • Domain, Kingdom, Phyllus, Class, Order, Family, Genus, Species
20
Q

why does classification have a ‘tentative’ nature?

A

classification systems aren’t fixed as we gain more information

21
Q

what are the two methods that allow us to recognise closely related species?

A
  • morphology (organisation of living organisms into groups according to their shared physical structures or features)
  • biochemical methods (comparing certain molecules (e.g DNA/proteins) across species to see how similar the structures of them are)
22
Q

what is the advantage of using biochemical methods over morphology?

A

can reduce mistakes made due to convergent evolution

23
Q

what is an example of biochemical method and how does it work?

A
  • genetic fingerprinting
  • measures proportion of DNA or proteins shared between species
  • DNA/protein fragments are usually displayed as bands in electrophoresis gel
24
Q

what is a phylogenetic hierarchy?

A

a hierarchy (large group of items that is split into smaller and smaller groups) based on how closely organisms are related

25
Q

what is meant by the term ‘biodiversity’?

A

the number of species and number of individuals of each species in a given environment
- can be calculated using simpson’s diversity index

26
Q

what are homologous structures?

A

structures which share the same evolutionary origin but can have different functions

27
Q

what are analogous structures?

A

structures that can look similar and have the same function but have different origins

28
Q

explain how analysing amino acid sequences of proteins provides useful data for taxonomists

A
  • taxonomists look for similarities and differences in the protein structure
  • closely related species have similar a.a sequences
  • because DNA codes for the a.a sequence, we can conclude that closely related species have simlar DNA
  • mutations result in change DNA
  • leading to more differences in DNA and therefore a.a sequences
29
Q

how can biodiversity be assessed at a genetic level?

A
  • by looking at the variety of alleles in the gene pool of a population
  • look at proportion of polymorphic loci across the genome (polymorphism: the presence of several different types/forms of individuals among members of a single species)
  • biodiversity assessed by determining no. alleles at a locus OR proportion of population with a specific allele

bio component 2 (5 decks)

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