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Biology > Genetics, Biodiversity and Classification > Flashcards

Genetics, Biodiversity and Classification Flashcards

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1
Q

Species

A
  • similar DNA sequence
  • same ecological niche
  • can breed to produce fertile offspring
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2
Q

Genetic diversity

A

Total number of different alleles in a population

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3
Q

Genetic mutation

A

Random change in base sequence of DNA

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4
Q

Causes of genetic mutation

A
  • spontaneously during DNA replication
  • high energy radiation / ionising radiation
  • carcinogens
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5
Q

Describe impact of deletion of nucleotide from original DNA sequence

A

Alters reading frame of gene downstream of mutation - potential to change all triplets so affects formation of multiple amino acids

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6
Q

Chromosome mutation

A

Change to structure or number of chromosomes

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7
Q

Non-disjunction

A

Failure of homologous pairs/ sister chromatids to separate during meiosis so cells have fewer or more chromosomes after fertilisation

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8
Q

Polyploidy

A

More than one complete set of chromosomes

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9
Q

Homologous Pair

A

Pair of chromosomes - maternal and paternal

Same gene loci

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10
Q

Importance of meiosis

A
  • number of chromosomes halved so diploid number is restored at fertilisation
  • genetic variation from independent segregation and cross over
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11
Q

Cross over

A
  • homologous pairs come together in a bivalent and their chromatids becomes twisted forming a chiasma
  • equivalent LENGTHS OF non sister CHROMATIDS exchanged
  • new combinations of alleles
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12
Q

Independent Segregation

A
  • formation of random combinations of maternal and paternal chromosomes in a homologous pair during metaphase I (meiosis)
  • chromosomes of each homologous pair sort into gametes independently of another pair
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13
Q

Meiosis - Prophase

A

DNA condenses so chromosomes are visible
Nuclear envelope breaks down
Spindle fibres form
(1) cross over occurs

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14
Q

Meiosis - Metaphase

A

Spindle fibres attach to chromosomes and they align at equator

(1) in homologous pairs - independent segregation/crossover
(2) random alignment of sister chromatids

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15
Q

Meiosis - Anaphase

A

Spindle fibres contract and shorten

(1) one chromosome from each homologous pair migrates to opposite pole
(2) chromatids pulled apart

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16
Q

Meiosis - Telophase

A

Nuclear envelope reforms and chromosomes unravel

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17
Q

Importance of genetic diversity

A
  • species more likely to survive environmental change

- greater probability an individual posses allele which allows it to survive

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18
Q

What is evolution and what factors cause it to take place

A

Change in allele frequency over time

  • genetic variation
  • selection pressures
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19
Q

Natural Selection

A
  • genetic MUTATIONS create different alleles
  • SELECTION PRESSURE
  • certain alleles are advantageous
  • individuals with this allele more likely to survive and reproduce so have selective advantage
  • frequency of allele increases
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20
Q

Evidence for evolution

A
  • genetic code and ATP is universal

- all proteins formed from same 20 amino acids

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21
Q

Reasons for classifying organisms

A
  • easier to study
  • understand evolutionary relationships
  • keep track of changes
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22
Q

Artificial classification and its benefits/drawbacks

A

Grouping organisms based on FREQUENCY of similar observable characteristics (phenotype)

  • stable classification
  • simplified method of grouping individuals
  • individually are usually not phylogenetically related since phenotype affected by environment
  • provides limited information (cannot sort into species etc.)
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23
Q

Phylogenetic Classification

A

Grouping organisms based on evolutionary relationships where shared features are derived from a common ancestor

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24
Q

Evidence of phylogenetic classification

A
  • common ancestors
  • proportion of similar DNA since mutations occur over time
  • comparison of amino acid sequences in cytochrome C (found in all eukaryotes)
  • immunological comparisons of proteins using antibodies
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25
Q

Suggest why amino acid sequence of two closely related organisms is the same but they have a different genetic code

A

Genetic code is degenerate so may have a different base sequence which codes for all the same amino acids

26
Q

Hierarchy

A
  • groups contained within larger composite groups

- no over lap

27
Q

Linnaeus Classification

A

Domain, Kingdoms, Phylum, Class, Order, Family, Genus, Species

Dumb kids playing catch on freeways get smashed

28
Q

Courtship

A

Members of the same species use the same sequence of behaviours to communicate with mates

29
Q

Suggest how courtship leads to successful reproduction

A
  • recognise members of their own species and of opposite sex
  • identify mate capable of breeding to ensure synchronised mating
30
Q

Suggest how courtship is important in the survival of offspring

A
  • form a pair bond so both parents raise offspring to maximise chances of survival
  • female can choose a strong and healthy mate which improves survival chances of offspring as advantageous alleles are passed on
31
Q

Biodiversity

A

Number and variety of living organisms in an area

32
Q

Factors to consider when investigating biodiversity

A
  • species richness
  • genetic diversity
  • ecosystem diversity (range of habitats)
33
Q

Species Diversity

A
  • species evenness

- species richness

34
Q

Suggest why species diversity in a desert is low

A

Only a few species have necessary adaptations to survive harsh conditions

35
Q

Community

A

All living organisms in an ecosystem at a given time

36
Q

Ecosystem

A

All living and non living components of an area

37
Q

Ecological niche

A

Role of an organism in its environment

38
Q

Habitat

A

Physical environment where an organisms lives

39
Q

Species richness

A

Number of different species only

40
Q

Suggest how farming reduces species diversity

A
  • undesirable species are outcompeted by farmed species in terms of space and resources
  • pesticides
  • eutrophication due to fertilisers
41
Q

Deforestation

A

Action of removing a wide area of trees

42
Q

Causes of deforestation

A
  • Agricultural farming
  • Livestock farming
  • Over population so infrastructure expansion
  • Logging
43
Q

Solutions to low species diversity

A
  • hedgerows rather than fences
  • biological control instead of pesticides
  • organic fertilisers
  • crop rotation
44
Q

Explain what is meant by a stabilising selection and describe the circumstances under which it takes place

A
  • occurs in an unchanging environment
  • individuals with phenotype closest to the mean are best adapted
  • selection against extremes
  • mean is unaltered
  • range of phenotypes is reduced
  • increasing proportion of population well adapted to environment
45
Q

Explain what is meant by directional selection

A
  • environmental change
  • extreme phenotype is favored over other phenotypes so more likely to survive and reproduce
  • whole distribution shifts over time in the direction of the favoured phenotype
46
Q

Speciation

A

Formation of a new and distinct species

47
Q

Describe how speciation occurs

A
  • individuals of same species are isolated
  • have their own unique selection pressures
  • acquire different allele frequencies over time
  • genes become so different they can no longer breed to produce fertile offspring
48
Q

Explain factors which give rise to variation which results in different phenotypes

A
  • different environments with different selection pressures
  • mutations to genetic code
  • crossover and independent segregation during meiosis
  • random nature of sexual reproduction
49
Q

Suggest why gene technologies are now used to classify organisms over traditional methods

A
  • more accurate

- easier to carry out

50
Q

Normal Distribution

A

Distribution of random variables represented by a symmetrical bell-shaped curve

51
Q

What is meant by closely related in terms of evolution

A

Close common ancestor

52
Q

When does cross over occur

A

Between prophase 1 and metaphase 1

53
Q

Suggest why individuals may have similar observable characteristics even though they are different species

A
  • could be closely related instead
  • could have evolved in same environment
  • characteristics could be polygenetic
54
Q

Under what environmental conditions does directional selection occur

A

Slow changing environment in one direction

55
Q

Describe how immunological comparisons between species are made

A
  • protein from blood serum of test 1 species is extracted
  • injected into another species so antigens produce an immune response
  • blood serum extracted from injected species containing antibodies
  • added to blood serum of test 2 species containing same protein to be tested
  • level of precipitation determines how closely related both test species are
56
Q

State comparisons of genetic diversity that scientists use in order to generate classifications for organisms

A
  • base sequence of DNA
  • base sequence of mRNA
  • amino acid sequence of common proteins
57
Q

Suggest why population of animals has low genetic diversity

A
  • hunting
  • small population due to genetic bottle neck (sharp reduction in population size due to natural disaster)
  • founder effect (descended from a small number of ancestors)
58
Q

Explain how hunting reduces genetic diversity

A
  • reduced population size
  • founder effect
  • inbreeding
59
Q

Explain why small population means low genetic diversity

A
  • only a few copies of genes passed on

- not all alleles of genes included

60
Q

Explain why an area has higher biodiversity

A
  • greater variety of habitats
  • greater variety of food sources
  • more niches
  • more plant species
  • more animal species
61
Q

How to calculate number of genetically distinct cells produced from independent segregation given chromosome number

A

2^chromosome number

Option to 2 cells and 8 to choose from

62
Q

Justify whether two organisms are same species / part of same hierarchical group

A
  • recent divergence
  • same branch in phylogenic tree
  • recent divergence means share close common ancestor or similar bas sequence
  • phylogeny based on classification
  • shared anatomy
  • old classification based on anatomy but new biochemical data more accurate
  • scientific knowledge develops over time

Biology (14 decks)

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