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BIOLOGY PAPER 2 > PATTERNS OF INHERITANCE > Flashcards

PATTERNS OF INHERITANCE Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

phenotypic variation

A

differences between the phenotypes of a group of organisms

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2
Q

environmental factors affecting phenotypic variation in animals & plants

A
  • diet in animals affects body mass
  • etiolation in plants due to lack of light (grow long and spindly to reach light source)
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3
Q

genetic factors affecting phenotypic variation in plants & animals

A
  • genes affecting body mass
  • chlorosis where plant doesn’t produce enough chlorophyll due to iron deficiency
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4
Q

how does sexual reproduction lead to genetic variation?

A
  • crossing over in prophase 1
  • independent assortment in metaphase 1 due to random distribution and segregation of homologous chromosomes
  • independent assortment in metaphase 2 due to random distribution and segregation of sister chromatids
  • random fertilisation
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5
Q

what do monogenic inheritance diagrams show?

A

inheritance of alleles of a single gene

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6
Q

what is the F1 outcome for monogenic inheritance?

A

100%

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7
Q

what do dihybrid crosses show?

A

the inheritance of 2 separate genes on different chromosomes eg pea colour & shape

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8
Q

in a heterozygous dihybrid cross what will the ratio be?

A

9:3:3:1

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9
Q

what are multiple alleles?

A

genes with more than 2 alleles eg IA and IB for blood group

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10
Q

what is codominance?

A

both alleles equally dominant so both expressed in phenotype

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11
Q

what is sex linkage?

A

traits inherited by 1 biological sex
- determined by non homologous (only present on X) region of X
- tops of Y chromosomes lost in evolution so it has less genes

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12
Q

what is linkage?

A

genes for different characteristics are found at different loci on the same chromosome
- inherited together

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13
Q

what is epistasis?

A
  • genes at 1 locus interact with genes at another
  • by masking or suppressing their expression
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14
Q

what is autosomal linkage?

A
  • 2 genes on same chromosome
  • inherited together
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15
Q

what is the ratio for recessive epistasis?

A

9:7 or 9:3:4

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16
Q

what is the ratio for dominant epistasis?

A

12:3:1 or 13:3

17
Q

what is the ratio for reciprocal epistasis?

A

15:1

18
Q

what is the purpose of a chi squared test?

A

assesses whether results are different from expected due to chance or another factor

19
Q

when does a chi squared value show results are significant?

A

if the calculated value is greater than the critical value

20
Q

continuous variation

A
  • any value on a scale
  • caused by genes with many alleles
  • eg height
  • shown on histogram
21
Q

discontinuous variation

A
  • distinct categories
  • caused by genes with few alleles and the environment
  • eg blood group
  • shown on bar chart
22
Q

stabilising selection

A
  • eliminates extremes in a population
  • favours most normal/common
  • occurs with unchanging environmental conditions
23
Q

genetic drift

A
  • random change in allele frequency in a population
  • some alleles passed and some disappear
  • some phenotypes become common and others rare
24
Q

founder effect

A
  • loss of genetic variation
  • establishment of new population as a small number of individuals colonise a new area
25
Q

directional selection

A
  • favours individuals at the extreme
  • changes population characteristics
  • occurs due to environmental change
26
Q

genetic bottleneck

A
  • chance event
  • causes a dramatic reduction in the size of a population/gene pool
  • big effect on allele frequency
27
Q

speciation

A

evolution of a new species from an existing one

28
Q

sympatric speciation

A
  • reproductive mechanisms with no physical barrier
  • change in courting behaviour which is not recognised by the rest of the species
  • polyploidy (mutation affecting whole sets of chromosomes)
  • hybrid sterility (mating of 2 species)
29
Q

allopatric speciation

A
  • geographical isolation
  • 2 populations of same species separated
  • selection of diff alleles
  • mutations & diff selection pressures
  • gene pools become so different that they are reproductively isolated
30
Q

artificial selection

A
  • selective breeding of desired characteristics
  • repeated over generations
  • eg to increase milk or wheat yield
  • important to maintain a resource of genetic material for use in selective breeding as growing conditions change
  • important to consider ethics surrounding extreme selective breeding
31
Q

under what assumptions is the hardy Weinberg principle used?

A
  • large population
  • mating in population is random
  • no mutations, genetic drift or migration
  • no selective advantages
32
Q

what does p represent in the HW equation?

A

frequency of dominant allele

33
Q

what does q represent in the HW equation?

A

frequency of recessive allele

34
Q

what does pq represent in the HW equation?

A

frequency of heterozygotes

BIOLOGY PAPER 2 (8 decks)

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