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A Level Biology > Genetics (Topic 7A) > Flashcards

Genetics (Topic 7A) Flashcards

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1
Q

a gene is…

A

a section of DNA that is a sequence of nucleotide bases and determines a single characteristic

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2
Q

multiple alleles are…

A

if more than two alleles for each gene are present in the gene pool

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3
Q

co dominant is when…

A

both alleles contribute to the phenotype

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4
Q

modification is…

A

any change to the phenotype. it is not inherited by the future generation

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5
Q

alleles are…

A

different forms of the same gene

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6
Q

phenotype is…

A

the physical and observable characteristics of an organism that is determined by an organisms alleles and environment

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7
Q

recessive alleles need to be inherited from _____ _____ to be expressed in the _____

A

both parents
phenotype

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8
Q

homozygous dominant is…

A

an organism that has inherited two dominant alleles

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9
Q

homozygous recessive is…

A

an organism that has inherited to two recessive alleles

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10
Q

heterozygous is when…

A

an organism that has inherited one dominant and one recessive allele

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11
Q

a mutation is…

A

any change to the genotype caused by change in DNA and can be inherited

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12
Q

genotype is…

A

the genetic makeup of an organism

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13
Q

dominant alleles only….

A

need to inherit one from parents to be expressed in phenotype

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14
Q

incomplete dominance is when…

A

neither allele is dominant, both are equally giving an intermediate

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15
Q

what are the three blood groups?

A

A, B and O

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16
Q

which blood groups are dominant?

A

A and B

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17
Q

which blood group is recessive?

A

O

18
Q

sex linkage occurs when…

A

the genes for a certain characteristic are carried on the sex chromosome

19
Q

which chromosome is longer X or Y?

A

X

20
Q

chromosome __ is longer than __ so it ______more alleles

A

X
Y
carries

21
Q

red green colour blindness is caused by a _____ allele

A

recessive

22
Q

males only inherit __ allele from their ______

A

1
mother

23
Q

are men colourblind if they inherit one allele for colour blindness

A

yes

24
Q

is colour blindness more prevalent in men or women?

A

men

25
Q

dihybrid crosses investigate….

A

the inheritance of two characteristics

26
Q

epistasis is when…

A

the allele of one gene affects or masks the expression of another in a phenotype

27
Q

autosomal linkage is…

A

when two or more genes are located on the same chromosome

28
Q

autosomal linked genes are more…

A

likely to be inherited together

29
Q

the ____ of the loci of the _ genes on the chromosomes the ____ the chance of recombination forming

A

closer
2
lower

30
Q

recombinants are…

A

new combinations of phenotypes that prove linkage is not complete

31
Q

how are recombinants produced?

A

crossing over of chromatids

32
Q

the chi squared test is used to…

A

test if the observed frequency matches the expected frequency

33
Q

the null hypothesis states that

A

there is no statistically significant difference between the observed frequency and the expected frequency

34
Q

if the value for x^2 exceeds the critical value then…

A

you reject the null hypothesis

35
Q

degrees of freedom =

A

no. of categories - 1

36
Q

what does 2pq stand for in the hardy-weinberg principle?

A

heterozygous

37
Q

the specific point of a gene on the chromosome is called the…

A

locus

38
Q

the gene pool is…

A

all of the alleles present in a population

39
Q

Why are males more likely to inherit a sex linked recessive condition than females?
2 marks

A
  1. males only need to inherit one allele to have the characteristic
  2. whereas, females need two recessive alleles
40
Q

A grey body long winged fly is crossed with a black bodied short winged fly. Explain these results:
Grey B + long W - 223
Black B + short W - 218
2 marks

A
  1. The genes for colour and wing length are linked
  2. There is no crossing over

A Level Biology (19 decks)

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