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AQA A level Biology > Inheritance > Flashcards

Inheritance Flashcards

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1
Q

What experiment did Mendel do

A

Pea plant experiment

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2
Q

What is the term to describe an organism that has the same alleles

A

Homozygous

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3
Q

From Mendel’s experiment, what number generation are the homozygous individuals in

A

F zero generation

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4
Q

From Mendel’s experiment, what is the number generation where all the individuals present the dominant gene

A

F 1 generation

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5
Q

What generation, from Mendel’s experiment have individuals that both present dominant and recessive genes

A

F 2 generation

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6
Q

When you mix 2 homozygote indiviudals (2 F zero individuals), what generation is the offspring

A

F one generation

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7
Q

If you mix 2 heterozygote individuals, what generation is the offspring

A

F 2 generation

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8
Q

What is the offspring if you mix a heterozygote and a homozygote

A

A non-Mendelian ratio

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9
Q

Define genotype

A

The genetic makeup of an individual / the alleles of a gene, or all of the alleles of all the genes that an individual inherits

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10
Q

Define phenotype

A

The expression of the genotypes and its interaction with the environment

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11
Q

Define dominant allele

A

The allele that is always expressed in phenotype when present

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12
Q

Define codominant allele

A

Both alleles are expressed in the phenotype when present

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13
Q

Define recessive allele

A

The allele that is only expressed in the phenotype only in the absence of a dominant allele

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14
Q

Define heterozygous

A

Possessing different alleles of genes at the same locus on homologous chromosomes

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15
Q

Define homozygous

A

Possessing the same alleles of genes at the same locus on homologous chromosomes

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16
Q

When writing letters for the genotype, what letter comes first

A

The capital letter

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17
Q

What is the ratio for monohybrid inheritance

A

3:1 (dominant: recessive)

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18
Q

What is the other name for the test cross

A

back cross

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19
Q

How is the test cross/ back cross carried out

A
  • Cross dominant phenotype with a recessive phenotype
  • Look at offspring
  • If any offspring show recessive phenotype the dominant characteristic must be heterozygous
    -If no offspring show recessive phenotype then you can’t tell
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20
Q

If the chi squared value is less than the critical value (@p=0.05), is the difference between the observed and expected significant and is the null hypothesis accepted or rejected

A

Not significant therefore is due to chance alone so accept null hypothesis

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21
Q

If the chi squared value is greater than the critical value @ p=0.05, is the difference between the observed and expected significant and is the null hypothesis accepted or rejected

A

Is significant and therefore not due to chance alone so reject null hypothesis

22
Q

How do you calculate the expected value, for chi squared

A

(sum of observed x phenotype ratio) / sum of ratios

23
Q

How do you calculate the degrees of freedom (DoF), for chi squared

A

number of categories (phenotypes) - 1

24
Q

What are codominant alleles

A

Where both alleles are equally dominant and both are expressed when they are present

25
Q

When writing codominant alleles into punnet squares, how do you write it

A

Write a gene letter, then write the colour etc, (the allele letter), like a power e.g. C^W

26
Q

What is the co-dominant inheritance ratio

A

1:2:1

27
Q

What is the other name for the sex chromosomes

A

Heterosomes

28
Q

AQA defines any gene in this particular region to be a sex-linked gene, what is the name of the region

A

Non-homologous regions

29
Q

What is the only chromosome that contains a non-homologous region

A

the X chromosome

30
Q

Which chromosome is larger, the X or the Y

A

X

31
Q

Who are more likely to have a sex-linked disease, males or females, and why

A

Males since they only need one recessive allele since they only have one X chromosome, wherease females have 2 X chromosomes so need 2 recessive alleles in order to have the disease

32
Q

When writing the phenotype of sex-linked alleles, what must you include

A

The sex, female or male

33
Q

When writing the genotype of a sex-linked male, what is not included and why

A

Whether the chromosomes are homozygous or heterozygous since only the X chromosome carries the alleles

34
Q

When asked what evidence is there that this disorder is recessive from a pedigree diagram, what is the answer that you must look for in the diagram

A

Where an affected offspring is produced from 2 non-affected parents

35
Q

When asked what evidence is there that this disorder is NOT sex linked from a pedigree diagram, what is the answer

A

Look for an affect daughter from a non-affected father

36
Q

What is meant by the term autosomal recessive trait

A

Non sex chromosomes, won’t be expressed if the dominant allele is present

37
Q

In a pedigree diagram what is the evidence that the disorder is sex linked

A

Only males have the disorder

38
Q

What is the dihybrid inheritance ratio

A

9:3:3:1

39
Q

What is autosomal linkage

A

The name given to the situation where 2 or more genes are carried on the same autosome

40
Q

What are autosomes

A

Chromosomes other than sex chromosomes

41
Q

In an homologous pair of autosomal linkage, how many alleles are accommodated

A

4

42
Q

How many gametes can be produced from 1 homologous pair of linked chromosomes

A

2

43
Q

In autosomal linkage, are most of the offspring the same or different from the parents

A

The same

44
Q

Why in autosomal linkage, are the offspring likely to be the same as the parent

A

Since there are few recombinant offspring since recombinant offspring only occur if crossing over occurs

45
Q

What causes recombinant offspring in autosomal linkage

A

Crossing over

46
Q

When 2 F1 linked parents cross, how do the chromosomes act

A

As one

47
Q

How does the degree of linkage in chromosomes vary

A

Depending on how close the genes are on chromosomes

48
Q

If a chromosome is really linked, is it more likely to behave as one or two

A

one

49
Q

When the chromosome is less linked, the liklihood of what increases

A

Likelihood of crossing over increases

50
Q

Why is the likelihood of crossing over increased when the chromosomes are less linked

A

Since there is more space between the genes on the chromosomes, so a larger chiasma

51
Q

What is epistasis

A

The interaction between two non-linked genes which causes one gene to mask the expression of the other in the phenotype

AQA A level Biology (33 decks)

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