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Biology > Pack 12 > Flashcards

Pack 12 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Define the genotype of an organism.

A

All the alleles that an organism has.

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2
Q

What does the genotype of an organism determine?

A

The limits within which the characteristics of an individual.

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3
Q

Other than the genotype of an organism what else can effect characteristics of an individual?

A

The environment - e.g. diet

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4
Q

Define phenotype. What is it the result of?

A
  • The observable or biochemical characteristics of an organism.
  • Result of the interaction between the expression of the genotype and the environment.
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5
Q

What is a gene what does it code for?

A

A length of DNA nucleotide bases. Usually codes for a polypeptide.

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6
Q

What is the name for the different forms of genes?

A

alleles

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7
Q

What is the position of a gene on a particular DNA molecule known as?

A

Locus

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8
Q

How many alleles can occur at the locus of any one chromosome?

A

1

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9
Q

How many gene loci are there for each gene in diploid organisms? Therefore how many alleles can each organism have of each gene?

A

2 - 2

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10
Q

What is the organism the allele on each chromosome is the same?

A

Homozygous

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11
Q

What is the organism the allele on each chromosome is the different?

A

Heterozygous

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12
Q

What is the allele of the heterozygote that expresses itself in the phenotype called?

A

Dominant

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13
Q

What is the allele of the heterozygote that does not express itself in the phenotype called?

A

Recessive

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14
Q

What is a homozygous organism with two dominant alleles called?

A

Homozygous dominant

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15
Q

What is a homozygous organism with two recessive alleles called?

A

Homozygous recessive

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16
Q

When Is the effect of a recessive allele apparent in the phenotype of a diploid organism?

A

When it occurs in the presence of another identical allele - homozygous recessive.

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17
Q

What are codominant alleles?

A

Two alleles both are expressed in the phenotype when they are different.

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18
Q

What is the organism referred to when a gene has more than two allelic forms.

A

Has multiple alleles for that character.

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19
Q

When representing a character why do you use uppercase for dominant and lower case for recessive and not two different letters?

A

Two different letters implies codominance.

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20
Q

What should you write when showing a cross before drawing a punnet square? (3)

A

The parents genotypes and phenotypes. Draw the gametes produced.

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21
Q

When a pure bred green (GG) plant is crossed with a pure bred yellow (gg) what are the offspring called? What is their genotype and phenotype?

A

First filial generation F1 generation. Gg - Green

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22
Q

When the F1 generation is crossed? What are the offspring called and what ratio are they in?

A

F2 generation. Green:yellow - 3:1

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23
Q

How many alleles of each gene can be present in a single gamete?

A

1

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24
Q

How should a ratio be written in biology?

A

X:1

25
Q

Why are Mendel’s results not exactly 3:1 in the F2 generation?

A

Statistical error - chance.

26
Q

What makes the results of a genetic cross experiment more representative?

A

Larger sample size.

27
Q

What is dihybrid inheritance?

A

How two characters determined by two different genes located on different chromosomes are inherited.

28
Q

For dihybrid inheritance where must the two genes be located.

A

On two different chromosomes.

29
Q

R=Round seeds r = wrinkled seeds
G=yellow g=green

Consider the cross of a pure bred round yellow seed plant and a wrinkled green seed plant.

What are the parental genotypes?
What gametes are produced by each plant?

A
  • RRGG; rrgg

- RG; rg

30
Q

R=Round seeds r = wrinkled seeds
G=yellow g=green

Consider the cross of a pure bred round yellow seed plant and a wrinkled green seed plant.

What are the phenotypes and genotypes of the F1 generation?

A

RrGg - Round Yellow

31
Q

R=Round seeds r = wrinkled seeds
G=yellow g=green

Consider the cross of a pure bred round yellow seed plant and a wrinkled green seed plant.

What gametes does the F1 generation produce?

A

RG, Rg, rG, rg

32
Q

R=Round seeds r = wrinkled seeds
G=yellow g=green

Consider the cross of a pure bred round yellow seed plant and a wrinkled green seed plant.

Give the ratio of the phenotypes produced.

A

Round wrinkled: round green: wrinkled yellow: wrinkled green.

9:3:3:1

33
Q

What is the law of independent assortment?

A

Each member of a pari of alleles may combine randomly with either of another pair.

34
Q

How are codominant alleles written. Example coat colour for cows Red and white colours.

A

C^W/C^R - superscript

35
Q

In cows alleles for red and white coat pigment are codominant. If a cow has both alleles the coat is roan.

What is the genotype and phenotype of:

a) a cross between two roan cows
b) a cross between a red and a white cow

A

a) - RR:RW:WW - Red:Roan:White
- 1:2:1
b) RW - roan

36
Q

In cows alleles for red and white coat pigment are codominant. If a cow has both alleles the coat is roan.

What colour coat does a heterozygous individual have?

A

Roan

37
Q

The gene I for immunoglobulin (ABO blood type) has three alleles. What is this called?

A

Multiple alleles.

38
Q

What are the three alleles for ABO blood type? Which are dominant to which?

A

A, B, O (Should be I superscript)

A and B are codominant, O is recessive.

39
Q

What are the ratios of phenotypes and genotypes of a cross between someone blood group O and AB?

A

AO (A): BO (B)

1:1

40
Q

What are the ratios of phenotypes and genotypes of a cross between someone blood group A (AO- heterozygous) and group B (BO - heterozygous)?

A

AB: BO (B): AO (A): OO (O)
1:1:1:1

41
Q

In what way are all females gametes the same? And in what way are males gametes different.

A

All female gametes contain the X chromosome. Half of male gametes contain an X chromosomes and the other half contain the Y chromosome.

42
Q

What is any gene carried on either the X or Y chromosome known as?

A

Sex linked.

43
Q

What is different about the X and Y chromosomes compared to the 22 other homologous pairs?

A

The X chromosome is much linger than the Y chromosome.

44
Q

What is the result of the fact that the Y chromosome is shorter than the X in terms of the expression of alleles?

A

For much of the length of the X chromosome there is no equivalent homologous portion on the Y chromosome.

Characteristics controlled by recessive alleles on this non-homologous portion of the X chromosome, therefore, will appear more frequently in males.

45
Q

What is an X linked genetic disorder?

A

A disorder caused by a defective gene on the X chromosome.

46
Q 
H = allele for blood clotting
h = defective

Give the ratio of phenotypes and genotypes of the cross between a carrier female (Hh) and a normal male (X^H Y).

A

Females - HH:Hh - normal:carrier - 1:1
Males - H:h - normal:haemophiliac - 1:1

*X superscript should be used

47
Q

Why do males always inherit haemophilia from their mother?

A

The defective gene is carried on the X chromosomes. Males inherit their X chromosome from their mother and their Y from their father.

48
Q

What is the genotype of a female ‘carrier’ of haemophilia?

A

X^H X^h

49
Q

What are two genes that occur on the same chromosomes called?

A

Linked

50
Q

What is an autosome?

A

A chromosome that is not a sex chromosome.

51
Q

Define autosomal linkage?

A

Two or more genes are carried on the same autosome.

52
Q

Assuming no crossing over, why is autosomal linkage significant in terms of inheritance?

A

All the linked genes remain together during meiosis and so pass into gametes together.

53
Q

If two genes are linked in a heterozygous individual (both dominant alleles are on the same homologous pair) what are the possible gametes produced? use A and B

A

AB or ab

54
Q

Two autosomal linked genes are:

G/g and N/n

Two individuals that are heterozygous for both (dominant allele on the same chromosomes) are crossed.

Assuming no crossing over give the offspring genotypes and the ratio of the phenotypes.

A

GGNN, 2x GgNn, ggnn

3:1 - dominant for both:recessive for both

55
Q

Explain why the actual ratio of offspring of two autosomal linked genes may not be 3:1?

A

Crossing over.

56
Q

Explain why the actual ratio of offspring after a genetic experiment may not be the same as the expected ratio. (3)

A

Small sample size; fertilisation of gametes is random; offspring ratios are a probability not fixed - arise by chance.

57
Q

Define epistasis.

A

Where the allele of one gene affects or masks the expression of another.

58
Q

In mice gene A controls distribution of black pigment.
A- produces agouti aa produces black.

Gene B: B- leads to the production of melanin.
bb leads to on pigment (albino).

Give the ratio o phenotypes and genotypes of a cross between two agouti mice (AaBb)
Explain the results.

A

AABB AABb AaBB AaBb
AaBb Aabb AaBb Aabb
AaBb AbBb aaBB aaBb
AaBb Aabb aaBb aabb

9:4:3 agouti to white to black

Same as dihybrid except the “1” or the “albino and black” is just albino because it masks the black allele.

Biology (18 decks)

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