Inheritance

Question 1

Genotype

Answer 1

The genetic constiution of an organism.

Question 2

Phenotype

Answer 2

The expression of an organim’s genetic constitution, combined with its interaction with the enviroment.

Question 3

Allele

Answer 3

Different forms of a particular gene found at the same locus (position) on a chromosome. A single gene could have many alleles.

Question 4

How many alleles per gen do diploid organims carry?

Answer 4

2

Question 5

What is meant by a dominant allele?

Answer 5

An allele whose characteristic will always appear in the phenotype, whether one or two are present.

Question 6

What is it meant by a recessive allele?

Answer 6

An allele whos characteristic only appears in the phenotype if no dominant allele is present, meaning two must be present.

Question 7

What is meant by a codominant allele?

Answer 7

Two dominant alleles that both contribute to the phenotype, either by showing a blend of both characteristics, or the characteristics appearing together.

Question 8

What is meant by homozygous and heterozygous?

Answer 8

Homozygous = both allelles are domoninant or both alleles are recessive.

Heterozygous = one allele is dominant the other is recessive

Question 9

Monohybrid inheritance

Answer 9

Where one phenotypic characterstic is controlled by a single gene.

Question 10

Draw a Punnet square to show a monohybrid cross with parental genotypes of GG and gg.

What % of these offspring will express the characteristic determined by allele G?

Answer 10

Check Physics maths tutor flashcard.

Q2. 100%

Question 11

Draw a Punnet square to show a monohybrid cross with parental genotypes of Gg and Gg.

What % of these offspring should express the characterstic determined by allele G?

Answer 11

Check PM flahcards

Q2. 75%

Question 12

Draw an example of a genetic diagram

Answer 12

Check PM Flashcard

Make sure to include:
Parent phenotypes
Parental genotypes
Gametes
Offspring genotype (punnet square)
Offspring phenotype = ratio

Question 13

Define dihybrid inheritance

Answer 13

Where two phenotypic characteristics are dtermined by 2 different genes present on 2 different chromosomes at the same time.

Question 14

Draw a Punnet square to show a dihybrid cross with parental genotypes of RrGg and RrGg.

How many of these offspring should have the same phenotype as their parents

Answer 14

Refer to PM flashcard

Q2. 9/16
6 will math their parents on one characteristics, but differ on the other
1 will differ on both characteristics

Question 15

What is meant by sex-linkage

Answer 15

Where an allele is located on ne of the sex chromomsomes, meaning its expression depends on the sex of the individual

Question 16

Why are male more likely to express a recessive sex-linked allele?

Answer 16

Most sex-linked alleles are located on the X chromosome. There males only get one copy of the allele, so will express this characterstic even if its recessive. Since female get 2 alleles, this is less likely.

Question 17

Which parent do males inherit sex-linked characteristics from?

Answer 17

Their mother, since the Y chromosome can only come from their father. Therefore the mother is heterozygous for sex-linked alleles, she is a carrier and may pass on the trait on.

Question 18

Draw a punnet square to show a sex-linked cross with parental genotypes of Xᴴ Xʰ and XᴴY

Describe the four possible phenotypes of these offspring

Answer 18

Refer to PM flashcard

Q2. Normal female, carrier female, normal male, affected male

Question 19

What is it meant by autosomal linkage?

Answer 19

Where two or more genes are located on the same (non-sex) chromosome. In this case, only one homologous pair is needed for all four alleles to be present. For genes that arent linked, two homologous parents are needed.

Question 20

Draw a Punnet square to show a multiple alleles cross with parental genotypes of IᴬIᴼ and IᴮIᴼ.

Answer 20

Refer to PM flashcard

Question 21

If Iᴬ and Iᴮ are codomoninant and Iᴼ is recessive, which alleles could the offspring express?

Answer 21

AB, A, B, O

Question 22

What is meant by epistasis?

Answer 22

Where two non-linked genes interact, with one gene either masking or supressing the other gene

Question 23

What are the two types of epistasis?

Answer 23

Recessive epistasis = where two homozygous recessive alleles mask expression of another allele.

Dominant epistasis = where one dominant allele masks expression of multiple other alleles.

Question 24

Draw a Punnent square to show an epistsis cross with parental genotype of AABB and aabb.

Genotypes BB or Bb allow expression of gene A, while genotype bb masks gene A. With this in mind, what % of the offspring will have gene A masked>

Answer 24

25%

Question 25

What is the chi-squared test.

Answer 25

A stastical test to finf out whethet the difference between observed and expected data due to chance or real effect.

Question 26

What are the 4 criterias of the chi-squared test?

Answer 26

• Data placed in discrete categories
• Large sample size
• Only raw count data allowed i.e. not perecentages
• No data values equal 0

Question 27

How is a chi-squared test perfomed

Answer 27

• The formula results in a number, which is them compared to a critical value (for the corresponding degrees of freedom).
• If the number is greater than or equal to the critical value, we conclude there is a significant different between the observed and expected data an that the results did not occur due to chance.

Question 28

How can we use a chi-squared test in relation to the content of this topic?

Answer 28

We can compare expected phenotypic ratios with observed ratios to test our understanding of how different genes and alleles are inherited.