Inheritance

Question 1

Define diploid

Answer 1

An organism with a pair of homologous chromosomes, it has 2 alleles of each gene

Question 2

Define gene

Answer 2

A sequence of DNA that codes for a certain protein

Question 3

Define allele

Answer 3

A variation of a gene

Question 4

Define genotype

Answer 4

The combination of alleles that an organism has

Question 5

Define phenotype

Answer 5

The physical expression of the genotype and its interactions with the environment

Question 6

What is a dominant allele?

Answer 6

An allele always expressed in the phenotype

Question 7

What is a recessive allele?

Answer 7

An allele only expressed when it is homozygous

Question 8

What is a codominant allele?

Answer 8

When both alleles are expressed in the phenotype as an intermediate

Question 9

Define homozygous

Answer 9

Both alleles are the same

Question 10

Define heterozygous

Answer 10

Both alleles are different

Question 11

Define locus

Answer 11

The location/position of a gene on a chromosome, the alleles of a gene always have the same locus

Question 12

What is monohybrid inheritance?

Answer 12

Inheritance of a characteristic controlled by a single gene

Question 13

What will be the F2 Phenotypic ratio of a monohybrid inheritance from a homozygous dominant male and a homozygous recessive female?

Answer 13

3 : 1Dominant : Recessive

Question 14

What is dihybrid inheritance?

Answer 14

Inheritance of two characteristics that are controlled by separate genes

Question 15

What will be the F1 generation be in a dyhybrid cross between a homozygous dominant and a homozygous recessive?

Answer 15

100% heterozygous

Question 16

What will be the ratio of the F2 generation in a dyhybrid cross between a homozygous dominant and a homozygous recessive?

Answer 16

9 : 3 : 3 : 19 : Both dominant 3 : Dominant allele 1, recessive allele 23 : Dominant allele 2, recessive allele 11 : Both recessive

Question 17

What is codominance?

Answer 17

When there are multiple alleles that are dominant and can all be expressed in the phenotype as an intermediate

Question 18

What is an example of codominance?

Answer 18

Blood group

Question 19

What will be the F1 generation of a codominant cross between two different homozygous dominant patents

Answer 19

100% heterozygous

Question 20

What will be the F2 generation phenotypic ratio of a codominant cross between two different homozygous dominant patents

Answer 20

1 : 2 : 11 : Homozygous allele 11 : Homozygous allele 22: Heterozygous

Question 21

What is epistasis?

Answer 21

An interaction between genes where the expression of one gene suppresses the expression of another

Question 22

How would you refer to two genes showing epistasis

Answer 22

gene … is epistatic to gene …

Question 23

How does epistasis effect phenotypic ratios?

Answer 23

A dihybrid cross on epistatic genes will not result in the normal phenotypic ratio

Question 24

What is the phenotypic ratio of a dihybrid cross where the epistatic gene is recessive?

Answer 24

9 : 3 : 4

Question 25

What is the phenotypic ratio of a dihybrid cross where the epistatic gene is dominant?

Answer 25

12 : 3 : 1

Question 26

What is an autosome?

Answer 26

A non-sex chromosome

Question 27

How many autosomes do humans have?

Answer 27

44

Question 28

What is an autosomal linkage?

Answer 28

It is where two genes are found on the same autosome and are therefore inherited together

Question 29

What is autosomal linkage not affected by?

Answer 29

independent segregation

Question 30

Does autosomal linkage affect the phenotypic ratios from a dihybrid cross?

Answer 30

Yes, because linked genes are inherited together they behave more like a monohybrid cross

Question 31

What does an autosomal linkage mean for offspring?

Answer 31

They are more likely to have the same genotype and phenotype as their parents

Question 32

What can affect an autosomal link?

Answer 32

Crossing over, however this is dependent on the loci of the two genes. The closer to two are and the closer the autosomal link the less likely they are to be separated during crossing over but it is not impossible

Question 33

What will be the result of the phonotypes and genotypes of offspring after an inherited autosomal link, taking crossing over into account?

Answer 33

The majority of offspring will share their parents phenotypes and genotypes however a small percentage will not because of crossing over

Question 34

Where are homologous pairs found?

Answer 34

In diploid organisms

Question 35

What are homologous pairs?

Answer 35

Same gene but different allele

Question 36

What is a sex linkage?

Answer 36

The expression of alleles located on sex chromosomes depends on the sex of the individual

Question 37

What are the sex chromosomes of a female?

Answer 37

XX

Question 38

What are the sex chromosomes of a male?

Answer 38

XY

Question 39

What is different about the X and Y chromsomes?

Answer 39

- X chromosome is much bigger than Y- Y is missing many of the genes present on X

Question 40

What is typical of a sex linkage phenotypical ratio?

Answer 40

1 : 1Female carrier : Male sufferer