Inheritance

Question 1

define allele

Answer 1

variations of a gene

Question 2

define genotype

Answer 2

genetic constitution of an organism

Question 3

define phenotype

Answer 3

expression of genetic constitution and its interaction with the environment

Question 4

what is meant by heterozygous?

Answer 4

different alleles at a specific locus on each homologus chromosome

Question 5

what is meant by homozygous?

Answer 5

same alleles at a specific locus on each homologus chromosome

Question 6

explain what is meant by dominant allele?

Answer 6

always expressed in the phenotype

Question 7

explain what is meant by recessive allele?

Answer 7

isn’t expressed in the phenotype

only expressed if homozygous recessive

Question 8

what is meant by codominant alleles?

Answer 8

both alleles are expressed in the phenotype

Question 9

what are genetic diagrams used for?

Answer 9

to illustrate possible genotypes of offspring from 2 parents and the probability of each occuring

Question 10

what is monohybrid inheritance?

Answer 10

inheritance of a characteristic controlled by a single gene

Question 11

what is dihybrid inheritance?

Answer 11

inhertiance of a characteristic controlled by 2 different genes

Question 12

how does dihybrid inheritance occur?

Answer 12

1. an allele from one pair of chromosome enters a gamete with either allele from the other pair
2. due to independant segregation

Question 13

what is the expected ratio of offspring phenotype when 2 heterozygous parents reproduce? (monohybrid inheritance)

Answer 13

3:1

Question 14

what is the expected ratio of offspring phenotype when 2 heterozygous co-dominant parents reproduce? (monohybrid inheritance)

Answer 14

1:2:1

Question 15

what is the expected ratio of offspring phenotype when 2 homozygoys co-dominant parents reproduce? (monohybrid inheritance)

Answer 15

1:1

Question 16

what is the expected ratio of offspring phenotype when 2 homozygous parents reproduce? (monohybrid inheritance)

Answer 16

no ratio, all the same phenotype

Question 17

what is the expected ratio of offspring phenotype when 2 heterohetero and heterohetero parents reproduce? (dihybrid inheritance)

Answer 17

9:3:3:1

Question 18

what is the expected ratio of offspring phenotype when a heterozygous and a homozygous parent reproduce? (monohybrid inheritance)

Answer 18

1:1

Question 19

what is the expected ratio of offspring phenotype when homo homo and homo homo parents reproduce? (dihybrid inheritance)

Answer 19

no ratio, all the same phenotype

Question 20

what is the expected ratio of offspring phenotype when a heterozygous and homozygous parents reproduce? (monohybrid inheritance)

Answer 20

1:1

Question 21

why arent the observed and the exepected ratio of offsrping phenotype the same in dihybrid inheritance?

Answer 21

1. autosomal linkage

2. crosssing over in meisois occured

Question 22

when does a dominance hierachy occur?

Answer 22

when there is more than 2 alleles for the same gene

Question 23

what does being ‘sex-linked mean’?

Answer 23

gene’s locus is on the sex chromsome

Question 24

why are genes more likely to be x-linked?

Answer 24

1. males have one allele; express recessive x-linked allele as only one copy is present
2. females need to be homozygous recessive to be expressed

Question 25

what is the expected ratio of offspring phenotype when a hetero hetero and homo homo parents reproduce? (dihybrid inheritance)

Answer 25

1:1:1:1

Question 26

Which stats test is used to analysis the data from monohybrid or dihybrid crosses?

Answer 26

1. chi-squared
2. used to find the difference between observed and expected results
3. data is categoric

Question 27

define epistasis

Answer 27

interference of one gene’s expression by another