Inheritance Extra practice

Question 1

Homozygous and Heterozygous

Answer 1

Homozygous have 2 identical alleles of a gene while Heterozygous have 2 different alleles of a gene

Question 2

Carrier

Answer 2

An individual that has one copy of a recessive allele that causes a genetic disease in individuals who are homozygous for this allele

Question 3

Phenotypic Plasticity

Answer 3

An organism’s ability to change its phenotype in response to environmental changes without requiring genetic mutations

Question 4

The Fundamental Laws of Inheritance

Answer 4

The Law of Segregation: Pairs of alleles of a gene separate during gamete formation

The Law of Independent Assortment: Two or more pairs of alleles segregate independently of each other as a result of meiosis in Metaphase I

The Law of Dominance: An organism with alternate forms of a gene will express the dominant form

Question 5

Crossing 2 Homo and Hetero

Answer 5

Crossing 2 Homozygous, ratio is 1:0

Crossing 2 Heterozygous, ratio is 3:1

Crossing hetero with homo recessive, ratio is 1:1

Question 6

Incomplete Dominance

Answer 6

One allele for a trait is not expressed completely over its paired allele, thus having an intermediate where neither allele is formed

Question 7

Co-dominance

Answer 7

Two dominant alleles of the same gene are present and contribute to the phenotype which violates the Law of Dominance

Question 8

Blood Groups and Alleles

Answer 8

A - I^A
B - I^B
IA - I^AI^B
O - i

A and B code for enzymes that add specific sugars to a glycoprotein on the RBC

Question 9

Gene that Develops Testes

Answer 9

SRY

Question 10

Autosomal Dominant

Answer 10

Appears almost in both males and females equally

All affected individuals must have an affected parent

Trait doesn’t skip generation

Unaffected parents must produce unaffected offspring

Affected parents can have unaffected child

Question 11

Autosomal Recessive

Answer 11

Appears almost in both males and females equally

Unaffected parents can have unaffected offspring

Trait skips generation

Affected parents must produce affected offspring

Question 12

Sex-linked Dominant

Answer 12

Common in females

If a male shows a trait, then all his daughters and mother must

An unaffected mother can not have affected sons

Question 13

Sex-linked Recessive

Answer 13

Common in males

If a female shows a trait, then all her sons and father must

An unaffected mother can have affected son if she is a carrier

Question 14

Discontinuous VS Continuous Variation

Answer 14

Results in limited amount of phenotypes and no in-betweens
Results in range of phenotypes with in-betweens

Tend to be qualitative
Tend to be quantitative

Controlled by one gene
Controlled by multiple genes

Unaffected by environment
Affected by environment

Shown in a bar graph with separate bars
Bell shaped curve

Example is human blood group
Example is skin color

Question 15

Skin Color Factors

Answer 15

Polygenic Inheritance

Environmental Factors

Question 16

Difference between DNA Segregation and Independent Assortment

Answer 16

Pairs of alleles of a gene separate randomly during gamete formation

The independent segregation of the alleles of two genes of each other so that the outcome with each gene has no effect on the outcome of the other

Question 17

Unlinked Genes

Answer 17

Genes found on separate chromosome pair

Chromosomes segregate independently due to meiosis

Recombination is due to crossing over and independent assortment

Gametes will include parental chromosomes and recombinants, which take up about 50% of the offspring

Represented as AaBb

Question 18

Linked Genes

Answer 18

Genes are found on the same chromosome pair

Chromosomes don’t assort independently and tend to be inherited together

Recombination only occurs if crossing over occurs

The closer two alleles are on a chromosome, the less likely crossing over will occur, vice versa

Have fewer recombinants than unlinked genes

Represented as AB//ab

Question 19

Ratio of Unlinked Genes

Answer 19

Hetero with Hetero = 9:3:3:1

Hetero with Homo recessive = 1:1:1:1

Question 20

Parental VS Recombinant Geno and Phenotypes

Answer 20

Phenotypes of offspring often resemble (at least 1) parents
Phenotypes of offspring differ from both parents

Genotype shows that traits are either dominant or recessive
Genotype shows that one trait is dominant and one recessive

Question 21

Inheritance Diseases Examples

Answer 21

Huntington - Autosomal Dominant

Cystic Fibrosis and Phenylketonuria - Autosomal Recessive

Sickle Cell Anemia - Autosomal Co-dominance

Hemophilia and Red-green Color Blindness - Sex-linked Recessive