T E S T O N T U E S DAY , F E B R U A RY 1 2

GENETICS REVIEW ANSWERS

QUESTION #1

•Who is the “father” of genetics?•Gregor Mendel

QUESTION #2

•What are Mendel’s 3 principles? What do they each say?

1. Principle of Dominance – some alleles are dominant, others are recessive

2. Principle of Segregation – during Meiosis, the alleles separate so that each gamete gets one

3. Principle of Independent Assortment – during Meiosis, the alleles separate independently from each other

QUESTION #3

• Match the following.•Homozygous dominant – two of the same alleles (dominant) for a trait•Homozygous recessive – two of the same alleles (recessive) for a trait•Heterozygous – Two different alleles for a trait

QUESTION #4

•How many alleles are used to determine blood type?• 3 alleles (IA, IB, and i)

•How many blood types are there?• 4 blood types (A, B, AB, and O)

QUESTION #5

•Match the following.• Incomplete dominance – red flower x white flower = pink flower• Codominance – black chicken x white chicken = black & white chicken•Multiple alleles – blood type• Polygenic traits – height, skin color

QUESTION #6

• In a pedigree, what does it mean if the circle or square is shaded?• The person has the trait

QUESTION #7

•Define each of the following:• P generation – the parents of a genetic cross• F1 generation – the offspring of the P generation• F2 generation – the offspring of the F1 generation

QUESTION #8

•Why is colorblindness more common in males than in females?• Because it is carried on the X chromosome and males only have one X

QUESTION #9

•What does dominant mean?• The trait that is expressed

•What does recessive mean?• The trait that is hidden

•Which one is symbolized with a capital letter?• dominant

QUESTION #10

•What disease is caused by a dominant allele?• Achondroplasia•Huntington’s disease

QUESTION #11

•When you flip 1 coin, what is the chance of getting heads?•½

• If you flip 2 coins, what is the chance of getting tails/tails?•¼

QUESTION #12

•Which chromosome are most sex-linked genes found on?• X

QUESTION #13

•What are the sex chromosomes of a female?• XX

•What are the sex chromosomes of a male?• XY

QUESTION #14

•Match the following.• Phenotype – round seed•Genotype – Rr• Allele – R

QUESTION #15

•What are the possible genotypes for the following blood types?• A = IAIA or IAi• B = IBIB or IBi• AB = IAIB

•O = ii

QUESTION #16

•How many chromosomes does a normal human cell have?• 46

QUESTION #17

•What are autosomes?• All of the other chromosomes (not the sex chromosomes)

QUESTION #18

•What is heredity?• The passing of traits from parents to offspring

QUESTION #19

• In a pedigree what does a circle represent?• female

•What does a square represent?•male

QUESTION #20

•Answer the following questions about this family…•What color are the father’s eyes? Brown. What is his genotype? Bb•What color are the mother’s eyes? Blue. What is her genotype? bb• They have a daughter who has brown eyes. What is her genotype? Bb• They have a son who has blue eyes. What is his genotype? bb

QUESTION #21

•A blue-eyed man mates with a woman who is heterozygous for brown eyes. Complete a Punnett square to show their possible offspring.

B

b

b b

Bb Bb

bb bb

QUESTION #21 CONT.

•What are the genotypes of the parents? •Mom – Bb and Dad – bb.

•What are the genotypes and phenotypes of the offspring?•Genotypes – Bb 50%, bb 50%• Phenotypes – brown eyes 50%, blue eyes 50%

QUESTION #22

•When a white, flat squash (WWFF) is crossed with a yellow, round squash (wwff), all the osspring are white and flat (WwFf). Suppose two of these offspring are crossed (WwFf x WwFf). Make a Punnett square of the cross of the two offspring. Give the phenotypes and genotypes of the offspring.

QUESTION #22 CONT.

WWFF WWFf WwFF WwFf

WWFf WWff WwFf Wwff

WwFF WwFf wwFF wwFf

WwFf Wwff wwFf wwff

WF Wf wF wf

WF

Wf

wF

wf

QUESTION #22 CONT.

•Genotypes:•WWFF 1/16, WWFf 2/16, WwFF 2/16, WwFf 4/16, WWff 1/16, Wwff 2/16, wwFF 1/16, wwFf 2/16, wwff 1/16

•Phenotypes:•White, flat 9/16, white, round 3/16, yellow, flat 3/16, yellow, round 1/16