Test 2

Question 1

What do you get if you cross a monohybrid or dihybrid homozygote x homozygote?

Answer 1

a heterozygote

Question 2

For monohybrid crosses, what ratio do you get if you cross a heterozygote x heterozygote?

Answer 2

3:1 ratio

Question 3

For monohybrid crosses, what ratio do you get if you cross a heterozygote x homozygous recessive?

Answer 3

1:1 ratio

Question 4

For dihybrid crosses, what ratio do you get if you cross a heterozygote x heterozygote?

Answer 4

9:3:3:1 ratio

Question 5

For dihybrid crosses, what ratio do you get if you cross a heterozygote x homozygous recessive?

Answer 5

1:1:1:1 ratio

Question 6

Do reciprocal crosses matter? If you have a male red eyed fly X brown female or brown-eyed X red female?

Answer 6

RR X rr = Rr
rr X RR = Rr

Only matters for sex-linked genes

Question 7

What kind of cross is this and what would the ratio be?

Aa X Aa

Answer 7

Monohybrid

3:1

Question 8

What kind of cross is this and what would the ratio be?

Aa X aa

Answer 8

Monohybrid

1:1

Question 9

What kind of cross is this and what would the ratio be?

AaBb X AaBb

Answer 9

Dihybrid

9:3:3:1

Question 10

What kind of cross is this and what would the ratio be?

AaBb X aabb

Answer 10

Dihybrid

1:1:1:1

Question 11

What kind of cross is this and what would the ratio be?

AaBbCc X AaBbCc

Answer 11

Trihybrid

27:9:9:9:3:3:3:1

Question 12

What kind of cross is this and what would the ratio be?

AaBbCc X aabbcc

Answer 12

Trihybrid

1:1:1:1:1:1:1:1

Question 13

What were Mendel’s four postulates?

Answer 13

1. Unit Factors in Pairs
2. Dominance/Recessiveness
3. Random Segregation
4. Independent Assortment

Question 14

What is Mendel’s postulate, Unit Factors in Pairs?

Answer 14

Homologous Chromosomes contain the same genes

• each chromosome has a copy of the same gene called an allele
• humans are diploid

Question 15

What is Mendel’s postulate, Dominance/Recessiveness?

Answer 15

One copy of the gene, an allele, may be dominant to the other copy
-heterozygotes express the phenotype of the dominant allele

Question 16

What is Mendel’s postulate, Random Segregation?

Answer 16

Homologous chromosomes segregate into different gametes during meioisis
-Aa -> 1/2 A & 1/2 a

Question 17

What is Mendel’s postulate, Independent Assortment?

Answer 17

Genes on NON-homologous chromosomes sort independently of eachother during meioisis

• can get any combination
• AaBb -> AB & Ab & aB & ab

Question 18

When does the sum rule apply? What is it’s clue word?

Answer 18

When looking for EITHER of 2 or more outcomes of ONE event
-Clue word is “or”

eg. What is the probablility of rolling a 1 or a 2 when rolling a die?
1/6 + 1/6 = 2/6 = 1/3

Question 19

When does the product rule apply? What is the clue word?

Answer 19

When looking at more than one event
-Clue word is “and”

eg. What is the probability of landing on heads each time when flipping a coin 3 times?
1/2 x 1/2 x 1/2 = 1/8

Question 20

How is PKU inherited?

Answer 20

recessive allele

PP = Normal
Pp = Carrier
pp = No enzyme; PKU

Question 21

What do the letters of the binomial expansion equation stand for?

P = ( n! / s!t! ) (p^s) (q^t)

Answer 21

P =  probablity
n = number of events (usually number of offspring)
s = outcome 1
t = outcome 2
p= probability of outcome 1
q= probability of outcome 2

Question 22

When is the binomial expansion equation used?

Answer 22

When you combine product and sum rules and the order of events doesn’t matter.