Name:_____________________________
Date:_________________
Period:____
Mendelian Genetics Study Guide
Directions: Since this unit has us completing Genetic Problems. It is best to write solve the
problems directly on this sheet. Please place all answers on this study guide. The textbook
pages are Prentice Hall pp. 110-123.
_____ 1. Describe and draw the 2 steps of Gregor Mendel’s genetic experiments with pea plants. Go to
your guided notes and look at the section titled “Mendel’s Experiments” Write a description of
each step and draw a picture.
STEP 1
STEP 2
_____2. Do you know your genetic vocabulary? Work through the problems #1-3 below. Write the
answers directly on this sheet:
a.
.
Ho
He
Ho
He
He
Ho
TT, dd, FF
b.
Blue
Blue
Green
c.
TT, Tt
tt
Appendix_Science7
Name:_____________________________
Date:_________________
Period:____
_____3. Are you able to write GENOTYPIC and PHENOTYPIC ratios after solving a Punnett Square?
Complete the problems a & b below directly on this sheet.
a. In guinea pigs, Black fur (B) is dominant over white fur (b). A heterozygous black
guinea pig crossed with a white guinea pig.
Bb x bb
a. Show the Punnett square below. Same square as R's below. Just use B's!
b. Write the genotypic ratio. Make sure to label the ratio.
0 BB: 2Bb: 2bb
c. Write the phenotypic ratio. Make sure to label the ratio.
2 Black fur: 2 white fur
b. In the kingdom of Seals, the gene for the length of whiskers has two alleles. The dominant
allele (W) codes for long whiskers and the recessive allele (w) codes for short whiskers.
One parent is homozygous dominant and the other is heterozygous. Show the Punnett
Square. WW x Ww
a. Write the genotypic ratio. Make sure to label the ratio.
2 WW: 2Ww: 0ww
b. Write the phenotypic ratio. Make sure to label the ratio.
4 long whiskers : 0 short whiskers
_____4. Are you able to solve genetic problems using Punnett Squares? Solve problems a & b below.
a.
.
Rr x rr
Rr
Rr – Round; rr – Oval
rr
0 RR: 2 Rr: 2rr
r
r
R
Rr
rr
r
Rr
rr
2 round : 2 oval
50
50
b.
.
TT x tt
TT
t
t
T
Tt
Tt
T
Tt
Tt
tt
Tall – All his children will have a T gene
0 TT : 4 Tt : 0 tt
4 tall : 0 short
No, as they are not homozygous.
Appendix_Science7
Name:_____________________________
Date:_________________
Period:____
_____5. Are you able to solve more challenging problems? Complete a-d below.
a. In pea plants, purple flowers (P) is dominant over white flowers (p). The results of a genetic crossed
yielded 50% white offspring and 50% purple offspring. What are the genotypes of the parents? HINT:
Work backwards using a Punnett square. Pp x pp
b. In humans freckles (F) is dominant over no freckles (f). Both a father and mother have freckles.
However, their son Alex does NOT have freckles. What are the genotypes of the parents? HINT:
Work backwards using a Punnett square. Ff x Ff
c. In guinea pigs, Black fur (B) is dominant over white fur (b). Twelve guinea pigs are born in a litter.
Out of the twelve, 9 have black fur and 3 have white fur. What are the genotypes of the parents?
HINT: What ratio do the offspring remind you of? Work backwards using a Punnett square.
Bb x Bb
d. Tongue Curling (T) is a dominant trait in humans while NOT being able to curl one’s tongue (t) is
recessive. A mother is unable to roll her tongue. Her daughter Kara is also unable to roll her tongue.
What is the genotype of the father?
Dad can be Tt or tt as long as he has one recessive t to offer Kara.
_____ 6.
FLASHBACK: Meiosis
 I am able to state the goal of meiosis.
The goal of meiosis is to make (four) sex cells each having half the genetic material of a
body cell. In sex cells, there are one of each chromosome instead of two. This is so
that when two sex cells join upon fertilization, the normal body cell number of
chromosomes will be restored with half of the DNA coming from a mother and half from
a father.
 I am able to summarize what happens in meiosis I and meiosis II.
Meiosis I - DNA replicates, duplicated chromosome pairs line up, duplicated pairs
separate into two cells
Meiosis II - No DNA replication, duplicated chromosomes line up, duplicated chromosomes
separate into 4 sex cells
Appendix_Science7