Activity 3 “PEA-ce together”

OBJECTIVE:
1. Solve problems involving Mendelian Genetics
DIRECTION:
Solve the dihybrid cross following the step-by-step procedure:

Sample Problem Word Problem

1. Read the problem carefully.
Given that axial flower position (A) is
dominant over terminal flower position (a)
while round seed shape(R) is dominant
wrinkled seed shape (r).
A garden pea plant with heterozygous gene
pair for both axial flower and round seed is
crossed with a garden pea plant with
heterozygous gene pair for both axial flower
and round seed. What are the possible
offspring of the cross?

Word Problem

Given that green pod color (G) is
dominant over yellow pod color (g) while
inflated pod (I) is dominant over
constricted pod (i)
A garden pea plant with heterozygous
gene pair for both green and inflated pod
is cross with a garden pea plant with
homozygous gene pair for green and
heterozygous gene pair for inflated pod.
Is there a possibility that a garden pea
plant with a green and inflated pod is
produced from the cross?

2. Identify the parents from the problem then write the GENOTYPE of the
Parents.

PARENT 1: garden pea plant with
heterozygous gene pair for both axial flower
and round seed
(GENOTYPE: AaRr)
PARENT 2: garden pea plant with
heterozygous gene pair for both axial flower
and round seed

PARENT 1:
_____________________________________
(GENOTYPE:___________)
PARENT 2:
_____________________________________
(GENOTYPE:___________)

(GENOTYPE: AaRr)

3. Now, according to the “PRINCIPLE OF SEGREGATION” during gametes
formation, the pair separate. Since the problem deals with two characters it
involved the “PRINCIPLE OF INDEPENDENT ASSORTMENT” which states that
the way one character is being inherited is INDEPENDENT to how the other
character is inherited.

PARENT 1: AaRr
PARENT 2: AaRr
PARENT 1: ___________
PARENT 2: ____________

4. Write the gametes of the first parent on the TOP and the gametes of the
second parent on the SIDE of the Punnett square. Combine the gametes on
the top and side then identify the phenotype inside each box.

AR Ar aR ar
AR
Ar
aR
ar
AARR
axial
round
AARr
axial
round
AaRR
axial
round
AaRr
axial
round
AARr
axial
round
AArr
axial
wrinkled
AaRr
axial
round
Aarr
axial
wrinkled
AaRR
axial
round
AaRr
axial
round
aaRR
terminal
round
aaRr
terminal
round
AaRr
axial
round
Aarr
axial
wrinkled
aaRr
terminal
round
aarr
terminal
wrinkled
_____ _____ _____ _____
______
_____
_____
______ ______ ______ _____
______ ______ ______ _____
______ ______ ______ _____
______ ______ ______ _____
10. Identify the genotypic and phenotypic ratio of the possible offspring of the
cross.

GENOTYPIC RATIO: 1:2:1:2:4:2:1:2:1
AARR-1
AARr-2
AArr-1
AaRR-2
AaRr-4
Aarr-2
aaRR-1
aaRr-2
aarr-1
PHENOTYPIC RATIO: 9:3:3:1
axial, round-9
axial, wrinkled-3
terminal, round-3
terminal, wrinkled-1

GENOTYPIC RATIO: _________________
PHENOTYPIC RATIO: ________________

5. Answer the problem.
The following possible offspring of the cross
are:
1. Garden pea plant with axial flower and
round seed
2. Garden pea plant with axial flower and
wrinkled seed
3. Garden pea plant with terminal flower
and round seed
4. Garden pea plant with terminal flower
and wrinkled seed
_______________________________________

100 points sa makakasagot