A researcher studied six independently assorting genes in a plant. Each gene has a dominant and a recessive allele: R black stem, r red stem; D tall plant, d dwarf plant; C full pods, c constricted pods; O round fruit, o oval fruit; H hairless leaves, h hairy leaves; W purple fl ower, w white fl ower. From the cross (P1) Rr Dd cc Oo Hh Ww (P2) Rr dd Cc oo Hh ww

The question is not complete so I am writing the complete question below:

A researcher studied six independently assorting genes in a plant. Each gene has a dominant and a recessive allele: R black stem, r red stem; D tall plant, d dwarf plant; C full pods, c constricted pods; O round fruit, o oval fruit, H hairless leaves, b hairy leaves; W purple flower, w white flower. From the cross (P1) Rr Dd cc Oo Hh Ww * (P2) Rr dd Cc oo Hh ww,

(a) How many kinds of gametes can be formed by P1?

(b) How many genotypes are possible among the progeny of this cross?

(c) How many phenotypes are possible among the progeny?

(d) what is the probability of obtaining the Rr Dd ㏄ Oo bb ww genotype in the progeny?

(e) What is the probability of obtaining a black, dwarf, con - stricted, oval, hairy, purple phenotype in the progeny?

Answer:

(a) 32

(b) 144

(c) 64

(d) 1/128

(e) 3/256

Explanation:

(a) We have P1: Rr Dd cc Oo Hh Ww

Rr can form 2 gametes - R r

Dd can form 2 gametes - D d

cc can form only one type of gamete - c

Oo can form 2 gametes - O o

Hh can form 2 gametes - H h

Ww can form 2 gametes W w

Kinds of gametes formed by p1 = 2 x 2 x 1 x 2 x 2 x 2 = 32

(b) We have

P1: Rr Dd cc Oo Hh Ww

P2: Rr dd Cc oo Hh ww

We can construct a Punnet Square for each gene and see how many kinds of genotypes are possible among the progeny.

Rr x Rr

R r

R RR Rr

r Rr rr

3 different types of genotypes are possible

Dd x dd

D d

d Dd dd

d Dd dd

2 different types of genotypes are possible

cc x Cc

C c

c Cc cc

c Cc cc

2 different types of genotypes are possible

Oo x oo

O o

o Oo oo

o Oo oo

2 different types of genotypes are possible

Hh x Hh

H h

H HH Hh

h Hh hh

3 different types of genotypes are possible

Ww x ww

W w

w Ww ww

w Ww ww

2 different types of genotypes are possible

Genotypes possible among the progeny = 3 x 2 x 2 x 2 x 3 x 2 = 144

(c) Only two types of phenotypes are possible in the progeny since the heterozygous genotype also shows the phenotype of the dominant allele. So, only 2 phenotypes are possible for each gene.

Phenotypes possible among the progeny = 2 x 2 x 2 x 2 x 2 x 2 = 64

(d) To caulculate probability of Rr Dd cc Oo hh ww genotype in the progeny, we need to look at each of the Punnet squares and calculate the probability for each genotype.

We can see that 2 Rr genotypes are present in the Punnet square out of 4 so the probability P (Rr) is:

P (Rr) = 2/4 = 1/2

Similarly,

P (Dd) = 1/2

P (cc) = 1/2

P (Oo) = 1/2

P (hh) = 1/4

P (ww) = 1/2

probability of obtaining the Rr Dd ㏄ Oo bb ww genotype in the progeny =

1/2 x 1/2 x 1/2 x 1/2 x 1/4 x 1/2 = 1/128

(e) For obtaining a black, dwarf, con - stricted, oval, hairy, purple phenotype in the progeny, we need to specify the genotypes for each of these phenotypes and then calculate the probability for each of them.

Black = RR and Rr genotypes = 3/4 (from Punnet square)

Dwarf = dd genotype = 1/2

Constricted = cc genotype = 1/2

Oval = oo genotype = 1/2

Hairy = hh genotype = 1/4

Purple = Ww genotype = 1/2

Probability = 3/4 x 1/2 x 1/2 x 1/2 x 1/4 x 1/2 = 3/256