CROSS PREDICTIONS

Red x red (both heterozygous)

3 red, 1 white

A grid system used to predict possible combinations of genes due to random fertilization

Punnett square

A phenotypic ratio for a dihybrid cross is predicted to be 9:3:3:1. The experimental values are purple smooth = 75, white smooth = 28, purple wrinkled = 24, white wrinkled = 8. Account for the difference between the expected and experimental values.

The purple smooth allele is DOMINANT. The white wrinkled allele is RECESSIVE. Receiving a purple smooth allele is more likely than getting a white wrinkled allele. The ratio would be 75:28:24:8.

Red (heterozygous) x red (homozygous)

all red

With the following crosses of pea plants, give the flower color of offspring and the ratio expected (redis dominant). Red x red (both homozygous)

all red

Suppose you have monohybrid pea plants in your garden and find that they produce round seed to wrinkled seeds in the ratio of 3:1. If the allele are designated (R & r) respectively, what is the probable Phenotype of the parents?

all round

A cross between plants which differ in only two traits is a ________ cross

dihybrid

Breeding of individuals which have genes for two different characteristics

dihybrid cross

To determine if a particular plant is homozygous or heterozygous, you would have to test cross with a __________ recessive.

homozygous

A type of cell division used to produce gametes

meiosis

(purple smooth = 75, white smooth = 28, purple wrinkled = 24, white wrinkled = 8) Which alleles are dominant?

purple and smooth

Breeding the individual with the dominant trait to a homozygous recessive for that trait

test cross

(purple smooth = 75, white smooth = 28, purple wrinkled = 24, white wrinkled = 8) Which alleles are recessive?

white and wrinkled

Red (heterozygous) x white (homozygous)

2 red, 2 white

The female genotype of the previous problem is:

• TT • homozygous

If a male genotype is Tt and the female genotype is TT, then what are the phenotypic ratios for tall and short corn? Phenotype Genotype ratio TT:Tt

• all tall • 1:1

A test cross is a cross between the unknown ________ genotype and a homozygous _________.

• dominant • recessive

In a dihybrid cross, the F2 will have nine genotypes, but only four phenotypes because the ____________ genes cause the ________ traits to mask the _________ traits.

• heterozygous • dominant • recessive

Complete a Punnett square for the cross-pollination of a red flower (RR) and a pink flower (Rr).

ㅤㅤRㅤㅤR Rㅤ RRㅤ RR r ㅤ Rrㅤ Rr

Suppose you have monohybrid pea plants in your garden and find that they produce round seed to wrinkled seeds in the ratio of 3:1. If the allele are designated (R & r) respectively, what is the probable genotypes of the wrinkled seeds which were produced?

rr only

With the parents from the previous problem (white WW, black ww) give the phenotype and genotype ratios for this cross. Phenotype: genotype ratio Ww:ww

• ½ white ½ black • 1:1

Diagram the genotypes of the P₁ pea plants from the previous four questions by placing the correct answer on its correct place.

⁣ ⁣ ⁣⁣ 〡R⠀〡r ➖➕➖➕➖ R 〡RR〡Rr ➖➕➖➕➖ r⠀〡Rr〡rr

The phenotypic ratio for the F2 generation in a dihybrid cross will theoretically be _____.

9:3:3:1

All the gene pairs from one parent can congregate in one gamete and those from the other parent in other gamete.

False

Suppose you have monohybrid pea plants in your garden and find that they produce round seed to wrinkled seeds in the ratio of 3:1. If the allele are designated (R & r) respectively, what is the probable genotypes of the round seeds which were produced?

RR & Rr

The results of a test cross of a tall tomato plant was 100% tall. Fill in the punnett square if all the recessive alleles (genes) came from pollen during the cross test.

⁣ ⁣ ⁣⁣ 〡T⠀〡T ➖➕➖➕➖ t 〡Tt〡Tt ➖➕➖➕➖ t⠀〡Tt〡Tt

(purple smooth (PR)= 75, white smooth (pR)= 28, purple wrinkled (Pr)= 24, white wrinkled (pr)= 8) Using symbols, diagram a cross that would give these results by completing the punnet square by placing the correct answers in their appropriate spot.

〡 PPRR〡PPRr〡PpRR〡PpRr 〡 〡➖➖➖➕➖➖➕➖➖➕➖➖➖ 〡 〡 PPRr 〡PPrr〡PpRr⁣⁣〡Pprrㅤ〡 〡➖➖➖➕➖➖➕➖➖➕➖➖➖ 〡 〡 PpRR〡PpRr〡ppRR〡ppRr 〡 〡➖➖➖➕➖➖➕➖➖➕➖➖➖ 〡 〡 PpRr 〡Pprr〡ppRr〡pprrㅤ 〡

Complete a Punnett square that shows a test cross for a tall pea plant (RR x rr). Place the plant to be tested at the top of the Punnett Square.

ㅤㅤRㅤ R rㅤ Rrㅤ Rr rㅤ Rrㅤ Rr

Complete a Punnett square for the cross-pollination of a female (TT) and a male (Tt). Write in the correct answers to complete the square.

ㅤㅤTㅤㅤT Tㅤ TTㅤ TT tㅤ TtㅤㅤTt