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

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

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

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.

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

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

white and wrinkled

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

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

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