In a cross between a black and a white guinea pig, all members of the F₁ generation are black. The F₂ generation is made up of approximately 3/4 black and 1/4 white guinea pigs. Diagram this cross, showing the genotypes and phenotypes.

In the datura plant, purple flower color is controlled by a dominant allele, P. White flowers are found in plants homozygous for the recessive allele p. Suppose that a purple-flowered datura plant with an unknown genotype is self-fertilized and that its progeny are 28 purple-flowered plants and 10 white-flowered plants.

Use the results of the self-fertilization to determine the genotype of the original purple-flowered plant.

In chickens, a condition referred to as 'creeper' exists whereby the bird has very short legs and wings and appears to be creeping when it walks. If creepers are bred to normal chickens, one-half of the offspring are normal and one-half are creepers. Creepers never breed true. If bred together, they yield two-thirds creepers and one-third normal. Propose an explanation for the inheritance of this condition.

In a cross between a black and a white guinea pig, all members of the F₁ generation are black. The F₂ generation is made up of approximately 3/4 black and 1/4 white guinea pigs. Two different matings were made between black members of the F₂ generation, with the following results. Diagram each of the crosses.

Cross Offspring

Cross 1 All black

Cross 2 3/4 black, 1/4 white

In a cross between a black and a white guinea pig, all members of the F₁ generation are black. The F₂ generation is made up of approximately 3/4 black and 1/4 white guinea pigs. What will the offspring be like if two F₂ white guinea pigs are mated?

The dorsal pigment pattern of frogs can be either 'leopard' (white pigment between dark spots) or 'mottled' (pigment between spots appears mottled). The trait is controlled by an autosomal gene. Males and females are selected from pure-breeding populations, and a pair of reciprocal crosses is performed. The cross results are shown below.

    Cross 1:  P₁: Male leopard x male mottled

             F₁: All mottled

             F₂: 70 mottled, 22 leopard

    Cross 2:  P₁: Male mottled x female leopard

             F₁: All mottled

             F₂: 50 mottled, 18 leopard

Propose two different genetic crosses that would allow you to determine the genotype of one mottled frog from the F₂ generation.

The dorsal pigment pattern of frogs can be either 'leopard' (white pigment between dark spots) or 'mottled' (pigment between spots appears mottled). The trait is controlled by an autosomal gene. Males and females are selected from pure-breeding populations, and a pair of reciprocal crosses is performed. The cross results are shown below.

    Cross 1:  P₁: Male leopard x male mottled

             F₁: All mottled

             F₂: 70 mottled, 22 leopard

    Cross 2:  P₁: Male mottled x female leopard

             F₁: All mottled

             F₂: 50 mottled, 18 leopard

In the F₂ progeny from both crosses, what proportion is expected to be homozygous? What proportion is expected to be heterozygous?

The dorsal pigment pattern of frogs can be either 'leopard' (white pigment between dark spots) or 'mottled' (pigment between spots appears mottled). The trait is controlled by an autosomal gene. Males and females are selected from pure-breeding populations, and a pair of reciprocal crosses is performed. The cross results are shown below.

    Cross 1:  P₁: Male leopard x male mottled

             F₁: All mottled

             F₂: 70 mottled, 22 leopard

    Cross 2:  P₁: Male mottled x female leopard

             F₁: All mottled

             F₂: 50 mottled, 18 leopard

Compare and contrast the results of the reciprocal crosses in the context of autosomal gene inheritance.

The dorsal pigment pattern of frogs can be either 'leopard' (white pigment between dark spots) or 'mottled' (pigment between spots appears mottled). The trait is controlled by an autosomal gene. Males and females are selected from pure-breeding populations, and a pair of reciprocal crosses is performed. The cross results are shown below.

    Cross 1:  P₁: Male leopard x male mottled

             F₁: All mottled

             F₂: 70 mottled, 22 leopard

    Cross 2:  P₁: Male mottled x female leopard

             F₁: All mottled

             F₂: 50 mottled, 18 leopard

Which of the phenotypes is dominant? Explain your answer.