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3.5.3.1. More codominance and intermediate inheritance problems 2

Solved problems of codominance and intermediate inheritance. (Page 15)

Genetics problem 113

One farmer crossed long radish plants with round radish plants and observed that all the offspring consisted of oval radish plants.

a) Explain reasonably what type of inheritance controls the shape of radishes.

b) Indicate the genotypes of the three types of plants.

c) If the farmer crossed oval radish plants with long radish plants, what percentage of the offspring would be expected to be round radishes? Reason for your answer by representing the scheme of the possible crossover.

Genetics problem 114

When a cross was made between butterflies with gray wings, an offspring of 30 butterflies with black wings, 30 with white wings and 60 with gray wings were obtained. Determine (3 points):

a) What type of inheritance gives rise to these phenotypes?
b) The genotypic and phenotypic proportions of the offspring.
c) If the total number of butterflies obtained had been 200, how many would be white, black and gray with greater probability.

Genetics problem 115

A farmer crosses two pure specimens: a female with blue scales (A) with a male with red scales (R). Each of the individuals of the F1 offspring that results from the cross has a mixture of blue and red scales.

a) Indicate the parental genotypes and the F1 individuals.         
b) Explain reasonably what type of inheritance it is.
c) Indicate the genotypic and phenotypic proportions of the F2 resulting from the crossing of two individuals of the F1.

Genetics problem 116

Thalassemia is a type of anemia that occurs in humans. It has two forms, minor and major. Severely affected (major) individuals are homozygous recessive (TMTM) for one gene. Little affected people (minor) are heterozygous for this gene. Normal individuals  are homozygous dominant for the gene (TNTN). If all individuals with thalassemia  major die before reaching sexual maturity,

a) What proportion of the children of a couple  in which the man is normal and the woman suffers from thalassemia minor will reach adults?

b)  What will be the genotypic and phenotypic proportions if the parents are two people with  thalassemia minor? In each case, give reasons for your answer.

Genetics problem 117

Answer the following questions regarding schemas A and B.

a) What type of inheritance is represented in A?

b) What type of inheritance is represented in B?

c) What genotype and phenotype will the offspring resulting from the crossing of two individuals with black spots have? List the percentages.

d) What is the difference between the inheritances represented in A and B?

e) Could the white cow in scheme B come from two gray parents? And what about a gray parent and a black parent? Reason the answers with the corresponding cross.

 

Genetics problem 118

A black butterfly is crossed with a gray butterfly and 36 black and 36 gray butterflies are obtained. Subsequently, a gray butterfly is crossed with a white one and 36 white and 36 gray butterflies are obtained.

a)  Explain if it is a case of intermediate or dominant inheritance.

b) Make the two crosses  mentioned above, indicating which are the genotypes of the butterflies that are crossed and those of the d scene obtained.

Genetics problem 119

The coat colors of a certain breed of cattle are due to a pair of codominant alleles. Red is determined by the genotype CRCR, roan (mixture of red and  white) by CRCB  and the blank CBB. If we cross a pair of roan color. What genotypic and phenotypic ratio do we expect from their progeny?

Genetics problem 120

Crossing two pink flowers produces offspring with 50% pink flowers, 25% red flowers and 25% white flowers.

a) Do these observations contradict Mendel's laws?

b) What can we deduce regarding the genotypes of the parents?

c) If afterwards two white flowers are crossed from those obtained in the previous crossing, what percentage of pink flowers should be expected in the offspring?

Genetics problem 121

One farmer crossed long radish plants with round radish plants and observed that all the offspring consisted of oval radish plants.

a) Explain reasonably what type of inheritance controls the shape of radishes. (0,4)
b) Indicate the genotypes of the three types of plants. (0.45)
c) If the farmer crosses oval radish plants with long radish plants, what percentage of the offspring would be expected to be round, long, and oval radishes? Reason for your answer by representing the scheme of the possible crossover. (0.75)
d) Define locus and backcrossing. (0.4)

Genetics problem 122

A farmer from La Murta has a herd of goats and observes that whenever he crosses a long-eared female with a short-eared male, he obtains all the offspring with medium-sized ears. However, when he crossed medium-eared animals with each other, he obtained 32 long-eared, 65 medium-eared and 33 short-eared goats.

a) What is the type of inheritance that occurs in the transmission of this character called? Give reasons for the answer. (1 point)
b) Indicate, by making the corresponding crosses, the genotypic and phenotypic proportions of F1 and F2. (1 point)


         

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Biology and Geology teaching materials for Compulsory Secondary Education (ESO) and Baccalaureate students.