Ch. 14 - Mendel and the Gene

Freeman - Biological Science 7th Edition

Freeman7th EditionBiological ScienceISBN: 9783584863285Not the one you use?Change textbook

Freeman 7th Edition

Ch. 14 - Mendel and the Gene

Problem 8

Chapter 14, Problem 8

In garden peas, yellow seeds (Y) are dominant to green seeds (y), and inflated pods (I) are dominant to constricted pods (i). Suppose you have crossed YYII parents with yyii parents. Draw the F1 Punnett square and predict the expected F1 phenotype(s).

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Identify the genotypes of the parent plants. In this case, one parent is YYII (homozygous dominant for both traits) and the other parent is yyii (homozygous recessive for both traits).

Set up a Punnett square for the F1 generation. Since both traits are being considered, you will need to use a dihybrid cross, which involves a 4x4 grid because each parent can produce four different types of gametes based on the combination of alleles they can pass on.

Determine the possible gametes for each parent. The YYII parent can only produce YI gametes because both alleles are homozygous dominant. The yyii parent can only produce yi gametes because both alleles are homozygous recessive.

Fill in the Punnett square by crossing each gamete from the YYII parent with each gamete from the yyii parent. Since all gametes from the YYII parent are YI and all gametes from the yyii parent are yi, all resulting offspring in the F1 generation will have the genotype YyIi.

Predict the phenotypes of the F1 generation based on the genotypes. Since Y (yellow seeds) and I (inflated pods) are dominant, all F1 offspring with the genotype YyIi will exhibit yellow seeds and inflated pods.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Mendelian Genetics

Mendelian genetics is the study of how traits are inherited through generations, based on the principles established by Gregor Mendel. It involves understanding dominant and recessive alleles, where dominant alleles mask the expression of recessive ones. In this case, yellow seeds (Y) and inflated pods (I) are dominant traits, while green seeds (y) and constricted pods (i) are recessive.

Punnett Square

A Punnett square is a diagram used to predict the genotypes and phenotypes of offspring from a genetic cross. It organizes the possible combinations of alleles from each parent, allowing for a visual representation of inheritance patterns. In this scenario, the Punnett square will show the combinations of Y and I alleles from the YYII parents with y and i alleles from the yyii parents.

Phenotype

Phenotype refers to the observable physical characteristics or traits of an organism, which result from the interaction of its genotype with the environment. In this question, the expected F1 phenotypes will be determined by the dominant traits inherited from the YYII parents, leading to yellow seeds and inflated pods in the offspring, regardless of the recessive traits from the yyii parents.

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Genotype & Phenotype

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Textbook Question

In peas, purple flowers are dominant to white. If a purple-flowered, heterozygous plant were crossed with a white-flowered plant, what is the expected ratio of genotypes and phenotypes among the F1 offspring? If two of the purple-flowered F1 offspring were randomly selected and crossed, what is the expected ratio of genotypes and phenotypes among the F2 offspring?

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Textbook Question

In flies, small wings are recessive to normal wings. If a cross between two flies produces 8 small-wing offspring and 28 normal-wing offspring, what are the most likely genotypes of the parents? (Use S to represent the normal-wing allele and s to represent the short-wing allele.)

In garden peas, yellow seeds (Y) are dominant to green seeds (y), and inflated pods (I) are dominant to constricted pods (i). Suppose you have crossed YYII parents with yyii parents. Draw the F2 Punnett square. Based on this Punnett square, predict the expected phenotype(s) in the F2 generation and the expected frequency of each phenotype.

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Textbook Question

In garden peas, yellow seeds (Y) are dominant to green seeds (y), and inflated pods (I) are dominant to constricted pods (i). Suppose you have crossed YYII parents with yyii parents. Draw the F1 Punnett square and predict the expected F1 phenotype(s).

945

views

Textbook Question

In garden peas, yellow seeds (Y) are dominant to green seeds (y), and inflated pods (I) are dominant to constricted pods (i). Suppose you have crossed YYII parents with yyii parents. List the genotype(s) of gametes produced by F1 individuals.

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