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Ch. 2 - Transmission Genetics
Sanders - Genetic Analysis: An Integrated Approach 3rd Edition
Sanders3rd EditionGenetic Analysis: An Integrated ApproachISBN: 9780135564172Not the one you use?Change textbook
Chapter 2, Problem 48a

A pea plant that has the genotype RrGgwwdd is crossed to a plant that has the rrGgWwDd genotype. The R gene controls round versus wrinkled seed, the G gene controls yellow versus green seed, the W gene controls purple versus white flower, and the D gene controls tall versus short plants. Determine the following;


What are the phenotypes of each plant?

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1
Step 1: Identify the genotype of the first plant (RrGgwwdd) and determine the phenotype for each gene. For each gene, consider the dominant and recessive alleles: R (round) is dominant to r (wrinkled), G (yellow) is dominant to g (green), w (white flower) is recessive to W (purple flower), and d (short) is recessive to D (tall).
Step 2: For the first plant (RrGgwwdd), analyze each gene: Rr results in round seeds (dominant R), Gg results in yellow seeds (dominant G), ww results in white flowers (recessive w), and dd results in short plants (recessive d). Combine these traits to describe the phenotype of the first plant.
Step 3: Identify the genotype of the second plant (rrGgWwDd) and determine the phenotype for each gene. Again, consider the dominant and recessive alleles: rr results in wrinkled seeds (recessive r), Gg results in yellow seeds (dominant G), Ww results in purple flowers (dominant W), and Dd results in tall plants (dominant D).
Step 4: For the second plant (rrGgWwDd), analyze each gene: rr results in wrinkled seeds (recessive r), Gg results in yellow seeds (dominant G), Ww results in purple flowers (dominant W), and Dd results in tall plants (dominant D). Combine these traits to describe the phenotype of the second plant.
Step 5: Summarize the phenotypes of both plants based on the analysis above. The first plant has round seeds, yellow seeds, white flowers, and is short. The second plant has wrinkled seeds, yellow seeds, purple flowers, and is tall.

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Key Concepts

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

Genotype vs. Phenotype

The genotype refers to the genetic makeup of an organism, represented by the alleles it possesses, while the phenotype is the observable physical or biochemical characteristics resulting from the genotype. In this question, understanding the difference is crucial for determining the phenotypes based on the given genotypes of the pea plants.
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Dominant and Recessive Alleles

In genetics, alleles can be dominant or recessive. A dominant allele masks the effect of a recessive allele in a heterozygous genotype. For example, in the R gene controlling seed shape, the R allele (round) is dominant over the r allele (wrinkled), which influences the phenotype of the offspring when determining their traits.
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Punnett Square

A Punnett square is a diagram used to predict the genotypes and phenotypes of offspring from a genetic cross. By organizing the alleles from each parent, it allows for a visual representation of potential combinations, making it easier to determine the resulting phenotypes of the plants in the given cross.
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Related Practice
Textbook Question

The accompanying pedigree shows a family in which one child (II-1) has an autosomal recessive condition. On the basis of this fact alone, provide the following information.

What are the probabilities for each of the possible genotypes for II-2, II-3, and II-4?

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Textbook Question

The accompanying pedigree shows a family in which one child (II-1) has an autosomal recessive condition. On the basis of this fact alone, provide the following information.

What is the probability that all three of the children in generation II who have the dominant phenotype are Aa?

913
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Textbook Question

The accompanying pedigree shows a family in which one child (II-1) has an autosomal recessive condition. On the basis of this fact alone, provide the following information.

What is the chance that among the three children in generation II who have the dominant phenotype, one of them is AA and two of them are Aa? (Hint: Consider all possible orders of genotypes.)

978
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Textbook Question

A pea plant that has the genotype RrGgwwdd is crossed to a plant that has the rrGgWwDd genotype. The R gene controls round versus wrinkled seed, the G gene controls yellow versus green seed, the W gene controls purple versus white flower, and the D gene controls tall versus short plants. Determine the following;


What proportion of the progeny are expected to have the genotype RrGGwwDd?

431
views
Textbook Question

A pea plant that has the genotype RrGgwwdd is crossed to a plant that has the rrGgWwDd genotype. The R gene controls round versus wrinkled seed, the G gene controls yellow versus green seed, the W gene controls purple versus white flower, and the D gene controls tall versus short plants. Determine the following;


What proportion of the progeny are expected to have the genotype rrggwwdd?

486
views
Textbook Question

A pea plant that has the genotype RrGgwwdd is crossed to a plant that has the rrGgWwDd genotype. The R gene controls round versus wrinkled seed, the G gene controls yellow versus green seed, the W gene controls purple versus white flower, and the D gene controls tall versus short plants. Determine the following:

What proportion of the progeny are expected to be round, yellow, purple, and tall?

495
views