Skip to main content
Pearson+ LogoPearson+ Logo
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 8f

Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.
If a woman is heterozygous for albinism, an autosomal recessive condition that results in the absence of skin pigment, the proportion of her gametes carrying the allele that allows pigment expression is expected to be 75%.

Verified step by step guidance
1
Step 1: Understand the genetic basis of albinism. Albinism is an autosomal recessive condition, meaning that an individual must inherit two recessive alleles (aa) to express the condition. A heterozygous individual (Aa) carries one dominant allele (A) and one recessive allele (a).
Step 2: Recall the concept of gamete formation during meiosis. In a heterozygous individual (Aa), the alleles segregate equally during gamete formation, resulting in 50% of the gametes carrying the dominant allele (A) and 50% carrying the recessive allele (a).
Step 3: Analyze the statement provided. The statement claims that the proportion of gametes carrying the allele for pigment expression (dominant allele A) is 75%. This is inconsistent with Mendel's law of segregation, which states that alleles segregate equally.
Step 4: Revise the statement to make it correct. The correct proportion of gametes carrying the allele for pigment expression (A) in a heterozygous individual (Aa) is 50%, not 75%.
Step 5: Conclude that the statement is false and provide the corrected information: If a woman is heterozygous for albinism, the proportion of her gametes carrying the allele that allows pigment expression is expected to be 50%.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
3m
Was this helpful?

Key Concepts

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

Heterozygosity

Heterozygosity refers to the presence of two different alleles at a specific gene locus. In the context of albinism, if a woman is heterozygous, she has one normal allele (for pigment production) and one recessive allele (for albinism). This genetic makeup influences the types of gametes she can produce, specifically affecting the expression of traits in offspring.
Recommended video:

Autosomal Recessive Inheritance

Autosomal recessive inheritance occurs when a trait is expressed only when an individual has two copies of the recessive allele. In the case of albinism, an individual must inherit the recessive allele from both parents to exhibit the condition. If only one recessive allele is present, the dominant allele will mask its effect, leading to normal pigmentation.
Recommended video:
Guided course
09:08
Autosomal Pedigrees

Gamete Formation and Allele Distribution

During gamete formation, specifically through meiosis, alleles segregate so that each gamete receives only one allele from each gene pair. For a heterozygous individual (e.g., Aa), the gametes will carry either the dominant allele (A) or the recessive allele (a) in equal proportions, resulting in 50% of the gametes carrying the allele for pigment expression, not 75%.
Recommended video:
Guided course
04:06
Formation of Plant Gametes
Related Practice
Textbook Question

Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.

A test cross between a heterozygous parent and a homozygous recessive parent is expected to produce a 1:1 genotypic and phenotypic ratio.

517
views
Textbook Question

Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.


The outcome of a trihybrid cross is predicted by the law of segregation.

525
views
Textbook Question

Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.

Reciprocal crosses that produce identical results demonstrate that a strain is pure-breeding.

498
views
Textbook Question

Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.


The progeny of a trihybrid cross are expected to have one of 27 different genotypes.

454
views
Textbook Question

Determine whether the statements below are true or false. If a statement is false, provide the correct information or revise the statement to make it correct.

If a dihybrid plant is self-fertilized,

(1) 9/16 of the progeny will have the same phenotype as the F₁ parent.

(2) 1/16 of the progeny will be true-breeding.

(3) 1/2 of the progeny will be heterozygous at one or both loci.

411
views
Textbook Question

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.

426
views