Unlock hundreds more features
Save your Quiz to the Dashboard
View and Export Results
Use AI to Create Quizzes and Analyse Results

OR
Sign inSign in with Facebook
Sign inSign in with Google
Quizzes > Science > Biology

Codominant vs Incomplete Dominance: Take the Quiz!

Ready to master codominance and incomplete dominance practice problems? Let's get started!

Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper cut quiz graphic with red blue flower halves and a purple hybrid bloom on golden yellow background

Ready to explore allele interactions? Take our Codominant vs Incomplete Dominance Quiz and put your genetics skills to the test! By completing each question, you'll boost your confidence in predicting phenotypes from genotypes. In this free quiz, you'll tackle practice problems incomplete dominance and codominance, challenge yourself with practice codominance and incomplete dominance scenarios, and even review a codominance incomplete dominance practice problems answer key to check your answers. Perfect for students and biology enthusiasts eager to master codominance vs incomplete dominance, this quiz sharpens your understanding with real-life examples and instant feedback. Dive in now and unlock new insights - then keep the momentum going with our inheritance patterns quiz or take a broader genetics quiz !

What best describes codominance in genetics?
One allele is completely masked by the other
Alleles blend to produce an intermediate phenotype
Both alleles are fully expressed in the heterozygote
Alleles segregate into separate gametes without interaction
Codominance occurs when both alleles at a locus are simultaneously expressed in the heterozygote, resulting in a phenotype that shows both traits without blending. It differs from complete dominance where one allele masks the other. Neither allele is recessive, so both contribute. source
What is the phenotypic outcome of incomplete dominance?
Heterozygotes revert to the wild-type phenotype
Heterozygotes show an intermediate or blended phenotype
Heterozygotes express both traits fully
Heterozygotes express only the dominant trait
In incomplete dominance, neither allele is completely dominant, so the heterozygote phenotype is intermediate between the two homozygotes. This results from a reduced level of functional gene product from each allele. The traits blend rather than one masking the other. source
Which of these is a classic example of codominance?
Yellow seeds masking green seeds in peas
Pink flowers from red and white snapdragon parents
Tall plants from a tall and a short parent
Human AB blood type expressing both A and B antigens
The human AB blood group is the textbook example of codominance because IA and IB alleles are both fully expressed in heterozygotes, producing both A and B antigens. Snapdragon flowers are an example of incomplete dominance, not codominance. Mendelian pea traits illustrate complete dominance. source
In a snapdragon exhibiting incomplete dominance, what genotype produces a pink flower?
RW
RrWw
WW
RR
Snapdragon flower color shows incomplete dominance: RR yields red, WW yields white, and RW yields a pink intermediate. The heterozygote has one red allele and one white allele that blend. No allele completely dominates in this trait. source
What type of inheritance do the IA and IB alleles of the human ABO blood group demonstrate when present together?
Polygenic inheritance
Incomplete dominance
Complete dominance
Codominance
IA and IB are codominant alleles because a person with both alleles expresses both A and B antigens on red blood cells simultaneously. They do not blend or mask one another. This distinguishes codominance from incomplete dominance. source
In a cross of two roan cattle (codominant red and white coat colors), what is the expected F2 phenotypic ratio?
1 red : 1 white
1 red : 2 roan : 1 white
3 red : 1 white
2 red : 1 roan : 1 white
In codominance, the F2 generation from heterozygous crosses (RW × RW) yields a 1:2:1 ratio of phenotypes: red (RR), roan (RW), and white (WW). The heterozygotes express both pigments equally as roan. This mirrors the Mendelian genotypic ratio but shows distinct phenotypes. source
At the molecular level, how do codominance and incomplete dominance typically differ?
Codominance involves two functional proteins expressed equally; incomplete dominance arises when one allele produces a protein with reduced activity leading to an intermediate phenotype
Codominance results from alleles forming protein dimers; incomplete dominance results from dominant lethal alleles
Codominance only occurs in sex-linked traits; incomplete dominance only occurs in autosomal traits
Codominance involves gene silencing; incomplete dominance involves gene duplication
In codominance both alleles encode functional proteins that are fully expressed in the heterozygote, producing distinct traits simultaneously. In incomplete dominance one allele produces less or a partially functional protein, resulting in a blended intermediate phenotype. The molecular basis often involves protein quantity or activity rather than all-or-none expression. source
In an F2 generation showing a 1:2:1 phenotypic ratio of red:pink:white flowers, how can you determine if the trait is codominant or incompletely dominant?
Measure allele frequencies in gametes directly
Sequence the F3 generation genomes
Examine the heterozygote phenotype for blending versus distinct patchwork of traits
Perform a test cross with a homozygous dominant parent
Both codominance and incomplete dominance can yield a 1:2:1 ratio in the F2, so the phenotypic appearance of the heterozygote is the key. In incomplete dominance the heterozygote shows a uniform blend, while in codominance distinct traits coexist or are expressed separately. A close inspection of heterozygotes clarifies the pattern. source
Which molecular mechanism commonly underlies incomplete dominance but is not a feature of codominance?
Haploinsufficiency where one functional allele does not produce enough product for the full phenotype
Overdominance causing heterozygote advantage
Expression of two distinct antigens equally on a cell surface
Allelic exclusion leading to monoallelic expression
Incomplete dominance often results from haploinsufficiency, where a single functional copy of a gene produces insufficient product, yielding an intermediate phenotype. In codominance, both alleles produce sufficient, distinct products that are both visible. Haploinsufficiency is therefore characteristic of incomplete dominance but not codominance. source
0
{"name":"What best describes codominance in genetics?", "url":"https://www.quiz-maker.com/QPREVIEW","txt":"What best describes codominance in genetics?, What is the phenotypic outcome of incomplete dominance?, Which of these is a classic example of codominance?","img":"https://www.quiz-maker.com/3012/images/ogquiz.png"}

Study Outcomes

  1. Differentiate codominance vs incomplete dominance -

    Describe how these inheritance patterns vary at both allele and phenotype levels, highlighting key genetic distinctions.

  2. Analyze practice problems for incomplete dominance and codominance -

    Interpret Punnett square - based questions to determine genotypic and phenotypic ratios in non-Mendelian inheritance scenarios.

  3. Predict phenotypic ratios in codominant vs incomplete dominance crosses -

    Use Punnett squares to forecast offspring phenotypes under each dominance pattern, applying genetics principles.

  4. Apply genetic notation and terminology -

    Demonstrate proper use of allele symbols and genetics vocabulary to accurately model codominance and incomplete dominance cases.

  5. Evaluate your solutions with the answer key -

    Compare your answers against the codominance incomplete dominance practice problems answer key to identify and correct errors.

  6. Interpret non-Mendelian inheritance in real examples -

    Assess how codominant and incomplete dominance traits contribute to phenotypic diversity in various organisms.

Cheat Sheet

  1. Defining Codominance vs Incomplete Dominance -

    In incomplete dominance, heterozygotes show an intermediate phenotype (e.g., red × white snapdragons produce pink flowers), while in codominance both alleles are fully expressed side by side (e.g., roan cattle have both red and white hairs). Reviewing this distinction is key to mastering practice problems incomplete dominance and codominance. Sources: NC State University Genetics, Khan Academy.

  2. Predicting Phenotypic Ratios -

    Both codominance and incomplete dominance crosses often yield a 1:2:1 genotypic ratio and a corresponding 1:2:1 phenotypic ratio when only two alleles are involved. For example, crossing two pink snapdragons (Rr) gives 1 red (RR), 2 pink (Rr), 1 white (rr); a similar Punnett square applies to codominant traits like ABO blood types. Refer to University of Arizona's genetics modules for detailed practice codominance and incomplete dominance problems.

  3. Real-World Examples to Remember -

    Snapdragon flower color (incomplete dominance) and human ABO blood groups (codominance) are classic examples you'll see in exams. Memorize that IA and IB alleles coexpress in type AB blood, just like red and white petals coexpress on roan cattle. Verified by research from the American Society for Biochemistry and Molecular Biology.

  4. Punnett Square Strategies -

    Set up a 2×2 grid, label gametes on top and side, then fill in offspring genotypes to solve codominance incomplete dominance practice problems answer key. For incomplete dominance, translate genotypes directly to intermediate phenotypes; for codominance, list both trait symbols (e.g., IAIB). See MIT OpenCourseWare for step-by-step examples.

  5. Mnemonic Tricks for Quick Recall -

    Use "In the Middle" for incomplete dominance (intermediate phenotype) and "Co-Show" for codominance (both traits show). This simple phrase speeds up recall during timed quizzes and practice codominance and incomplete dominance drills. Backed by study tips from the University of Michigan Learning Center.

Make a Quiz (FREE) Copy & Edit This Quiz Create a Quiz with AI

Biology Quizzes

Powered by: Quiz Maker