Non-Mendelian Inheritance | CK-12 Foundation - Free Printable

The image presents three examples of inheritance patterns in traits: codominance and incomplete dominance, using animals, plants, and human characteristics. The goal is to identify which trait in each category shows codominance (marked with a red dot) and which shows incomplete dominance (marked with an orange dot). Let's analyze each column:

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1. Dogs (Dog Coat Color)

- Brown dog – one pure color
- Brown and white spots – both colors are visible separately
- White dog – another pure color

✔ Brown and white spots = Codominance
→ Both brown and white alleles are fully expressed, not blended. This is codominance because both traits appear distinctly.

✘ Brown dog or white dog – These are homozygous forms, not showing blending or co-expression.

So:
- Red dot (Codominance) → Brown and white spots
- Orange dot (Incomplete Dominance) → Not applicable here; no blending observed.

Wait — but the diagram has both red and orange dots under the dog column. That suggests two traits are being evaluated. But only one trait (coat color) is shown.

Let’s reconsider: perhaps we’re supposed to compare brown dog vs. white dog → their offspring show spotted (mixed), so it's codominance.

But there's no intermediate (e.g., light brown) — instead, both colors are present → codominance.

Thus:
- Brown and white spots → Codominance
- No incomplete dominance in dogs

But the diagram has both red and orange dots under the dog column. That implies two traits? Or maybe it's a mistake?

Wait — perhaps the dog column is showing three phenotypes: brown, white, and spotted. So:
- Brown × White → Spotted (not blended, but both colors present) → Codominance

So:
- Spotted dog = Codominance ✔
- There is no intermediate (like tan), so no incomplete dominance

So why is there an orange dot (incomplete dominance)? Maybe it's indicating that one trait is codominant and the other is incomplete? But only one trait is shown.

Possibility: The image may be asking us to assign the correct inheritance type for each set of traits.

Let’s look at all three columns.

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2. Trees (Tree Height)

- Tall tree
- Medium tree
- Short tree

This is classic incomplete dominance:
- Tall × Short → Medium height (intermediate phenotype)
- So, medium tree = result of incomplete dominance

✔ Medium tree → Incomplete dominance

- Tall and short are homozygous
- Medium is heterozygous → blended phenotype

So:
- Red dot (Codominance) → ✘ not applicable
- Orange dot (Incomplete Dominance) → ✔ Medium tree

So the tree column should have:
- Red dot: none (no codominance)
- Orange dot: medium tree

But the diagram has both red and orange dots under trees → again, conflicting.

Wait — maybe the red dot indicates which trait is codominant, and orange dot indicates which is incomplete dominance, and we must choose one per column?

But the labels say:

> Under each column:
> - Red dot: Codominance
> - Orange dot: Incomplete Dominance

So perhaps each column has one example of each, but that doesn't make sense.

Wait — actually, looking closely:

Each column has three images, and two dots below: one red, one orange.

So likely, the task is to determine which trait in each group shows codominance and which shows incomplete dominance, and assign the correct dot.

But only one trait is shown per column.

Alternative interpretation: Perhaps the column represents a trait with multiple phenotypes, and we must decide whether it's codominance or incomplete dominance.

Let’s re-analyze.

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Re-evaluation: Each Column Represents a Single Trait with Three Phenotypes

We need to determine if the trait shows codominance or incomplete dominance based on the phenotypes.

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#### Column 1: Dog Coat Color

Phenotypes:
- Brown
- White
- Brown and white spots

→ When a dog inherits one brown allele and one white allele, it has both colors, not a blend.

➡️ This is codominance (both alleles are fully expressed).

No intermediate (like light brown), so not incomplete dominance.

✔ Codominance → Red dot
✘ Incomplete dominance → Not present

But the diagram shows both dots. Maybe the orange dot is wrong?

Wait — perhaps the orange dot is meant to indicate which one is incomplete dominance, but in this case, none is.

Alternatively, maybe the dog coat is codominant, and the other trait in the same column is incomplete dominance? But only one trait.

Wait — perhaps the column is showing two different traits?

No — each column seems to represent one trait.

Wait — perhaps the three images are different genotypes for the same trait, and we must determine the pattern.

Yes — that makes sense.

So:

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Final Interpretation:

Each column shows three phenotypes of a single trait, representing possible outcomes of crosses between two homozygous parents.

We are to determine whether the middle phenotype results from codominance or incomplete dominance.

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1. Dogs: Coat Color

- Brown (BB)
- White (WW)
- Brown and white spots (BW)

→ BW has both colors, not blended → codominance

✔ Codominance → Red dot
✘ Incomplete dominance → No

But the diagram has both dots — so maybe the orange dot is incorrect? Or perhaps we're supposed to assign the correct dot to the correct trait.

Wait — the dots are labeled, and they are placed under the columns.

But the red dot is next to "Codominance", and orange dot next to "Incomplete Dominance".

So perhaps the task is to match the phenotype in each column to the correct inheritance type.

But how?

Wait — perhaps the images are not all part of the same trait.

Wait — let's read carefully.

Actually, looking at the layout:

Each column has three images and two labels below:
- One red dot → Codominance
- One orange dot → Incomplete Dominance

So the task is to determine which trait in each column shows codominance and which shows incomplete dominance.

But each column has only one trait.

Unless...

Ah! Wait — perhaps each column contains two traits? But no — each column has three images.

Another possibility: The first image is one parent, the third is the other parent, and the middle is the offspring.

But that doesn’t fit.

Wait — perhaps the three images represent different genotypes:

For example:
- Homozygous dominant → brown
- Heterozygous → spotted
- Homozygous recessive → white

Then, spotted = codominance

Similarly:
- Tall tree → TT
- Medium → Tt
- Short → tt

→ Medium is intermediate → incomplete dominance

And for hair:
- Spiked → SS
- Spiked and curly → Sc
- Curly → cc

→ Spiked and curly = both traits expressed → codominance

So now we can see:

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Column 1: Dogs (Coat Color)

- Brown → BB
- White → bb
- Brown and white spots → Bb

→ Both colors visible → Codominance

✔ Codominance → Red dot
✘ Incomplete dominance → No

But the diagram has both dots — so maybe we're supposed to choose which one applies.

But the orange dot is there — maybe it's a mistake?

Wait — perhaps the orange dot is meant to be for the tree, and the red dot for the dog?

But they are under each column.

Wait — look at the labels:

Under each column, there is:
- A red dot → labeled "Codominance"
- An orange dot → labeled "Incomplete Dominance"

But these are not assigned — they are just listed.

So perhaps the task is to click or select which one applies to each column.

But since we can't interact, we must explain.

So let's do that.

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✔ Final Analysis:

#### Column 1: Dogs (Coat Color)
- Brown dog → homozygous
- White dog → homozygous
- Brown and white spots → heterozygous

→ The heterozygote shows both colors clearly → codominance

✔ Codominance → Red dot

✘ Incomplete dominance → Not present (no blending)

So only red dot applies.

But the diagram shows both dots — perhaps it's a design flaw, or we are to identify which one is correct.

#### Column 2: Trees (Height)
- Tall → TT
- Medium → Tt
- Short → tt

→ Heterozygous produces intermediate phenotype (medium) → incomplete dominance

✔ Incomplete dominance → Orange dot

✘ Codominance → No (not both traits visible separately)

#### Column 3: Human Hair
- Spiked hair → SS
- Spiked and curly hair → Sc
- Curly hair → cc

→ Heterozygote shows both traits (spiked and curly) → codominance

✔ Codominance → Red dot

✘ Incomplete dominance → No (not a blend, but both traits present)

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✔ Conclusion:

| Column | Trait | Inheritance Type | Correct Dot |
|--------|-------|------------------|-------------|
| 1 (Dogs) | Coat color | Codominance | Red dot |
| 2 (Trees) | Height | Incomplete dominance | Orange dot |
| 3 (Hair) | Hair type | Codominance | Red dot |

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🔍 Explanation:

- Codominance: Both alleles are fully expressed in the heterozygote.
- Example: Brown and white spots in dogs (both colors visible)
- Example: Spiked and curly hair (both styles present)
- Incomplete dominance: The heterozygote shows an intermediate phenotype (a blend).
- Example: Medium tree (between tall and short)

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🟩 Answer:

- Dog column: Codominance (Red dot)
- Tree column: Incomplete Dominance (Orange dot)
- Hair column: Codominance (Red dot)

So, the red dot should be selected for dogs and hair, and the orange dot for trees.

Even though both dots are shown under each column, only one is correct per column.

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✔ Final Solution:

- Dogs: Codominance → Red dot
- Trees: Incomplete Dominance → Orange dot
- Hair: Codominance → Red dot

This matches biological principles.