Explain Inheritance Patterns With Evidence - Biology

$\frac{1}{16}$. Same calculation as genotype probability.

An organism’s allele combination for one or more genes. The specific alleles an organism carries.

$3:1$. Standard ratio for complete dominance crosses.

$1:2:1$ (AA:Aa:aa). Standard genotype distribution from this cross.

Cross with homozygous recessive: $A_ \times aa$. Tests unknown genotype with known recessive.

$1:1$ dominant:recessive. Equal ratios prove the parent is $Aa$.

All offspring show the dominant phenotype. Confirms parent is $AA$, not $Aa$.

Heterozygote phenotype equals homozygous dominant phenotype. Dominant allele masks recessive expression.

Heterozygote shows an intermediate phenotype between homozygotes. Blending of homozygous phenotypes occurs.

Both alleles are fully expressed in the heterozygote. No blending; both traits show distinctly.

A gene with more than two allele forms in a population. More allelic diversity than simple dominance.

One gene influences multiple phenotypic traits. Single gene affects multiple characteristics.

A trait controlled by multiple genes, often showing continuous variation. Multiple genes contribute to one trait.

One gene masks or modifies the phenotypic effect of another gene. Gene interaction affects final phenotype.

A heterozygote who has a recessive allele but usually no symptoms. Contains recessive allele without expression.

Often skips generations; affected individuals can have unaffected parents. Both parents must be carriers ($Aa$).

Often appears every generation; affected individuals usually have an affected parent. One copy of allele causes expression.

More males affected; no father-to-son transmission. Males have only one X chromosome.

Affected father passes trait to all daughters and no sons. X chromosome from father goes to daughters.

Only males affected; affected father passes trait to all sons. Y chromosome passes father to son only.

Trait is transmitted by affected mothers to all children; fathers do not transmit. Mitochondria inherited maternally in most organisms.

To trace inheritance of a trait through multiple generations. Visual family tree showing trait inheritance.

An affected individual (shows the trait). Solid symbol shows trait expression.

A carrier (heterozygote) for a recessive allele. Indicates hidden recessive allele present.

$9:3:3:1$. Standard ratio for two independent genes.

Sum rule (addition rule). For either/or probability calculations.

Product rule (multiplication rule). For both/and probability calculations.

$\frac{1}{2}$. Each gamete gets one of two alleles.

$\frac{1}{4}$. Product rule: $\frac{1}{2} \times \frac{1}{2} = \frac{1}{4}$.