Biology Flashcards: Explain Inheritance Patterns With Evidence

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This deck focuses on Explain Inheritance Patterns With Evidence, giving you a quick way to review the definitions, rules, and examples that matter most for Biology.

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Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: Which cross is a testcross for a dominant-phenotype individual with genotype unknown (A_) ?

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

Flashcard 2: What is the probability that a child from $AaBb \times AaBb$ shows both recessive phenotypes (aabb)?

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

Flashcard 3: What is the definition of genotype in genetics?

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

Flashcard 4: What is the expected phenotypic ratio from a monohybrid cross $Aa \times Aa$ with complete dominance?

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

Flashcard 5: What is the expected genotypic ratio from a monohybrid cross $Aa \times Aa$?

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

Flashcard 6: Which cross is a testcross for a dominant-phenotype individual with genotype unknown (A_) ?

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

Flashcard 7: What offspring phenotypic ratio indicates the tested parent is heterozygous in a testcross $A_ \times aa$?

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

Flashcard 8: What offspring result in a testcross indicates the tested parent is homozygous dominant (AA)?

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

Flashcard 9: What is complete dominance?

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

Flashcard 10: What is incomplete dominance?

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

Flashcard 11: What is codominance?

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

Flashcard 12: What is a multiple-allele gene?

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

Flashcard 13: What is pleiotropy?

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

Flashcard 14: What is polygenic inheritance?

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

Flashcard 15: What is epistasis?

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

Flashcard 16: What is a carrier in human genetics?

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

Flashcard 17: What is the typical inheritance pattern of an autosomal recessive disorder?

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

Flashcard 18: What is the typical inheritance pattern of an autosomal dominant disorder?

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

Flashcard 19: What is the key pedigree clue for X-linked recessive inheritance?

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

Flashcard 20: What is the key pedigree clue for X-linked dominant inheritance?

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

Flashcard 21: What is the key pedigree clue for Y-linked inheritance?

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

Flashcard 22: What is the key pedigree clue for mitochondrial inheritance?

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

Flashcard 23: What is a pedigree used for in genetics?

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

Flashcard 24: What does a filled symbol represent in a pedigree?

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

Flashcard 25: What does a half-shaded symbol represent in a pedigree (typical convention)?

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

Flashcard 26: What is the expected phenotypic ratio from a dihybrid cross $AaBb \times AaBb$ with independent assortment?

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

Flashcard 27: Which probability rule is used to add probabilities of mutually exclusive outcomes?

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

Flashcard 28: Which probability rule is used to multiply probabilities of independent events?

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

Flashcard 29: What is the probability that an $Aa$ parent passes allele $a$ to a child?

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

Flashcard 30: What is the probability that a child from $Aa \times Aa$ is homozygous recessive ($aa$)?

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