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: What is the probability that a child from $AaBb \times AaBb$ is $aabb$ (independent assortment)?

Answer: $\frac{1}{16}$. Product rule: $\frac{1}{4} \times \frac{1}{4} = \frac{1}{16}$.

Flashcard 2: 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 3: 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 4: Identify the inheritance pattern: unaffected parents have an affected child; trait can skip generations.

Answer: Autosomal recessive. Carriers can have affected children.

Flashcard 5: 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 6: What is the probability that a child from $Aa \times Aa$ shows the dominant phenotype (complete dominance)?

Answer: $\frac{3}{4}$. Includes $AA$, $Aa$, and $Aa$ genotypes.

Flashcard 7: What does a filled symbol represent in a pedigree?

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

Flashcard 8: 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 9: What is the law of independent assortment?

Answer: Alleles of different genes assort independently into gametes (if unlinked). This is Mendel's second law for unlinked genes.

Flashcard 10: 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 11: 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 12: 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 13: Identify the inheritance pattern: trait shows continuous variation and bell-shaped distribution in a population.

Answer: Polygenic inheritance. Multiple genes create continuous variation.

Flashcard 14: 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 15: What is pleiotropy?

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

Flashcard 16: Identify the inheritance pattern: only males affected and all sons of an affected father are affected.

Answer: Y-linked. Patrilineal inheritance pattern observed.

Flashcard 17: 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 18: What is the genotype of a homozygous dominant individual for a gene with alleles A and a?

Answer: AA. Both alleles are the same dominant type.

Flashcard 19: 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 20: 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 21: What is the genotype of a heterozygous individual for a gene with alleles A and a?

Answer: Aa. One dominant and one recessive allele.

Flashcard 22: What is a recombinant phenotype in a linkage testcross?

Answer: An offspring phenotype not matching either parental allele combination. Results from crossing over during meiosis.

Flashcard 23: Which probability rule is used to add probabilities of mutually exclusive outcomes?

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

Flashcard 24: Identify the inheritance pattern: trait appears in every generation and affected individuals have an affected parent.

Answer: Autosomal dominant. Vertical inheritance through generations.

Flashcard 25: Which probability rule is used to add probabilities of mutually exclusive outcomes?

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

Flashcard 26: What is codominance?

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

Flashcard 27: What is codominance?

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

Flashcard 28: Identify the inheritance pattern: heterozygotes have intermediate phenotype; ratio from $Rr \times Rr$ is $1:2:1$.

Answer: Incomplete dominance. Blended phenotype indicates incomplete dominance.

Flashcard 29: Identify the inheritance pattern: both alleles fully expressed in heterozygote (for example, AB blood type).

Answer: Codominance. Both alleles expressed simultaneously.

Flashcard 30: 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 31: 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 32: 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 33: What is epistasis?

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

Flashcard 34: Which evidence best supports that two genes are linked rather than independently assorting?

Answer: Parental phenotypes exceed recombinant phenotypes in offspring. Linked genes stay together more often.

Flashcard 35: Identify the inheritance pattern: affected father has no affected sons but all daughters are affected.

Answer: X-linked dominant. X chromosome passes to daughters only.

Flashcard 36: 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 37: What is the probability that a child from $Aa \times aa$ shows the recessive phenotype?

Answer: $\frac{1}{2}$. Only $aa$ offspring show recessive trait.

Flashcard 38: Identify the inheritance pattern: both alleles fully expressed in heterozygote (for example, AB blood type).

Answer: Codominance. Both alleles expressed simultaneously.

Flashcard 39: 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 40: 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 41: Identify the inheritance pattern: affected father has no affected sons but all daughters are affected.

Answer: X-linked dominant. X chromosome passes to daughters only.

Flashcard 42: What is the law of independent assortment?

Answer: Alleles of different genes assort independently into gametes (if unlinked). This is Mendel's second law for unlinked genes.

Flashcard 43: What is the genotype of a heterozygous individual for a gene with alleles A and a?

Answer: Aa. One dominant and one recessive allele.

Flashcard 44: What is the law of segregation in Mendelian genetics?

Answer: Allele pairs separate during gamete formation; each gamete gets one allele. This is Mendel's first law describing meiosis.

Flashcard 45: What is the definition of phenotype in genetics?

Answer: Observable traits produced by genotype and environment. Physical appearance resulting from genotype.

Flashcard 46: 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 47: 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 48: What is complete dominance?

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

Flashcard 49: What is the genotype of a homozygous recessive individual for a gene with alleles A and a?

Answer: aa. Both alleles are the same recessive type.

Flashcard 50: 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 51: 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 52: Which probability rule is used to multiply probabilities of independent events?

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

Flashcard 53: What is incomplete dominance?

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

Flashcard 54: What is the genotype of a homozygous recessive individual for a gene with alleles A and a?

Answer: aa. Both alleles are the same recessive type.

Flashcard 55: 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 56: 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 57: 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 58: Identify the inheritance pattern: one gene affects multiple traits, such as a single mutation causing many symptoms.

Answer: Pleiotropy. One gene affects multiple traits.

Flashcard 59: 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 60: What is the law of segregation in Mendelian genetics?

Answer: Allele pairs separate during gamete formation; each gamete gets one allele. This is Mendel's first law describing meiosis.

Flashcard 61: What does a filled symbol represent in a pedigree?

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

Flashcard 62: 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 63: What is the probability that a child from $Aa \times Aa$ is homozygous recessive ($aa$)?

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

Flashcard 64: 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 65: 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 66: 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 67: 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 68: What is the probability that a child from $Aa \times Aa$ shows the dominant phenotype (complete dominance)?

Answer: $\frac{3}{4}$. Includes $AA$, $Aa$, and $Aa$ genotypes.

Flashcard 69: Identify the inheritance pattern: affected mother passes trait to all children; affected father passes to none.

Answer: Mitochondrial (maternal) inheritance. Cytoplasmic inheritance from egg cell.

Flashcard 70: 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 71: What is the probability that a child from $AaBb \times AaBb$ shows at least one dominant phenotype?

Answer: $\frac{15}{16}$. Complement of both recessive: $1 - \frac{1}{16}$.

Flashcard 72: Which probability rule is used to multiply probabilities of independent events?

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

Flashcard 73: What is the probability that a child from $AaBb \times AaBb$ shows at least one dominant phenotype?

Answer: $\frac{15}{16}$. Complement of both recessive: $1 - \frac{1}{16}$.

Flashcard 74: What is the genotype of a homozygous dominant individual for a gene with alleles A and a?

Answer: AA. Both alleles are the same dominant type.

Flashcard 75: Identify the inheritance pattern: mostly males affected and there is no father-to-son transmission.

Answer: X-linked recessive. Males more affected due to hemizygosity.

Flashcard 76: 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 77: What is complete dominance?

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

Flashcard 78: What is the probability that a child from $AA \times aa$ is heterozygous ($Aa$)?

Answer: $1$ (100%). All offspring are $Aa$ from this cross.

Flashcard 79: What is polygenic inheritance?

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

Flashcard 80: What is the definition of phenotype in genetics?

Answer: Observable traits produced by genotype and environment. Physical appearance resulting from genotype.

Flashcard 81: What is genetic linkage?

Answer: Tendency of nearby genes on the same chromosome to be inherited together. Close genes resist independent assortment.