Biology Flashcards: Use Probability For Inheritance Predictions

What this deck covers

This deck focuses on Use Probability For Inheritance Predictions, giving you a quick way to review the definitions, rules, and examples that matter most for Biology.

How to use these flashcards

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 $P(A_{bb})$ in the cross $AaBb \times AaBb$ with independent assortment?

Answer: $\frac{3}{16}$. Dominant for A, recessive for B in dihybrid cross.

Flashcard 2: What is the addition rule for mutually exclusive genetic outcomes?

Answer: $P(A \text{ or } B)=P(A)+P(B)$. Mutually exclusive outcomes add their probabilities.

Flashcard 3: What is the probability an offspring receives allele $A$ from a heterozygous parent $Aa$?

Answer: $\frac{1}{2}$. Equal probability of transmitting either allele.

Flashcard 4: What is the genotype ratio from a monohybrid cross $Aa \times Aa$?

Answer: $1AA:2Aa:1aa$. Classic Mendelian ratio from heterozygous parents.

Flashcard 5: What is $P(A_{bb})$ in the cross $AaBb \times AaBb$ with independent assortment?

Answer: $\frac{3}{16}$. Dominant for A, recessive for B in dihybrid cross.

Flashcard 6: What is $P(aabb)$ in the cross $AaBb \times AaBb$ with independent assortment?

Answer: $\frac{1}{16}$. Recessive phenotype for both traits in dihybrid cross.

Flashcard 7: What is the phenotype ratio with complete dominance from $Aa \times Aa$?

Answer: $3$ dominant : $1$ recessive. Dominant allele masks recessive in heterozygotes.

Flashcard 8: What is $P(aa)$ for the cross $Aa \times Aa$ with complete dominance?

Answer: $\frac{1}{4}$. Only $aa$ shows recessive phenotype in complete dominance.

Flashcard 9: What is $P(Aa)$ for the cross $Aa \times Aa$?

Answer: $\frac{1}{2}$. Heterozygous offspring from two heterozygous parents.

Flashcard 10: What is $P(\text{dominant phenotype})$ for $Aa \times Aa$ with complete dominance?

Answer: $\frac{3}{4}$. Both $AA$ and $Aa$ show dominant phenotype.

Flashcard 11: What is $P(\text{recessive phenotype})$ for the cross $AA \times Aa$?

Answer: $0$. Homozygous dominant parent cannot produce recessive offspring.

Flashcard 12: What is the phenotype ratio for incomplete dominance in the cross $Rr \times Rr$?

Answer: $1$ red : $2$ pink : $1$ white. Heterozygotes show a blended intermediate phenotype.

Flashcard 13: What is $P(\text{intermediate phenotype})$ for incomplete dominance in $Rr \times Rr$?

Answer: $\frac{1}{2}$. Heterozygotes ($Rr$) show the intermediate pink phenotype.

Flashcard 14: What is the phenotype ratio for codominance in the cross $C^RC^W \times C^RC^W$?

Answer: $1$ red : $2$ roan : $1$ white. Both alleles are expressed simultaneously in heterozygotes.

Flashcard 15: What is $P(\text{roan})$ for codominance in $C^RC^W \times C^RC^W$?

Answer: $\frac{1}{2}$. Heterozygotes express both red and white alleles simultaneously.

Flashcard 16: What is the genotype ratio for the ABO cross $I^Ai \times I^Bi$?

Answer: $\frac{1}{4}$ each: $I^AI^B$, $I^Ai$, $I^Bi$, $ii$. Each genotype appears in $\frac{1}{4}$ of offspring.

Flashcard 17: What is $P(\text{type O})$ for the ABO cross $I^Ai \times I^Bi$?

Answer: $\frac{1}{4}$. Only $ii$ genotype produces type O blood.

Flashcard 18: What is $P(\text{type AB})$ for the ABO cross $I^Ai \times I^Bi$?

Answer: $\frac{1}{4}$. Only $I^AI^B$ genotype produces type AB blood.

Flashcard 19: What is the classic dihybrid phenotype ratio from $AaBb \times AaBb$ (independent assortment)?

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

Flashcard 20: What is P(A_B_) in the cross $AaBb \times AaBb$ with independent assortment?

Answer: $\frac{9}{16}$. Dominant phenotype for both traits using independent assortment.

Flashcard 21: What is $P(aaB_)$ in the cross $AaBb \times AaBb$ with independent assortment?

Answer: $\frac{3}{16}$. Recessive for A, dominant for B in dihybrid cross.

Flashcard 22: What is the probability rule that justifies multiplying probabilities across different genes in a dihybrid cross?

Answer: Independent assortment (treat events as independent). Genes on different chromosomes assort independently during meiosis.

Flashcard 23: What is the probability of producing gamete $AB$ from genotype $AaBb$ (independent assortment)?

Answer: $\frac{1}{4}$. Each of four possible gamete types equally likely.

Flashcard 24: What is $P(AAbb)$ in the cross $AaBb \times AaBb$ (independent assortment)?

Answer: $\frac{1}{16}$. Homozygous dominant A, homozygous recessive b.

Flashcard 25: What is $P(\text{dominant for both})$ using the product rule if $P(A_)=\frac{3}{4}$ and $P(B_)=\frac{3}{4}$?

Answer: $\frac{9}{16}$. Multiply independent probabilities: $\frac{3}{4} \times \frac{3}{4}$.

Flashcard 26: What is $P(\text{offspring is heterozygous at both loci } AaBb)$ in $AaBb \times AaBb$?

Answer: $\frac{1}{4}$. Heterozygous at both loci in dihybrid cross.

Flashcard 27: What is $P(\text{at least one recessive phenotype})$ in $Aa \times Aa$?

Answer: $\frac{1}{4}$. Recessive phenotype probability in monohybrid cross.

Flashcard 28: What is $P(\text{not recessive phenotype})$ in $Aa \times Aa$ with complete dominance?

Answer: $\frac{3}{4}$. Complement of recessive phenotype probability.

Flashcard 29: What is $P(\text{both children are } aa)$ if each child has $P(aa)=\frac{1}{4}$ and births are independent?

Answer: $\frac{1}{16}$. Independent events multiply: $\frac{1}{4} \times \frac{1}{4}$.

Flashcard 30: What is $P(\text{at least one } aa)$ in two children if each has $P(aa)=\frac{1}{4}$?

Answer: $1-\left(\frac{3}{4}\right)^2=\frac{7}{16}$. Use complement rule: 1 minus probability of no $aa$ children.