AP Biology Flashcards: Mendelian Genetics

What this deck covers

This deck focuses on Mendelian Genetics, giving you a quick way to review the definitions, rules, and examples that matter most for AP 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 does a 1:1:1:1 ratio in offspring suggest?

Answer: Test cross with a heterozygous dihybrid. Equal proportions indicate independent assortment of traits.

Flashcard 2: What is a dominant allele?

Answer: An allele expressed in heterozygotes. Only one copy needed for phenotypic expression.

Flashcard 3: What is the expected phenotypic ratio for a cross of heterozygotes?

Answer: 3:1 for a single trait with complete dominance. Standard F2 phenotypic ratio from monohybrid cross.

Flashcard 4: What is the probability of obtaining a recessive phenotype in a monohybrid cross?

Answer: $\frac{1}{4}$. From F1 × F1 cross, recessive appears in $\frac{1}{4}$ offspring.

Flashcard 5: What is a heterozygous genotype?

Answer: Two different alleles for a trait. One allele is different from the other (Aa).

Flashcard 6: What is a carrier in genetics?

Answer: An individual heterozygous for a recessive trait. Has recessive allele but doesn't express the trait.

Flashcard 7: What does a 9:3:3:1 ratio in offspring indicate?

Answer: Dihybrid cross with independent assortment. Classic Mendelian ratio for two independent traits.

Flashcard 8: What is a Punnett square used for?

Answer: Predicting the outcome of a genetic cross. Grid showing all possible gamete combinations from a cross.

Flashcard 9: Define Mendel's law of independent assortment.

Answer: Genes for different traits assort independently. Inheritance of one trait doesn't affect another trait's inheritance.

Flashcard 10: Define incomplete dominance.

Answer: Heterozygote shows an intermediate phenotype. Blended phenotype between two homozygous parents.

Flashcard 11: What is a Punnett square used for?

Answer: Predicting the outcome of a genetic cross. Grid showing all possible gamete combinations from a cross.

Flashcard 12: What is the F2 generation?

Answer: Offspring from interbreeding F1 individuals. Second generation from F1 × F1 cross.

Flashcard 13: What is a heterozygous genotype?

Answer: Two different alleles for a trait. One allele is different from the other (Aa).

Flashcard 14: What is the purpose of a test cross?

Answer: To determine an organism's genotype. Cross with homozygous recessive to reveal unknown genotype.

Flashcard 15: What is the probability of obtaining a recessive phenotype in a monohybrid cross?

Answer: $\frac{1}{4}$. From $F1 \times F1$ cross, recessive appears in $\frac{1}{4}$ offspring.

Flashcard 16: What is the expected genotypic ratio for a cross of heterozygotes?

Answer: 1:2:1 for a single trait with complete dominance. Standard F2 genotypic ratio from monohybrid cross.

Flashcard 17: Identify the F1 generation.

Answer: The first filial generation from a cross. Immediate offspring from parental cross.

Flashcard 18: Define genotype.

Answer: Genetic makeup of an organism. The actual alleles present in an organism.

Flashcard 19: What is the sum rule in genetics?

Answer: Probability of mutually exclusive events is the sum of their probabilities. Add probabilities for either-or scenarios.

Flashcard 20: What is codominance?

Answer: Both alleles are expressed equally. Neither allele is dominant over the other.

Flashcard 21: What is a monohybrid cross?

Answer: A cross examining one trait. Focuses on inheritance patterns of a single characteristic.

Flashcard 22: What does it mean if an individual is homozygous dominant?

Answer: They have two dominant alleles for a trait. Expresses dominant phenotype for that trait.

Flashcard 23: What is an allele?

Answer: A variant form of a gene. Different versions of the same gene at a locus.

Flashcard 24: What is the phenotypic ratio in a dihybrid cross?

Answer: 9:3:3:1 for two independent traits. Classic ratio from F1 × F1 dihybrid cross.

Flashcard 25: What is codominance?

Answer: Both alleles are expressed equally. Neither allele is dominant over the other.

Flashcard 26: Define Mendel's law of independent assortment.

Answer: Genes for different traits assort independently. Inheritance of one trait doesn't affect another trait's inheritance.

Flashcard 27: Which term describes a gene with multiple alleles?

Answer: Multiple allelism. More than two allelic variants exist for one gene.

Flashcard 28: Which term describes a gene with multiple alleles?

Answer: Multiple allelism. More than two allelic variants exist for one gene.

Flashcard 29: What does a 1:1:1:1 ratio in offspring suggest?

Answer: Test cross with a heterozygous dihybrid. Equal proportions indicate independent assortment of traits.

Flashcard 30: Which organism did Mendel use for his experiments?

Answer: Pea plants (Pisum sativum). Ideal model organism with clear, distinct traits.

Flashcard 31: How does a test cross determine genotype?

Answer: By crossing with a homozygous recessive individual. If recessive offspring appear, original was heterozygous.

Flashcard 32: What is the F2 generation?

Answer: Offspring from interbreeding F1 individuals. Second generation from F1 × F1 cross.

Flashcard 33: What is a dihybrid cross?

Answer: A cross examining two traits. Studies inheritance of two different characteristics simultaneously.

Flashcard 34: What does it mean if an individual is homozygous recessive?

Answer: They have two recessive alleles for a trait. Expresses recessive phenotype for that trait.

Flashcard 35: What does a homozygous genotype consist of?

Answer: Two identical alleles for a trait. Both alleles are the same (AA or aa).

Flashcard 36: What is the principle of segregation in Mendelian genetics?

Answer: Alleles separate during gamete formation. Each parent contributes one allele per trait to offspring.

Flashcard 37: What does it mean if an individual is homozygous dominant?

Answer: They have two dominant alleles for a trait. Expresses dominant phenotype for that trait.

Flashcard 38: What is the genotypic ratio in a monohybrid cross?

Answer: 1:2:1 for homozygous dominant, heterozygous, homozygous recessive. Genotype distribution from F1 × F1 monohybrid cross.

Flashcard 39: What is the product rule in genetics?

Answer: Probability of two independent events occurring together is the product of their probabilities. Multiply individual probabilities for combined events.

Flashcard 40: What is pleiotropy?

Answer: One gene influences multiple traits. Single gene affects multiple, seemingly unrelated characteristics.

Flashcard 41: What is the sum rule in genetics?

Answer: Probability of mutually exclusive events is the sum of their probabilities. Add probabilities for either-or scenarios.

Flashcard 42: What does it mean if an individual is homozygous recessive?

Answer: They have two recessive alleles for a trait. Expresses recessive phenotype for that trait.

Flashcard 43: What is a dominant allele?

Answer: An allele expressed in heterozygotes. Only one copy needed for phenotypic expression.

Flashcard 44: What is the expected genotypic ratio for a cross of heterozygotes?

Answer: 1:2:1 for a single trait with complete dominance. Standard F2 genotypic ratio from monohybrid cross.

Flashcard 45: What is the product rule in genetics?

Answer: Probability of two independent events occurring together is the product of their probabilities. Multiply individual probabilities for combined events.

Flashcard 46: What is the probability of obtaining a dominant phenotype in a monohybrid cross?

Answer: $\frac{3}{4}$. From F1 × F1 cross, dominant appears in $\frac{3}{4}$ offspring.

Flashcard 47: Which organism did Mendel use for his experiments?

Answer: Pea plants (Pisum sativum). Ideal model organism with clear, distinct traits.

Flashcard 48: What does a homozygous genotype consist of?

Answer: Two identical alleles for a trait. Both alleles are the same (AA or aa).

Flashcard 49: What is pleiotropy?

Answer: One gene influences multiple traits. Single gene affects multiple, seemingly unrelated characteristics.

Flashcard 50: Identify the F1 generation.

Answer: The first filial generation from a cross. Immediate offspring from parental cross.

Flashcard 51: Define incomplete dominance.

Answer: Heterozygote shows an intermediate phenotype. Blended phenotype between two homozygous parents.

Flashcard 52: What is the probability of obtaining a dominant phenotype in a monohybrid cross?

Answer: $\frac{3}{4}$. From F1 × F1 cross, dominant appears in $\frac{3}{4}$ offspring.

Flashcard 53: What is the principle of segregation in Mendelian genetics?

Answer: Alleles separate during gamete formation. Each parent contributes one allele per trait to offspring.

Flashcard 54: What is a monohybrid cross?

Answer: A cross examining one trait. Focuses on inheritance patterns of a single characteristic.

Flashcard 55: What is a carrier in genetics?

Answer: An individual heterozygous for a recessive trait. Has recessive allele but doesn't express the trait.

Flashcard 56: What does a 9:3:3:1 ratio in offspring indicate?

Answer: Dihybrid cross with independent assortment. Classic Mendelian ratio for two independent traits.

Flashcard 57: What is an allele?

Answer: A variant form of a gene. Different versions of the same gene at a locus.

Flashcard 58: What is the expected phenotypic ratio for a cross of heterozygotes?

Answer: 3:1 for a single trait with complete dominance. Standard F2 phenotypic ratio from monohybrid cross.

Flashcard 59: What is a pedigree chart?

Answer: A diagram showing familial relationships and traits. Traces inheritance patterns through family generations.

Flashcard 60: What is the genotypic ratio in a monohybrid cross?

Answer: 1:2:1 for homozygous dominant, heterozygous, homozygous recessive. Genotype distribution from F1 × F1 monohybrid cross.

Flashcard 61: What is a pedigree chart?

Answer: A diagram showing familial relationships and traits. Traces inheritance patterns through family generations.

Flashcard 62: What is a dihybrid cross?

Answer: A cross examining two traits. Studies inheritance of two different characteristics simultaneously.

Flashcard 63: Define genotype.

Answer: Genetic makeup of an organism. The actual alleles present in an organism.