Middle School Life Science Flashcards: Evidence For Inherited Variation

What this deck covers

This deck focuses on Evidence For Inherited Variation, giving you a quick way to review the definitions, rules, and examples that matter most for Middle School Life Science.

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 an allele in a heredity model?

Answer: A different version of the same gene. Alleles create variation in traits.

Flashcard 2: What is the expected phenotype ratio from a model cross of $Aa \times Aa$ with $A$ dominant?

Answer: $3$ dominant phenotype : $1$ recessive phenotype. $AA$ and $Aa$ both show dominant phenotype.

Flashcard 3: What is a gene in a heredity model?

Answer: A DNA segment that influences a trait. Genes are the basic units of heredity.

Flashcard 4: What does genotype mean in a model of inheritance?

Answer: The allele combination an organism has. Genotype determines genetic makeup.

Flashcard 5: What does phenotype mean in a model of inheritance?

Answer: The observable trait produced by genes and environment. Phenotype results from genes and environment interacting.

Flashcard 6: What does it mean if an allele is dominant in a simple model?

Answer: It is expressed with one copy in a heterozygote. Dominant alleles mask recessive ones.

Flashcard 7: What does it mean if an allele is recessive in a simple model?

Answer: It is expressed only with two copies. Recessive traits need homozygous genotype.

Flashcard 8: Which statement correctly links meiosis to inherited variation in offspring?

Answer: Meiosis shuffles alleles, creating new combinations. Sexual reproduction generates genetic diversity.

Flashcard 9: What is an example of evidence from a model that a trait is polygenic?

Answer: Many phenotypes form a continuous distribution. Bell curve distribution indicates polygenic trait.

Flashcard 10: What is polygenic inheritance in a model of variation?

Answer: A trait controlled by many genes, producing a range. Multiple genes create continuous variation.

Flashcard 11: What inheritance pattern produces both traits at the same time in heterozygotes (for example, red and white hairs together)?

Answer: Codominance. Both alleles fully expressed together.

Flashcard 12: What inheritance pattern produces an intermediate phenotype in heterozygotes (for example, red x white gives pink)?

Answer: Incomplete dominance. Heterozygote shows blended phenotype.

Flashcard 13: Which model result matches a test cross $Aa \times aa$ for genotype ratio?

Answer: $1$ $Aa$ : $1$ $aa$. Test cross reveals 1:1 ratio.

Flashcard 14: Which option is the probability of heterozygous offspring from $Aa \times Aa$?

Answer: $\frac{1}{2}$. Half inherit one of each allele type.

Flashcard 15: Which option is the probability of recessive phenotype from $Aa \times Aa$ (complete dominance)?

Answer: $\frac{1}{4}$. One quarter get two recessive alleles.

Flashcard 16: Which model result matches a cross of $Aa \times Aa$ for phenotype ratio (complete dominance)?

Answer: $3$ dominant : $1$ recessive. Mendel's 3:1 ratio for dominant traits.

Flashcard 17: Which model result matches a cross of $Aa \times Aa$ for genotype ratio?

Answer: $1$ $AA$ : $2$ $Aa$ : $1$ $aa$. Monohybrid cross yields 1:2:1 genotype ratio.

Flashcard 18: What is a Punnett square used for in inheritance models?

Answer: Predicting possible offspring genotypes and phenotypes. Visual tool for predicting genetic crosses.

Flashcard 19: What is the difference between homozygous and heterozygous genotypes?

Answer: Homozygous: same alleles; heterozygous: different alleles. Describes whether alleles match or differ.

Flashcard 20: What is the definition of inherited variation in a population?

Answer: Differences in traits passed from parents to offspring. Genetic variation creates diversity within species.

Flashcard 21: What is the most direct model-based explanation for new inherited variation appearing in a population?

Answer: Mutations create new alleles that can be inherited. DNA changes produce variation passed to offspring.

Flashcard 22: What does a pedigree model help you infer about a trait in a family?

Answer: Likely inheritance pattern (dominant or recessive). Tracks trait inheritance through family generations.

Flashcard 23: Which model-based evidence best supports that variation is inherited rather than caused only by environment?

Answer: Offspring traits correlate with parent traits across generations. Environmental factors alone wouldn't show family patterns.

Flashcard 24: What is the definition of codominance in an inheritance model?

Answer: Both alleles are fully expressed in the heterozygote. Both traits appear together, not blended.

Flashcard 25: Identify the genotypes produced by crossing $Aa \times Aa$ (list all possible offspring genotypes).

Answer: $AA$, $Aa$, and $aa$. Each parent contributes either $A$ or $a$ randomly.

Flashcard 26: What is the definition of incomplete dominance in an inheritance model?

Answer: Heterozygote shows an intermediate phenotype. Blends parental traits instead of showing dominance.

Flashcard 27: Which model outcome best supports that a trait is recessive: $0\%$, $25\%$, $50\%$, or $100\%$ affected from $Aa \times Aa$?

Answer: $25\%$ affected. Only $aa$ offspring show recessive trait ($\frac{1}{4}$ probability).

Flashcard 28: Identify the expected recessive-phenotype fraction from a model cross $Aa \times aa$.

Answer: $\frac{1}{2}$. Half get $Aa$ (dominant), half get $aa$ (recessive).

Flashcard 29: Identify the expected offspring genotypes from a model cross $AA \times aa$.

Answer: All offspring are $Aa$. Each parent contributes one different allele.

Flashcard 30: What is the definition of an allele in an inheritance model?

Answer: An alternative version of a gene for the same trait. Different forms of genes create variation in traits.