AP Biology Final Exam Preparation: Vocabulary

Vocabulary-style flashcards covering key topics from Units 5 through 8 of the AP Biology curriculum, including inheritance, gene expression, evolution, and ecology.

Crossing over

The process occurring during Prophase I when homologous chromosomes exchange DNA, creating new combinations of alleles.

Independent assortment

The random alignment of homologous chromosome pairs during Metaphase I, resulting in different combinations of maternal and paternal chromosomes in gametes.

Random fertilization

A source of genetic variation where any sperm can fertilize any egg, producing unique offspring.

Meiosis I Nondisjunction

A failure of homologous chromosomes to separate, usually resulting in four abnormal gametes.

Meiosis II Nondisjunction

A failure of sister chromatids to separate, usually resulting in $2$ normal gametes and $2$ abnormal gametes.

X-linked recessive

An inheritance pattern where a trait appears mostly in males and can skip generations; males express the trait with only one copy of the recessive allele.

Linked genes

Genes located close together on the same chromosome that are usually inherited together and do not follow typical Mendelian ratios.

Monohybrid Cross Phenotype Ratio

The expected ratio of traits from an $Aa \times Aa$ cross, which is $3$ dominant : $1$ recessive.

Dihybrid Cross Phenotype Ratio

The expected ratio from an $AaBb \times AaBb$ cross, expressed as $9:3:3:1$.

Frameshift mutation

A mutation caused by insertions or deletions (not in multiples of three) that changes the reading frame and alters every amino acid after the mutation point.

Lac operon

A prokaryotic gene regulation system that is turned on when lactose binds to a repressor protein, preventing it from binding to the operator.

Epigenetic changes

Factors that affect how genes are expressed and can change phenotype without altering the actual DNA sequence.

DNA methylation

An example of an epigenetic change that can reduce gene expression.

PCR

A biotechnology tool used to produce many copies of a specific DNA sequence.

Gel electrophoresis

A method used to separate DNA fragments by size, where smaller fragments move farther through the gel.

Transcription

The process in which a DNA template strand is used to synthesize an mRNA strand.

Translation

The process in which mRNA is used to build a protein by reading codons in groups of three bases.

Codon

A group of three mRNA bases that codes for one specific amino acid.

Antibiotic resistance

The evolution of a bacterial population where resistant individuals survive antibiotic exposure and pass on resistance alleles.

Bottleneck event

An event that greatly reduces population size, leading to the loss of alleles and a decrease in genetic diversity.

Gene flow

The movement of alleles between populations, typically occurring through migration.

Genetic drift

A random change in allele frequencies that has a more significant impact on small populations.

Reproductive isolation

A mechanism that prevents populations from interbreeding, potentially leading to speciation.

Speciation

The formation of new species as isolated populations accumulate different mutations and adaptations over time.

$$p$$

In Hardy-Weinberg equilibrium, this variable represents the frequency of the dominant allele.

$$q$$

In Hardy-Weinberg equilibrium, this variable represents the frequency of the recessive allele.

$$p^2$$

In Hardy-Weinberg equilibrium, this represents the frequency of homozygous dominant individuals.

$$q^2$$

In Hardy-Weinberg equilibrium, this represents the frequency of homozygous recessive individuals.

$$2pq$$

In Hardy-Weinberg equilibrium, this represents the frequency of heterozygous individuals.

Invasive species

Non-native species that can outcompete native species and often lack natural predators, altering food webs and reducing biodiversity.

Exponential growth

Rapid population growth characterized by a J-shaped curve, occurring when resources are unlimited.

Logistic growth

Population growth that creates an S-shaped curve as the growth rate slows near the carrying capacity due to limited resources.

Carrying capacity

The maximum population size that an environment can support based on available resources.

Keystone species

A species that has a disproportionately large effect on ecosystem structure and maintains biodiversity.