AP Biology Units 5-8 Comprehensive Review Flashcards

A complete set of vocabulary flashcards covering key concepts from Units 5 through 8 of the AP Biology curriculum, including genetics, molecular biology, evolution, and ecology.

Haploid

A cell containing half the number of chromosomes ($n$) compared to the parent cell, as seen in daughter cells resulting from meiosis.

Diploid

A cell containing two complete sets of chromosomes ($2n$), one from each parent.

Homologous chromosomes

A pair of chromosomes that have the same length, centromere position, and possess genes for the same characters at corresponding loci.

Crossing over

A mechanism during meiosis where nonsister chromatids exchange genetic material, giving rise to genetic variation.

Independent assortment

A Mendel's law stating that genes for different traits can segregate independently during the formation of gametes; applied to genes on different chromosomes.

Nondisjunction

An error in meiosis or mitosis in which members of a pair of homologous chromosomes or sister chromatids fail to separate properly from each other.

Law of segregation

Mendel's law stating that the two alleles for a heritable character separate during gamete formation and end up in different gametes.

Rule of multiplication

A probability law used to determine the chance that two or more independent events will occur together in some specific combination.

Rule of addition

A probability law used to determine the chance that any one of two or more mutually exclusive events will occur.

Phenotypic plasticity

The ability of one genotype to produce more than one phenotype when exposed to different environments.

Plasmids

Small, circular, double-stranded DNA molecules that are distinct from a cell's chromosomal DNA, commonly found in prokaryotes.

Helicase

An enzyme that untwists the double helix of DNA at the replication forks, separating the two strands.

Topoisomerase

An enzyme that helps relieve strain in the double helix ahead of the replication fork by breaking, swiveling, and rejoining DNA strands.

DNA polymerase

An enzyme that catalyzes the synthesis of new DNA by adding nucleotides to the $3'$ end of an existing chain in the $5' \rightarrow 3'$ direction.

Ligase

An enzyme that joins the sugar-phosphate backbones of all the DNA fragments together into a continuous DNA strand.

Antisense strand

Also known as the noncoding, minus, or template strand of DNA, which is read in the $3' \rightarrow 5'$ direction during transcription.

Transcription factors

Regulatory proteins that bind to DNA and affect transcription of specific genes.

Alternative splicing

A eukaryotic process where different mRNA molecules are produced from the same primary transcript, depending on which RNA segments are treated as exons and introns.

Reverse transcriptase

An enzyme used by retroviruses to provide an RNA-to-DNA information flow.

Bacterial transformation

A process that increases genetic variation by the genotype and phenotype alteration of a prokaryotic cell through the uptake of foreign DNA from the surroundings.

Operon

A unit of genetic function found in prokaryotes consisting of a promoter, an operator, and a cluster of genes that are cotranscribed into a polycistronic mRNA.

Epigenetic changes

Reversible modifications to DNA or histones (such as methylation or acetylation) that affect gene expression without altering the DNA sequence.

Polymerase chain reaction (PCR)

A laboratory technique used to amplify a specific segment of DNA to create millions of copies.

Genetic drift

A process in which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next, such as the bottleneck effect or founder effect.

Hardy-Weinberg equation

A mathematical model for a nonevolving population expressed as $p^2 + 2pq + q^2 = 1$, where $p$ and $q$ represent allele frequencies.

Allopatric speciation

The formation of new species in populations that are geographically isolated from one another.

Sympatric speciation

The formation of new species in populations that live in the same geographic area.

Punctuated equilibrium

An evolutionary model where long periods of apparent stasis are interrupted by brief periods of sudden change.

Endotherms

Organisms that use thermal energy generated by metabolism to maintain a homeostatic body temperature.

Ectotherms

Organisms that lack efficient internal mechanisms for maintaining body temperature and rely on environmental heat sources.

Exponential growth

Population growth that occurs under ideal conditions with abundant resources, calculated as $\frac{dN}{dt} = r_{max}N$.

Logistic growth

Population growth that levels off as population size approaches carrying capacity ($K$).

Keystone species

A species that is not necessarily abundant in a community yet exerts strong control on community structure by the nature of its ecological role.