Honors Biology Spring 2025 Final Exam Review

Bacteriophage

A virus that infects bacteria.

Autosome

Any chromosome that is not a sex chromosome.

Centromere

The region of a chromosome where the two sister chromatids are joined.

Chromosome

A structure made of DNA and proteins that contains genetic information.

Chromosome number

The total number of chromosomes in a cell.

Diploid

A cell that contains two complete sets of chromosomes, one from each parent.

Histone

A protein that helps package DNA into a compact, organized structure.

Karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

Trisomy

A genetic condition where an individual has three copies of a chromosome instead of two.

Monosomy

A genetic condition where an individual has only one copy of a chromosome instead of two.

Nucleosome

A structural unit of a eukaryotic chromosome, consisting of a length of DNA wrapped around a core of histone proteins.

Sex chromosomes

Chromosomes that determine the sex of an individual.

Sister chromatids

Identical copies of a chromosome that are connected by a centromere.

DNA ligase

An enzyme that facilitates the joining of DNA strands together by catalyzing the formation of a phosphodiester bond.

DNA polymerase

An enzyme that synthesizes new DNA strands by adding nucleotides to a pre-existing chain.

DNA replication

The process by which a cell duplicates its DNA before cell division.

Primer

A short strand of RNA or DNA that serves as a starting point for DNA synthesis.

Semiconservative replication

The method of DNA replication in which each new DNA molecule consists of one original strand and one new strand.

Mutation

A change in the DNA sequence that can lead to changes in the structure and function of proteins.

DNA sequence

The order of nucleotides in a DNA molecule.

Nucleotide

The basic building block of DNA and RNA, consisting of a sugar, a phosphate group, and a nitrogenous base.

Haploid

A cell that contains only one complete set of chromosomes.

Messenger RNA

A type of RNA that carries genetic information from DNA to the ribosome for protein synthesis.

Transfer RNA

A type of RNA that helps decode a messenger RNA sequence into a protein.

Ribosomal RNA

A type of RNA that, together with proteins, makes up the ribosome.

Transcription

The process of copying a segment of DNA into RNA.

Translation

The process by which a protein is synthesized from the information contained in a messenger RNA molecule.

Genetic code

The set of rules by which information encoded in genetic material is translated into proteins.

Codon

A sequence of three nucleotides in mRNA that corresponds to a specific amino acid.

Anticodon

A sequence of three nucleotides in tRNA that is complementary to a codon in mRNA.

Promoter

A region of DNA that initiates transcription of a particular gene.

RNA polymerase

An enzyme that synthesizes RNA from a DNA template.

Introns

Non-coding segments of RNA that are removed during RNA processing.

Exons

Coding segments of RNA that are retained and expressed after RNA processing.

Substitution

A type of mutation where one nucleotide is replaced by another.

Insertion

A type of mutation where one or more nucleotides are added to the DNA sequence.

Deletion

A type of mutation where one or more nucleotides are removed from the DNA sequence.

Gene expression

The process by which information from a gene is used to synthesize a functional gene product, usually a protein.

Alleles

Different versions of a gene that may produce distinguishable phenotypic effects.

Sexual Reproduction

The process by which offspring are produced through the combination of genetic material from two parents.

Gametes

Reproductive cells (sperm and eggs) that carry half the genetic information of an organism.

Crossing over

The exchange of genetic material between homologous chromosomes during meiosis.

Meiosis

A type of cell division that reduces the chromosome number by half, producing four haploid cells.

Segregation

The separation of alleles during gamete formation.

Germ cells

Reproductive cells that give rise to gametes.

Fertilization

The fusion of male and female gametes to form a zygote.

Zygote

The fertilized egg that results from the union of sperm and egg.

Tetrads

Structures formed during meiosis consisting of four chromatids that come together during crossing over.

Genotype

The genetic constitution of an individual organism.

Phenotype

The observable physical or biochemical characteristics of an organism, as determined by both genetic makeup and environmental influences.

Homozygous

Having two identical alleles for a particular gene.

Heterozygous

Having two different alleles for a particular gene.

Monohybrid cross

A genetic cross between parents that differ in a single trait.

Dihybrid cross

A genetic cross between parents that differ in two traits.

Test cross

A cross between an individual with an unknown genotype and a homozygous recessive individual.

Purebred

An organism that is the offspring of many generations that have the same traits.

Hybrid

The offspring of two different varieties or species.

Linkage group

A group of genes that are inherited together due to their location on the same chromosome.

Law of independent assortment

The principle that genes for different traits are inherited independently of each other.

Incomplete dominance

A genetic situation in which one allele does not completely dominate another allele, resulting in a new phenotype.

Codominance

A genetic scenario where both alleles in a heterozygote are fully expressed.

Multiple alleles

The presence of more than two alleles for a genetic trait.

Polygenic (epistasis)

A trait controlled by multiple genes, where one gene can mask the expression of another.

Pleiotropic

A single gene that influences multiple phenotypic traits.

Gene

A segment of DNA that contains the instructions for building a protein.

Pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

Carriers

Individuals who carry one copy of a recessive allele that does not manifest in their phenotype.

Single gene trait

A trait that is controlled by a single gene.

Genetic disorder

A disease caused by abnormalities in an individual's DNA.

Genetic abnormality

A deviation from the normal genetic structure, which can lead to disorders.

Natural Selection

The process where organisms better adapted to their environment tend to survive and produce more offspring.

Artificial Selection

The intentional breeding of plants or animals for desired traits.

Homologous Structures

Anatomical features in different species that share a common ancestry.

Vestigial Structures

Body parts that have lost their original function through evolution.

Variation

Differences in physical traits of an individual from the group to which it belongs.

Survival of the Fittest

The concept that individuals best adapted to their environment are more likely to survive and reproduce.

Struggle for Existence

The competition between living things to survive in an environment with limited resources.

Gene Pool

The total collection of genes in a population at any one time.

Relative Frequency

The ratio of a particular allele to the total number of alleles for that gene in a population.

Single-gene Trait

A trait controlled by a single gene.

Polygenic Trait

A trait that is controlled by two or more genes.

Reproductive isolation

A condition that prevents members of different species from producing offspring.

Behavioral isolation

A form of reproductive isolation where two populations develop differences in courtship rituals or other behaviors.

Geographical isolation

A form of reproductive isolation that occurs when populations are separated by physical barriers.

Temporal isolation

A form of reproductive isolation where two species breed at different times.

Directional Selection

A type of natural selection that favors one extreme phenotype.

Stabilizing Selection

A type of natural selection that favors intermediate variants by acting against extreme phenotypes.

Disruptive Selection

A type of natural selection that favors extreme phenotypes over intermediate phenotypes.

Adaptive Radiation

The diversification of a group of organisms into forms filling different ecological niches.

Convergent Evolution

The process where organisms not closely related independently evolve similar traits.

Co-evolution

The influence of closely associated species on each other in their evolution.

Neuron

A nerve cell that transmits impulses; includes parts such as cell body, dendrite, nucleus, axon, myelin sheath, and axon terminal.

Reflex Arc

The neural pathway that controls a reflex action, including sensory neurons, motor neurons, and interneurons.

Sensory Neurons

Neurons that carry signals from sensory organs to the central nervous system.

Motor Neurons

Neurons that transmit signals from the central nervous system to muscles or glands.

Interneurons

Neurons that connect sensory and motor neurons within the central nervous system.

Brain

The organ responsible for processing sensory information, controlling motor functions, and coordinating behavior.

Spinal Cord

The part of the central nervous system that transmits signals between the brain and the rest of the body.

Cerebrum

The largest part of the brain, responsible for higher brain functions such as thought and action.

Brain Stem

The part of the brain that controls basic life functions such as breathing and heart rate.