Stella Struble Honors Biology Final Exam 2025 Review Flashcards

Flashcards covering Cell Division, Genetics, Evolution, Ecology, and related concepts for review.

Mitosis

Cell division resulting in two daughter cells with the same number of chromosomes as the original cell.

Meiosis

Cell division that results in four haploid cells, each with half the number of chromosomes as the original cell.

Role of Mitosis

Growth, repair, cell replacement, and asexual reproduction.

Role of Meiosis in Multicellular Organisms

Passing on half of genes in sexual reproduction to offspring (in gametes) and maintaining genetic diversity.

Interphase

DNA is unwound and replicated.

Prophase

DNA condenses, spindle fibers form, and the nuclear envelope breaks down.

Metaphase

DNA lines up in the middle of the cell.

Anaphase

Sister chromatids split and are pulled to opposite sides of the cell by spindle fibers.

Telophase

One cell with two nuclei, nuclear envelopes reform.

Cytokinesis (after Mitosis)

Cytoplasm splits into two daughter cells, each with 46 chromosomes and 46 chromatids.

Dominant Allele

Allele that overpowers the recessive allele.

Diploid

46 chromosomes (2n).

Haploid

23 chromosomes (n).

Homologous Pairs

Similar chromosomes but from different parents.

Recombinant Chromatids

Sister chromatids swap/exchange DNA, increasing genetic diversity.

Recombinant Chromatids

Chromatids that have crossed over.

Base-Pairing Rules

A=T, C=G (DNA); A=U, C=G (RNA).

Rosalind Franklin's Contribution

Produced the most significant image of DNA with x-ray crystallography.

Watson and Crick's Contribution

Built 3D model and determined that DNA has an antiparallel structure.

Nucleotide

Nitrogenous base (ATCG or AUGC), deoxyribose/ribose sugar, and phosphate group.

Differences Between DNA and RNA

DNA is double-stranded; RNA is single-stranded. DNA stores energy; RNA is a messenger, transcribes amino acids, and helps make up the ribosomes. DNA has ATGC; RNA has AUGC.

Key Players in DNA Replication

DNA Helicase unwinds the DNA helix; DNA Polymerase adds nucleotides in the 5’ -3’ direction.

Semiconservative Replication

Keeps one strand, adds new on the other strand.

Transcription

Forms RNA strand based on the DNA strand.

Initiation (Transcription)

Binding of RNA polymerase and start of transcription.

Elongation (Transcription)

Adds RNA nucleotides, untwists double helix.

Termination (Transcription)

Transcription ends, final product of mRNA.

Translation

Each codon (3 letters) is read as one amino acid; mRNA contains DNA’s message.

tRNA (Transfer RNA)

Transfers amino acids to the growing polypeptide/protein in a ribosome.

rRNA (Ribosomal RNA)

Helps make up a ribosome.

AUG

Start codon (methionine).

Stop Codon

Signals the end of translation.

Human ABO Blood Types

AB is codominant.

Nondisjunction

Failure of chromosomes to separate properly during meiosis.

Human Genome Project

A large international scientific endeavor that aimed to map and sequence the entire human genome.

Darwin’s Theory of Natural Selection: 5 Major Principles

Variations exist, some variations are favorable (adaptation), more offspring are produced than survive, individuals with greater fitness have a higher chance of survival, and populations change over time (descent with modification).

Directional Selection

One of the extremes is most favorable.

Stabilizing Selection

The intermediate is most favorable.

Disruptive Selection

The intermediate is least favorable (both extremes).

Homologous Structures

Related species have similar bones in the same places that evolved to different sizes/shapes and different functions.

Embryological Similarities

Similar embryos indicate that animals were once related and started similarly and evolved to have traits that better suit their environments.

Molecular Similarities

Different animals that evolved from the same ancestors have the same/similar genetic makeup.

Fossil Record

Preserved remains of ancestors show changes over time.

Speciation

Gene pools change so drastically that two groups of organisms can no longer interbreed.

Geographic Isolation

Two populations separated by a geological barrier.

Behavioral Isolation

Different mating behaviors so no desire to mate.

Mechanical Isolation

The reproductive organs of the two groups are too different.

Temporal Isolation

Do not mate at the same timing (season, day/night, year, etc.).

Hybrid Inviability

Baby is too weak and dies in the womb or very young.

Hybrid Sterility

The offspring is sterile.

7 Taxa

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

Binomial Nomenclature

A two-part scientific naming system that uses Latin words, is always in italics, and consists of the genus name and species descriptor.

3 Domains of Life

Bacteria, Archaea, and Eukarya.

Convergent Evolution

When two different organisms/species that are not related but possess similar traits evolved due to living in similar environments.

Levels of Ecological Organization (Smallest to Largest)

Organism, population, community, ecosystem, biome, biosphere.

Organism

Individual living thing.

Population

Group of organisms of the same species in one area.

Community

Group of different populations in the same area.

Ecosystem

The community and nonliving components.

Biome

A major regional or global community of organisms characterized by the climate conditions and plant communities that thrive there.

Biosphere

The global sum of all ecosystems on Earth, encompassing all living organisms and the non-living components they interact with.

Movement of Energy vs. Nutrients

Energy flows in one direction, nutrients recycle.

Abiotic Factors

Nonliving (and NEVER living) factors.

Biotic Factors

Living factors that are also dead and once living: plants, trees, food

Ecological Niche

The role and position of a species in its environment.

Competition

When two organisms fight for the same limited resources.

Predation

Occurs when an organism captures and eats another.

Symbiosis

A close relationship between two or more different species that live in close contact.

Mutualistic Symbiosis

Both organisms benefit from the relationship.

Commensalistic Symbiosis

One organism benefits and one is unharmed.

Parasitic Symbiosis

One organism benefits and one is harmed.

Freshwater Biome

Rivers, lakes, streams, ponds, water does not contain salt; algae, plankton, fish, etc.

Savanna Biome

Type of grassland (tropical); warm year-round; wet and dry seasons; grasses and few trees, large herds of grazing animals.

Freshwater Wetlands Biome

Swamps, marshes, bogs; not saltwater; important as feeding and breeding grounds.

Taiga Biome

Long cold winters, short humid summers; conifers dominate.

Temperate Forest Biome

Seasonal temperature, precipitation evenly spaced, deciduous trees.

Temperate Grassland Biome

Temperate (moderate) climate with 4 seasons, mostly grass and grazing animals.

Tundra Biome

Located near N and S pole, no trees, permafrost, low flora and fauna diversity.

Chaparral Biome

Warm, dry Mediterranean climate, small trees and shrubs, prone to wildfires.

Rainforest Biome

Located near the equator, warm weather year-round, heavy rainfall, thick forests, high flora and fauna diversity.

Desert

High day temperature, low night temperature, very dry climate, flora with water storage, nocturnal fauna.

Exponential Growth

Growing without limitations (UNLIMITED RESOURCES).

Logistic Growth

Population growth levels off.

Carrying Capacity

Maximum number of organisms an environment can support.

Deforestation

Cutting down trees.

Ocean Acidification

More CO2 in atmosphere/ocean → More acidic environment → lower pH.

Biological Magnification

Build up of toxic compounds, hurts animals higher up in a food chain.

Invasive Species

Nonnative species introduced into an environment; harm native species.

Global Warming/Greenhouse Effect

Greenhouse effect is a natural phenomenon that maintains Earth’s temperature range. With higher CO2 concentrations comes the expectation of a stronger greenhouse effect and therefore warmer global temperatures.

Homologous Structures

Related species have similar bones in the same places that evolved to different sizes/shapes and different functions.

Cellular Respiration

Glucose + Oxygen → CO2 + H2O + Energy.

Photosynthesis

Light + CO2 + H2O → Glucose + Oxygen.