Final Exam Review

Adaptive Radiation

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

Allopatric Speciation

Speciation that occurs when biological populations become geographically isolated from each other to an extent that prevents or interferes with gene flow.

Alternation of Generations

A life cycle in which there is both a multicellular diploid form (the sporophyte) and a multicellular haploid form (the gametophyte).

Amniotic Egg

An egg that contains a fluid-filled amnion sac, a yolk sac, and an allantois, enabling embryonic development to occur on land.

Analogous Traits

Structures or traits in different species that have similar functions but evolved independently, not from a common ancestor (e.g., wings of birds and insects).

Angiosperms

Flowering plants; vascular plants that have seeds enclosed within an ovary (usually a fruit).

Artificial Selection

The intentional breeding of plants or animals for desired traits by humans.

Ascospores

Spores produced within an ascus by fungi of the division Ascomycota.

Ascomycota

A division of fungi characterized by the production of ascospores in asci.

Bacteriophage

A virus that infects bacteria.

Basidiospores

Spores produced on a basidium by fungi of the division Basidiomycota.

Basidiomycota

A division of fungi characterized by the production of basidiospores on basidia.

Bilateral Symmetry

A type of symmetry where the body can be divided into two roughly equal halves that are mirror images of each other along a central plane.

Biological Fitness

The ability of an organism to survive and reproduce successfully in its environment.

Biological Species Concept

Defines a species as a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring.

Carbon Cycle

The biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth.

Commensalism

A symbiotic relationship where one organism benefits and the other is neither harmed nor benefited.

Competitive Exclusion

The principle that two species competing for the same limiting resources cannot coexist if other ecological factors are constant.

Convergent Evolution

The independent evolution of similar features in species of different lineages.

Cordates

Animals that have a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail at some stage of their development.

Deuterostomes

Animals where the blastopore (the first opening in the developing embryo) develops into the anus, and the mouth develops later.

Diploid

A cell or organism containing two complete sets of chromosomes, one from each parent.

Disruptive Selection

A mode of natural selection in which extreme values for a trait are favored over intermediate values.

Ectotherm

An animal that relies on external environmental sources of heat to maintain its body temperature.

Endodermis

A layer of cells in plant roots surrounding the vascular tissue, regulating water and nutrient movement.

Endosperm

Nutritive tissue surrounding the embryo in seeds of angiosperms, providing food for the developing embryo.

Endotherm

An animal that generates its own internal heat to maintain its body temperature.

Endosymbiotic Theory

The theory that mitochondria and chloroplasts originated as free-living prokaryotes that were engulfed by host cells.

Extinction

The complete disappearance of a species.

Feedback Loop (Negative)

A mechanism where a change in a variable triggers a response that counteracts the initial change, stabilizing the system.

Feedback Loop (Positive)

A mechanism where a change in a variable triggers a response that amplifies the initial change, pushing the system further away from its starting point.

Flagella

Whip-like appendages used for locomotion or moving fluids.

Food Web

A diagram representing the feeding relationships between organisms in an ecosystem.

Gametophyte

The haploid multicellular stage in the alternation of generations life cycle of plants and algae.

Gastrovascular Cavity

A digestive cavity in some invertebrates that has only one opening, serving as both mouth and anus.

Gene Flow

The movement of genes into or out of a population due to the migration of individuals or gametes.

Genetic Drift

Random changes in allele frequencies in a population, especially pronounced in small populations.

Genetic Variation

Differences in DNA among individuals within a population.

Gram Negative Bacteria

Bacteria that do not retain the crystal violet stain in the Gram staining method due to a thin peptidoglycan layer and an outer membrane.

Gram Positive Bacteria

Bacteria that retain the crystal violet stain in the Gram staining method due to a thick peptidoglycan layer.

Gymnosperms

Vascular plants that have seeds unenclosed or 'naked' on the surface of cones.

Haploid

A cell or organism containing a single set of chromosomes.

Heterotherm

An animal that can switch between endothermic and ectothermic strategies or that exhibits significant variations in body temperature (e.g., hibernators).

Homeostasis

The maintenance of a stable internal environment in an organism.

Homologous Traits

Structures or traits in different species that are similar because they were inherited from a common ancestor (e.g., forelimbs of mammals).

Meiosis

A type of cell division that reduces the number of chromosomes by half, producing haploid gametes or spores.

Microphylls

Small leaves with a single, unbranched vein, characteristic of some early land plants like lycophytes.

Mitosis

A type of cell division that results in two genetically identical daughter cells, used for growth and asexual reproduction.

Mutualism

A symbiotic relationship where both organisms benefit.

Natural Selection

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

Negative Feedback System

A regulatory mechanism in which the final output inhibits the initial stimulus.

Net Primary Production

The amount of energy accumulated by producers (plants) that is available to consumers in an ecosystem.

Parasitism

A symbiotic relationship where one organism (the parasite) benefits at the expense of the other organism (the host).

Phylogenetic Classification

The arrangement of organisms into groups based on their evolutionary history and relationships.

Phylogenetic Tree (Cladogram)

A branching diagram showing the inferred evolutionary relationships among biological species.

Postzygotic Isolation

Reproductive isolation mechanisms that act after the formation of a zygote, preventing hybrid offspring from developing or reproducing successfully.

Prezygotic Isolation

Reproductive isolation mechanisms that prevent mating or fertilization from occurring.

Protists

A diverse group of eukaryotic organisms that are not plants, animals, or fungi; often unicellular.

Protostomes

Animals where the blastopore (the first opening in the developing embryo) develops into the mouth, and the anus develops later.

Radial Symmetry

A type of symmetry where the body parts are arranged around a central axis, so that any plane passing through the central axis divides the organism into similar halves (e.g., starfish).

Radioarians

A group of amoeboid protists characterized by intricate silica shells.

Reproductive Isolation

Biological barriers that prevent members of different species from interbreeding and producing viable, fertile offspring.

Spirochetes

A group of distinctive Gram-negative bacteria with a helical shape and internal flagella.

Sporophyte

The diploid multicellular stage in the alternation of generations life cycle of plants and algae.

Sympatric Speciation

Speciation that occurs within the same geographical area, without geographical isolation.

Synapomorphies

Shared, derived characteristics that are unique to a particular clade.

Temporal Speciation

Speciation that occurs due to differences in the timing of reproduction.

Transduction

A process of horizontal gene transfer in bacteria via bacteriophages.

Vascular System (Plants)

Tissues (xylem and phloem) that transport water, minerals, and sugars throughout the plant.

Vestigial Traits

Structures or attributes that have lost some or all of their ancestral function in a given species but have been retained through evolution.

Zygote

A diploid cell formed by the fusion of two haploid gametes (a sperm and an egg).