Bio
Terms
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- Spores
- Plant tissue consisting of undifferentiating cells that divide and generate new cells and tissues.
- Prezygotic
- Reproductive barriers that occur before fertilization of an egg (i.e. before the zygote).
- Directional Natural Selection
- Selection that causes a shift in allele frequency such that one more more alleles become more common over time.
- Homologous
- similarity of form among speciees due to common ancestry
- Postzygotic
- Reproductive barriers that stop reproduction after fertilization (i.e. after the zygote forms).
- Organ
- where different tissues are bound together in a structure for one purpose
- Cellular
- where different cell types are specialized to particular functions
- Mutation
- A change in the nucleotide sequence of DNA; the ultimate source of genetic diversity.
- Bottleneck Effect
- Genetic drift resulting from a drastic reduction in population size.
- Vascular Cambium
- A continuous cylinder of meristematic cells surrounding the xylem and pith that produces secondary xylem and phloem
- Exaptations
- A structure that has evolved in one environmental context and later becomes adapted for a different function in a different environmental context.
- Morphological Species Concept
- a classification system based on observable and measurable phenotypic traits
- Monocots
- A subdivision of flowering plants whose members possess one embryonic seed leaf, or cotyledon
- Artificial Selection
- The selective breeding of domesticated plants and animals to enhance particular traits.
- Meristems
- Plant tissue consisting of undifferentiating cells that divide and generate new cells and tissues.
- Gene Pool
- All the genes (alleles) in a population at a given time
- Food Conducting
- Have thin primary walls and no secondary walls, and they remain alive at maturity. Also known as sieve-tube members
- Disruptive Natural Selection
- Selection that favors alleles towards the endpoints of a frequency distribution, but not alleles towards the middle.
- Sexual Selection
- Change in the gene pool due to behavior that causes preferential mating with one or more genotypes.
- Population
- A group of interacting individuals belonging to one species and living in the same geographic area that therefore can potentially interbreed.
- Analogy
- similarity of structure between two species that are not closely related; attributable to convergent evolution
- Stabilizing Natural Selection
- Selection that maintains generally unchanging allele frequencies over time
- Double Fertilization
- A mechanism of fertilization in angiosperms, in which two sperm cells unite with two cells in the embryo sac to form the zygote and endosperm
- Organ System
- where multiple organs coordinate for a particular function
- Pterophytes
- Ferns
- Gradualism
- The view that evolution proceeds by isolated populations gradually becoming genetically unique as they are adapted by natural selection to their local environments. Darwin's view of the origin of species.
- Microevolution
- a change in a population's gene pool over successive generations; evolutionary changes in species over comparably brief periods of time
- Analogous
- similarity of structure between two species that are not closely related; attributable to convergent evolution
- Parenchyma
- A relatively unspecialized plant cell type that carries most of the metabolism, synthesizes and stores organic products, and develops into a more differentiated cell type
- Protobionts
- Collections of abiotically created molecules that direct chemical reactions and are often self-sustaining, and are encapsulated within a membrane.
- Differential Reproductive Success
- offspring that survive to reproduce themselves (see fitness)
- Endoderm
- The innermost of the three primary germ layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract
- Hyphae
- One of many filaments making up the body of a fungus.
- Sympatric Speciation
- The formation of a new species as a result of a genetic change that produces a reproductive barrier between the changed population (mutants) and the parent population. No geographic barrier is present.
- Ribosymes
- RNAs that can also function as enzyme-like catalysts
- Macroevolution
- Evolutionary change on a grand scale, encompassing the origin of new taxonomic groups, evolutionary trends, adaptive radiation and mass extinctions.
- Molecular Biology
- The study of sequence data (nucleotides, peptides) for common biological molecules such as DNA, RNA, and ribosomal proteins and how these sequences differ among species
- Allopatric Speciation
- The formation of a new species as a result of an ancestral population's becoming isolated by a geographic barrier.
- Lateral Meristems
- Cylinder-shaped corers of plant tissue that remain embryonic as long as the plant lives, allowing for indeterminate growth
- Founder Effect
- Random change in the gene pool that occurs from a small starting colony size for a population.
- Cuticle
- In plants, a waxy coating on the surface of stems and leaves that helps retain water.
- Evolutionary Fitness
- The contribution an individual makes to the gene pool of the next generation, relative to the contribution of other members of the population.
- Mycelium
- The entire network of hyphae making up the body of a fungus.
- Radiometric Dating
- A method for determining the age of fossils and rocks from the ratio of a radioactive isotope to the nonradioactive isotope(s) of the same element in the sample.
- Transpiration
- The evaporative loss of water from a plant; typically via the stomata
- Balancing Selection
- Natural selection that maintains stable frequencies of two or more phenotypic forms in a population (balanced polymorphism)
- Collenchyma
- A flexible plant cell type that occurs in strands or cylinders that support young parts of the plant without restraining growth
- Taxa
- (Plural=taxa): A proper name of a group, such as Phylum Chordata, class Mammalia, or Homo sapiens, in the hierarchy or groups used to classify organisms.
- Key Adaptations
- An adaptation that allows a taxon to colonize a new ecological niche and radiate new species, thus defining a larger group
- Tissue
- where cells of one or several types work together for common function, and are bound together with specialized junctions and basal lamina
- Homology
- similarity of form among speciees due to common ancestry
- Phloem
- The portion of the vascular system in plants consisting of living cells arranged into elongated tubes that transport sugar and other organic nutrients throughout the plant
- Acoelomates
- have no internal body space, and must have spongy mesoderm that allows circulation
- Gametangia
- A reproductive organ that houses and protects the gametes of a plant
- Fossil Record
- The fossil species that have been found and their ordered array within layers of sedimentary rock, which provides evidence for the time periods in which those species existed.
- Gene Flow
- The gain or loss of alleles from a population by the movement of individuals into our out of a population.
- Thermophiles
- Organisms that are found in conditions hot enough that most organisms cannot tolerate them.
- Vascular Tissue
- A system formed by xylem and phloem of a plant, serving as a transport system for water and nutrients, respectively.
- Lichens
- A mutualistic association between a fungus and alga or cyanobacterium.
- Natural Selection
- reproductive success is unequal, and those individuals best meeting demands of the environment have the greatest reproductive success
- Binomial
- A system in which each element has two parts, for example the Linnean classification system, where each species has a genus name and specific epithet (e.g. Homo sapiens).
- Turgor
- The normal distension or rigidity of plant cells, resulting from the pressure exerted from within against cell walls by the cell contents
- Biological Species Concept
- a species concept defining a species as a population or group thereof whose members potentially interbreed and produce fertile offspring
- Heterokaryotic
- A life stage of fungi in which cells have two separate haploid nuclei of different parental lineages that have not yet fused.
- Blastula
- The hollow ball of cells marking the end stage of cleavage during early embryonic development
- Ectoderm
- The outermost of the three primary germ layers in animal embryos; gives rise to the outer covering and, in some phyla, the nervous system, inner ear, and lens of the eye
- Dicots
- A subdivision of flowering plants whose members possess two embryonic seed leaves, or cotyledons
- Blastopore
- The opening of the archenteron in the gastrula that develops into the mouth in protostomes and the anus in deuterostomes
- Schlerynchyma
- A rigid, supportive plant cell type usually lacking protoplasts and possessing thick secondary walls strengthened by lignin at maturity
- Pseudocoelom
- A body cavity that is not completely lined by tissue derived from mesoderm
- Predation
- An interaction between species in which one species, the predator, eats the other, the prey
- Paedomorpohosis
- The retention of juvenile features in the adult.
- Water Conducting
- Composed of tracheids and vessel elements, these both have rigid, lignin-containing secondary cell walls
- Cation Exchange
- A process in which positively charged minerals are made available to a plant when hydrogen ions in the soil displace mineral ions from the clay particles
- Gymnosperms
- Conifers
- Bryophytes
- Mosses
- Modern Synthesis
- A comprehensive theory of evolution that incorporates genetics and includes most of Darwin's ideas, focusing on populations as the fundamental units of evolution
- Xylem
- The tube-shaped, nonliving portion of the vascular system in plants that carries water and minerals from the roots to the rest of the plant
- Endospores
- Specially produced internal daughter cells of some bacteria. These are dehydrated, inactive metabolically and protected by a thick outer coat in order to survive adverse environmental conditions, but can rehydrate and begin functioning when conditions have improved.
- Casparian Strip
- A water-impermeable ring of wax around endodermal cells in plants that blocks the passive flow of water and solutes into the stele by way of cell walls
- Zygote
- The diploid product of the union of haploid gametes in conception; a fertilized egg
- Genetic Drift
- A change in the gene pool of a population due to chance.
- Heartwood
- Located in the center portion of a tree trunk, it consists of older layers of secondary xylem
- Gastrula
- The two-layered, cup-shaped embryonic stage
- Cork Cambium
- A cylinder of meristematic tissue in plants that produces cork cells to replace the epidermis during secondary growth
- Parasitism
- A symbiotic relationship in which the symbiont (parasite) benefits at the expense of the host by living either within the host (as an endoparasite) or outside the host (as an ectoparasite)
- Parsimony
- In scientific studies, the assumption that the least complicated explanation is probably the correct one.
- Sporangia
- (Plural= Sporangia). A capsule in fungi and plants in which meiosis occurs and haploid spores develop.
- Choanoflagellates
- A colonial protist that likely gave rise to sponges
- Stochastic
- A process in which the next state of the environment is partially but not fully determined by the previous state; i.e. some random elements intrude on otherwise predictable rules.
- Halophiles
- Organisms that are found in conditions saline (salty) enough that most organisms cannot tolerate them.
- Micronutrients
- An element that an organism needs in very small amounts and that functions as a component or cofactor of enzymes. Fe, Cl, Cu, Mn, Zn, Mb
- Coelom
- A body cavity completely lined with mesoderm
- Angiosperms
- Flowering Plants
- Phylogeny
- The evolutionary history of a group of organisms, generally presented as a branching tree structure and assumed to be based on modern methods of investigating taxonomic relationships.
- Deuterostomes
- One of two distinct evolutionary lines of coelomates, consisting of the echinoderms and chordates and characterized by radial, indeterminate cleavage, enterocoelous formation of the coelom, and development of the anus from the blastopore
- Punctuated Equilibrium
- The idea that speciation occurs in spurts followed by long periods of little change.
- Apical Meristem
- Embryonic plant tissue in the tips of roots and in the buds of shoots that supplies cells for the plant to grow in length
- Stomata
- A pore surrounded by guard cells in the epidermis of a leaf. When stomata are open, CO2 enters a leaf and water and O2 exit. A plant conserves water when stomata are closed.
- Protostomes
- A member of one of two distinct evolutionary lines of coelomates, consisting of the annelids, mollusks, and arthropods, and characterized by spiral, determinate cleavage, schizocoelous formation of the coelom, and development of the mouth from the blastopore
- Biogeography
- The study of the geographic distribution of species
- Macronutrients
- A chemical substance that an organism must obtain in relatively large amounts. C, O, H, N, S, P, Ca, K, Mg
- Lignin
- A chemical (biopolymer, like proteins and DNA) that hardens the cell walls of plants and makes them more difficult to penetrate by water.
- Comparative Anatomy
- The comparison of body structures and how they vary among species
- Comparative Embryology
- The comparison of early stages of development
- Mesoderm
- The middle primary germ layer of an early embryo that develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system
- Ascomycetes
- Molds, yeasts, sac fungi
- Population Genetics
- The study of genetic changes in populations; the science of microevolutionary changes in populations.
- Sapwood
- The lighter colored portion of a log that consists of younger secondary xylem that actually conducts water
- Cambrian Explosion
- Event in the fossil record about 540 million years ago where all larger animal groups (Phyla) appear in a relatively short period of time.
- Basidiomycetes
- Club fungi