Chapter 1.txt

  1. Animals
    Any multicelled heterotroph that ingests other organisms or their tissues, develops through a series of embryonic stages, and is motile during part or all of the life cyle. Most species have epithelial tissues and extracellular matrixes.
  2. Archaea
    Domain of prokaryotic species; one of two lineages that evolved shortly after life originated. Archaeans have many unique molecular and biochemical traits but also share some traits with bacteria and other traits with eukaryotic species.
  3. Artificial selection
    Manipulation of the reproduction of a species as by breeding practices. Only individuals of a captive population that display a valued trait are allowed to reproduce, the goal being to increase the trait�s magnitude and frequency over the generations.
  4. Bacteria
    Domain of prokaryotic species; the first kinds of cells that formed after life originated. Collectively, bacteria are the most metabolically diverse organisms. Most kinds are chemoheterotrophs.
  5. Biosphere
    [Gk. bios, life, + sphaira, globe] All regions of Earth�s waters, crust, and atmosphere in which organisms live.
  6. Cell
    Smallest unit that still displays the properties of life; it has the capacity to survive and reproduce on its own.
  7. Community
    All populations of all species in a habitat.
  8. Consumers
    Type of heterotroph that feeds on the tissues of other organisms as its source of carbon and energy.
  9. Control group
    In experimental tests, a group used as a standard for comparison against one or more experimental groups.
  10. Decomposers
    [L. dis�, to pieces] One of the prokaryotic or fungal heterotrophs that obtains carbon and energy by breaking down wastes or remains of organisms. The collective action of decomposers helps cycle nutrients to producers in ecosystems.
  11. Development
    Of complex multicelled species, a series of stages from formation of gametes, then fertilization, and on through embryonic and adult forms.
  12. DNA
    Deoxyribonucleic acid. Double-stranded nucleic acid twisted into a helical shape; its base sequence encodes the primary hereditary information for all living organisms and many viruses.
  13. Ecosystem
    Array of organisms, together with their environment, interacting by a flow of energy and cycling of materials.
  14. Emergent properties
    With respect to life�s levels of organization, a new property that emerges through interactions of entities at lower levels, none of which displays the property; e.g., living cells that emerge from �lifeless� molecules.
  15. Energy
    A capacity to do work.
  16. Enzymes
    A type of protein that catalyzes (speeds) a chemical reaction. Some RNAs also show catalytic activity.
  17. Eukarya
    Domain of eukaryotic species; all �protists,� plants, fungi, and animals.
  18. Evolution
    [L. evolutio, an unrolling] Genetic change in a line of descent by microevolutionary events (gene mutation, natural selection, genetic drift, and gene flow); basis of large-scale patterns, rates, and trends in the history of life.
  19. Experimental group
    A group of objects or individuals that display or are exposed to the variable under investigation. Test results for this group are compared against the results for a control group.
  20. Experiments
    A test that simplifies observation in nature or the laboratory by manipulating and controlling conditions under which observations are made.
  21. Fungi
    Kingdom of fungi.
  22. Genus, genera
    [L. genus, race or origin] A grouping of species more closely related to one another in morphology, ecology, and history than to others at the same taxonomic level.
  23. Homeostasis
    [Gk. homo, same, + stasis, standing] State in which physical and chemical aspects of internal environment (blood, interstitial fluid) are being maintained within ranges that are tolerable for cell activities.
  24. Hypothesis
    An explanation of a phenomenon, one that has the potential to be proven false by experimental tests.
  25. Inheritance
    Transmission, from parents to offspring, of genes that underlie the traits characteristic of their species.
  26. Mimicry
    A case of one species (the mimic) closely resembling another (its model) in form, behavior, or both.
  27. Models
    Theoretical explanation of any object or event that has not been or cannot be directly observed.
  28. Mutation
    [L. mutatus, a change, + -ion, act, result, or process] Heritable change in DNA�s molecular structure. Original source of new alleles and life�s diversity.
  29. Natural selection
    Microevolutionary process; the outcome of differences in survival and reproduction among individuals of a population that differ in the details of their heritable traits.
  30. Organ systems
    A set of organs that are interacting chemically, physically, or both in a common task.
  31. Organs
    Body structure with definite form and function made of more than one tissue.
  32. Plants
    A multicelled photoautotroph, most with well-developed roots and shoots (e.g., stems, leaves), as well as photosynthetic cells that include starch grains as well as chlorophylls a and b, and polysaccharides such as cellulose, pectin, and lignin in cell walls. The primary producers on land.
  33. Prediction
    A statement, based on a hypothesis, about what you expect to observe in nature; the �if-then process.�
  34. Producers
    An autotrophic organism.
  35. Prokaryotic
    [L. pro, before, + Gk. karyon, kernel] A single-celled organism, often walled, that does not have the organelles characteristic of eukaryotic cells. Only bacteria and archaeans are prokaryotic.
  36. Protists
    Informal name for all structurally simple eukaryotes, which are now being classified as monophyletic groups.
  37. Receptors
    Sensory cell or a specialized ending of one that detects a particular kind of stimulus.
  38. Reproduction
    Any asexual or sexual process by which a parent cell or organism produces offspring.
  39. Scientific theory
    A time-tested, widely accepted intellectual framework used to interpret a broad range of observations and data about some aspect of nature. Tested rigorously but is still open to tests, revision, and tentative acceptance or rejection.
  40. Species
    [L. species, a kind] Of sexually reproducing species, one or more natural populations of individuals that successfully interbreed and are isolated reproductively from other such groups. By a cladistic definition, one or more natural populations of individuals with at least one unique trait derived a common ancestor that occurs in no other groups.
  41. Stimulus
    [L. stimulus, goad] A specific form of energy that activates a sensory receptor able to detect it; e.g., pressure.
  42. Test
    Any standardized or innovative means by which a prediction based on a hypothesis might be disproved; often requires designing and conducting experiments, making observations, or developing models.
  43. Tissues
    Of multicelled organisms, a group of cells and matrixes interacting in the performance of one or more tasks.
  44. Variable
    Of experimental tests, a specific aspect of an object or event of interest that may differ over time and among individuals. A single variable is directly manipulated in an experimental group.
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Chapter 1.txt
Chapter 1