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1. Abiotic: Non-living, may be within or made by a living organism.
2. Biotic: Living. Matter is considered ______ if it was ever alive at some point in time
3. Atom: Smallest level. The basic unit of matter. Consists of a dense nucleus surrounded by electrons.
4. Molecule: Second level. A chemical structure consisting of at least two atoms held together by a chemical bond.
5. Macromolecule: Third level. Biologically important molecules that are technically polymers. Example: DNA.
6. Cell: Fourth level. The fundamental unit of life. Essentially a tiny droplet of water and other molecules enclosed by
a fluid "skin" or membrane. The smallest and simplest entity that possesses all the characteristics of life.
7. Organelle: Fifth level. Compartments inside the cell that contain specific groups of macromolecules and carry
out specific cellular functions. One of these organelles is the nucleus; it encloses the DNA within the cell.
8. Microorganism: Sixth level. Single-celled life form. Consists of just one cell and include unicellular organisms
such as bacteria and protists.
9. Tissue: Seventh level. Formed when similar cells work together to fulfill the same detailed function.
10. Organ: Eighth level. Collections of tissues that work together to carry out a common general function. Present
not only in higher level animals but also in plants.
11. Organ System: Ninth level. Consists of functionally related organs. Mammals have many.
12. Organism: Tenth Level. Individual living entities that survive and reproduce as a unit. For example, each tree
in a forest.
13. Population: Eleventh level. Consists of all the individuals of a species living within a specific area.
14. Community: Twelfth level. Populations can interact with each other in positive and negative ways, and
together they form this.
15. Ecosystem: Thirteenth level. Consists of all the living things in a particular area together with the abiotic, or
nonliving, parts of that environment.
16. Biosphere: Fourteenth level. The highest level of organization in living systems. The collection of all ecosystems
on Earth. Includes all habitable zones on the planet, including land, soil, and rocks to a great depth in the Earth's crust;
water and ice; and the atmosphere to a great height.
17. Emergent Properties: Characteristics of a system that are not present in any of its component parts.
18. Biology: The scientific study of life and is the branch of science that studies living organisms and the way
organisms interact with their environments.
19. Homeostasis: The ability or tendency of organisms and cells to maintain stable internal conditions.
20. Nutrient: Any matter an organism needs but cannot make for itself.
21. Energy: The capacity to do work or to make a change in the location, temperature, or structure of matter. Does
not have mass and it does not take up space, but it can be measured in terms of what it does.
, WGU C190 Intro to Biology
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22. Growth: An increase in size.
23. Development: Structure and function change in an orderly way as an organism passes through its life cycle.
An individual's pattern of _______ is partly determined by genetic instructions.
24. Reproduction: Occurs when an individual organism passes on its genetic information to a newly indepen-
dent organism, or offspring.
25. Evolution: A scientific theory that explains how and why life changes over time. Provides the explanation for
why all living organisms share profound similarities, and yet, the life forms on our planet are so incredibly diverse.
26. Natural Selection: Individuals are always a bit different from their parents and from each other, partly
because of changes to their genes. These differences may be helpful or harmful to the individuals that inherit them. In
nature, individuals often have very low odds of surviving to reproduce. Individuals with slightly harmful or even average
characteristics might be less likely to make it, and those with traits that fit in very well with the local habitat will have the
greatest chance to survive and reproduce. This sorting process goes on generation after generation.
27. Atomic Mass: The sum of the number of protons and the number of neutrons. The mass of an atom.
28. Atomic Number: The number of protons in an atom, displayed for each atom in the periodic table.
29. Chemical Bonds: Attractions between atoms that hold atoms and molecules together.
30. Covalent Bonds: Strongest chemical bond. Occurs between atoms of in the same molecule. Electron pairs
are shared, creating a strong bond between atoms.
31. electron: Subatomic particle, located in shells on the outside of the nucleus, has a negative charge and almost
no mass.
32. electronegativity: A measure of the tendency of an atom to attract a bonding pair of electrons. How strongly
does an atoms attract bonding electrons to itself?
33. element: Atoms with unique properties, designated by the atomic number.
34. hydrogen bond: Weak chemical bond. Occurs between atoms in different molecules or parts of molecules.
Weak electrostatic attraction between areas of molecules with opposite partial charges.
35. ion: Positively or negatively charged atom.
36. ionic bond: Moderately strong chemical bond. Occurs between atoms in the same molecule. Electrons transfer
from one atom to another.
37. isotope: Any or two or more forms of a chemical element, having the same number of protons in the nucleus,
or the same atomic number, but having different numbers of neutrons in the nucleus, or different atomic weights.
38. matter: Anything that occupies space and has mass.
39. molecular formula: A formula giving the number of atoms of each of the elements present in one molecule
of a specific compound.