ABIOTIC FACTORS: Non-living things that can affect organisms. Examples: light, temperature, rocks and water
ABSOLUTE AGE: the approximate age of the rock of fossil in years; the absolute age is determined using absolute dating
ABSOLUTE (RADIOMETRIC) DATING: When scientists use radioactive atoms to determine the absolute age of a rock or fossil. The absolute age is how old an object is independent of other objects.
ABUNDANT: a lot; present in great amounts
ACID: A substance with a pH less than 7
ACTIVATION ENERGY: The energy needed to get a reaction started. The speed bump of a chemical reaction. The smaller the activation energy, the faster a reaction can happen. Enzymes speed up reactions by lowering activation energy.
ACTIVE TRANSPORT: A form of transport that moves substances from a region of low concentration to a region of high concentration. This form of transport requires energy (ATP). We can also say that active transport move substances against the concentration gradient. Active transport is like trying to swim AGAINST the current.
ADAPTATION: A random mutation in the DNA leading to a phenotypic change that helps the organism survive and reproduce.
ADAPTIVE RADIATION: Divergent evolution in which an ancestral species evolves into an array of species to fit a number of diverse habitats. Example: Darwin's finches
ADENINE: A nitrogen base found in DNA and RNA nucleotides. Adenine only pairs with thymine in DNA. Adenine only pairs with uracil in RNA.
ADHESION: A property of water that refers to water's ability to stick to other substances.
AEROBIC: uses oxygen
AGENT: The pathogen that causes the disease. For example, the agent of malaria is a parasitic protist.
ALCOHOLIC FERMENTATION: An anaerobic process that causes cells to produce ethyl alcohol (ethanol) as a byproduct of cellular respiration happening in the absence of oxygen. Bacteria and yeast participate in alcoholic fermentation. We use these organisms to produce beer, wine and cheeses.
ALGAE: A photosynthetic, plant-like, autotrophic protist.
ALLELE: Represented by either a capital or lowercase letter, alleles are alternate versions of genes. An allele can either by dominant or recessive.
ALKALI METAL: Group IA of the periodic table (not including Hydrogen). 1 valence electron. VERY high reactivity.
ALKALINE EARTH METALS: Group IIA of the periodic table. 2 valence electrons. High Reactivity.
AMINO ACID: The monomer (building block) of a protein
AMYLASE: A digestive enzyme found in saliva that breaks down carbohydrates (sugars)
ANAEROBIC: Does not use oxygen
ANALOGOUS STRUCTURES: Structures that do not have a common evolutionary origin but are similar in function. Analogous structures form because of environmental pressures. Analogous structures are evidence of convergent evolution. An example of analogous structures would be a fish fin and a whale fin.
ANAPHASE: The third phase of mitosis, where chromosomes are split. The separated sister chromatids move to opposite ends of the cell.
ANIMALS (ANIMALIA): One of the six kingdoms of life. Animals are multicellular, heterotrophic eukaryotes. Examples of animals are humans, insects, sponges and fish.
ANTIBIOTIC: Substances produced by microorganisms that disrupt bacterial metabolism, killing the bacterium.
AQUIFER: An underground area of water storage.
ARCHAEBACTERIA: One of the six kingdoms of life, this kingdom contains prokaryotic, unicellular organisms that are found in very harsh environments where there is an absence of other life. Archaebacteria are known as extremophiles because of their ability to survive in uniquely harsh environments.
ARTIFICIAL SELECTION: A process of breeding organisms with specific traits in order to produce offspring with identical traits. Example: selectively breeding dogs to develop unique characteristics like a chihuahua or great dane
ASEXUAL REPRODUCTION: Reproduction that requires only one parent. All offspring (babies) are identical to the parent and are created by mitosis. This form of reproduction makes clones.
ATP (Adenosine Triphosphate): The molecule of energy for the cell that is made during the process of cellular respiration.
ATOMIC MASS: Atomic mass is equal to the number of protons plus the number of neutrons.
ATOMIC NUMBER: An element's atomic number is equal to the number of protons.
AUTOSOMES: The first 22 pairs of homologous chromosomes in a somatic cell. Autosomes do not control the sex of an organism.
AUTOTROPH: An organism that makes it own food through the process of photosynthesis.