| A | B |
|---|
| ATP | main energy unit within a cell. ATP is produced by photosynthesis or cellular respiration. It consists of an adenosine and three phosphates. |
| anterioir pituitary | Located in the brain. It secretes three growth hormones GH, ACTH, and TSH and three reproductive hormones FSH, LH and Prolactin |
| activiation energy | the amount of energy needed to break chemical bonds before new ones can form. Enzymes lower the activiation energy by bring molecules close together |
| action potential | a change in the membrane that fires a nerve impulse. If a stimulus is sufficient to excite a neuron it creates an action potential. The action potential is 'all or nothing' |
| acoelomates | animals that lack a body cavitiy such as the flatworm. animals that develop a cavity from the mesoderm are coelomates. |
| acetylcholone | a neurotransmitter released between neurons. in the parasynpatetic system, it stimulates muslces to contract |
| annelida | animals lhylum that includes segmented worms. they posses two openings a mouth and anus and have a closed circulatory system |
| alleles | copies of a gene that show some difference from the original. these differences account for different traits within a population |
| anthophyta | phylum of plants that includes flowering plants. they make seeds inclosed in a fruit or nut |
| anitbodies | immune moleucles in the blood that bind and destroy anitgens. produced by a white blood cell known as plasma cells |
| allantois | extraembryoninc membrane found in the eggs of birds, reptiles and mammals. Help in the exchange of gases and stores toxic metabolic wastes like urin acid |
| amnion | extra embryoninc membrane in birds adn repriles and mammals. it protects the embryo in a fluid filled sac |
| ammonia | by product that occurs when cells break down proteins. ammonia is toxic. it is converted into uric acid by birds and reptiles and urea in mammals |
| alveolus | part of the repiratory system when oxygen diffuses in adn carbon dioxide diffuses out |
| altruistic behavior | behaviors that benefit other organisms in the population at the expense of the individiual. for instance meercats warning the troop of danger. |
| adreanl medulla | part of the endocrine system produces the hormones epinephrine (adrenaline) and norepinephrine. these stimulate the fight or flight response |
| allosteric regulators | substances the either inhibit or activate enzymes. inhibitors bind to the active site of a enzyme. activators make the active site available to a substrate |
| amphipatic fatty acids | lipids that have both a hydrophylic and hydrophobic ends |
| anaphase | stage of mitosis in which chromotids are separated |
| analogous structures | features found in two different animlas that have the same function but are structurally different and evolved independently |
