| acquired characteristic |
a change in the structure or function of a living organism that is caused by environmental factors and may not be transmitted genetically. |
| adaptation |
in biology, the process of change in an organism, over time, resulting in it being better able to survive and multiply. [1/4 definitions] |
| aerobe |
an organism, such as a bacterium, that needs oxygen to live. |
| air chamber |
a compartment in which air is confined for a special use, as in a pump, a hydraulic fluid regulator, or a living organism. |
| air sac |
an air-filled space or cavity in a living organism, esp. any of the ends of certain bronchial tubes in a bird's body that connect with the larger body cavity and assist in breathing. |
| ala |
a wing or winglike part or structure on a living organism. |
| allometry |
the growth rate of part of an organism in comparison with the growth rate of the entire organism or some other part of it. [1/2 definitions] |
| amoeba |
a one-celled organism that changes its shape as it moves and engulfs food. |
| amphioxus |
a tiny fishlike marine organism characterized by a primitive vertebra and dorsal nerve tissue; lancelet. |
| anatomy |
the structure of an organism or of its parts. [2/4 definitions] |
| ancestor |
in biology, an organism or species from which present life forms have evolved. [1/4 definitions] |
| armature |
any part of an organism that provides its defense or offense, esp. an armor-like covering. [1/4 definitions] |
| assimilation |
in biology, the process by which foods or nutrients taken into the organism are transformed into living tissue. [1/3 definitions] |
| atavism |
the reappearance of a biological characteristic in an organism after it has not appeared for several generations, or an organism displaying such a characteristic. [1/2 definitions] |
| atavistic |
of a trait, behavior, or the like, existing or playing a role at an earlier stage or time and recurring or reappearing within an organism or within a society after long absence or seeming disappearance. |
| autonomous |
free and independent, as a state or an organism; self-governing. |
| basal metabolism |
the minimum expense of energy that is necessary for life in a resting organism. |
| behavioral |
of or concerning the behavior of a person, animal, or other organism. |
| bioavailability |
the extent to which a substance in the soil can be taken up by a living organism. [1/2 definitions] |
| bisexual |
an organism having both male and female sexual organs; hermaphrodite. [1/5 definitions] |
| blocker |
a drug or other substance that inhibits or prevents a biochemical reaction in an organism. [1/2 definitions] |