Test 1 Biology Flashcards
Radial Symmetry
At least two planes of symmetry. Symmetry in which the body can be divided into mirror-imaged halves by any plane through its central axis [like Cnidarians].
Bilateral Symmetry
Body symmetry in which a cenral longitudinal plane divides the body into two equal but opposite haves [like humans]. Only one plane of symmetry.
Biradial Symmetry
Both radial and bilateral [just ctenophorans have this type of symmetry, they are alos called comb jellies].
Asymmetry
no symmetry; organisms with no planes of symmetry.
Diploblastic
Organisms with tow germ layers: endoderm and ectoderm.
Triploblastic
Organisms with three germ layesL endoderm, ectoderm, and mesoderm.
Endoderm
inner layer, usually derives the digestive tract.
ectoderm
outer layer, skin/nervous system.
Mesoderm
middle layer, organs, muscle skeleton.
Coelomates/Eucoelomates
Organisms with true coelom [or body cavity] derived ONLY from Mesoderm germ layer.
Acoelomates
Orgnisms with no coelom or body cavity
Pseudocoelomates
Organisms with a false or face coelom [or body cavity] derived from Endoderm ad Mesoderm.
Dioecious
Having separate sexes.
Hermaphroditic
Having both male and female reproductive organs.
Complete digestive system
Two openings [one works as the mouth and the other one as the anus]. It is also called alimentary canal.
Incomplete digestive system
One opening [works as both mouth and anus[.
Open circulatory system
System in which the fluid [in this case called hemolymph, not blood] bathes the tissues and organs directly and there is no distinction between circulating fluid and interstitial fluid].
Closed Circulatory system
system in which fluid [in this case blood] is confined to vessels and is kept separate from the interstitial fluid.
Cephalization
An evolutionary trend toward the concentration of sensory equipment at the anterior end of the body. [“Formation of head”]
Parasitism
symbiotic relationship in which one organism, the parasite, benefits at the expense of another, the host, by living either within or on the host.
Adaptive Radiation
Period of evolutionary change in which groups of organisms form many new species whose adaptations allow them to fill different ecological roles in their communities [like mollusks]
Lophotrochozoans
organisms that produce a trochophore larvae and have lophphore.
Ecdysozoans
Organsms that molt
What findings does the fact that protostomes are divided into 2 subgroups suggest?
That protostomes are monophyletic group