ACTUAL QUESTIONS AND CORRECT
ANSWERS
altruism - CORRECT ANSWER behavior of an animal that benefits another at its own
expense.
air sacs - CORRECT ANSWER an extension of a bird's lung cavity into a bone or other
part of the body
Amnion - CORRECT ANSWER the innermost membrane that encloses the embryo of
a mammal, bird, or reptile
Amniota - CORRECT ANSWER are a clade of tetrapod vertebrates comprising the
reptiles, birds, and mammals. Amniotes lay their eggs on land or retain the fertilized egg
within the mother, and are distinguished from the anamniotes (fishes and amphibians), which
typically lay their eggs in water.
Amphibia - CORRECT ANSWER Amphibians are ectothermic, tetrapod vertebrates of
the class Amphibia.
archenteron - CORRECT ANSWER the rudimentary alimentary cavity of an embryo at
the gastrula stage.
Archosaur - CORRECT ANSWER a reptile of a large group that includes the dinosaurs
and pterosaurs, represented today only by the crocodilians.
Arthropoda - CORRECT ANSWER An arthropod is an invertebrate animal having an
exoskeleton, a segmented body, and paired jointed appendages. Arthropods form the phylum
Euarthropoda, which includes insects, arachnids, myriapods, and crustaceans.
, Aves - CORRECT ANSWER birds
Bilateria - CORRECT ANSWER The Bilateria or bilaterians, or triploblasts, are
animals with bilateral symmetry, i.e., they have a head and a tail as well as a back and a belly;
therefore they also have a left side and a right side.
bivalves - CORRECT ANSWER an aquatic mollusk that has a compressed body
enclosed within a hinged shell, such as oysters, clams, mussels, and scallops.
blastopore - CORRECT ANSWER the opening of the central cavity of an embryo in
the early stage of development.
blastula - CORRECT ANSWER an animal embryo at the early stage of development
when it is a hollow ball of cells.
cephalopod - CORRECT ANSWER an active predatory mollusk of the large class
Cephalopoda, such as an octopus or squid.
Choanoflagellate - CORRECT ANSWER The choanoflagellates are a group of free-
living unicellular and colonial flagellate eukaryotes considered to be the closest living
relatives of the animals.
choanocyte - CORRECT ANSWER a flagellated cell with a collar of protoplasm at the
base of the flagellum, numbers of which line the internal chambers of sponges.
coelacanths - CORRECT ANSWER The coelacanths constitute a now rare order of fish
that includes two extant species in the genus Latimeria
coelem - CORRECT ANSWER the body cavity in metazoans, located between the
intestinal canal and the body wall.
Convergent - CORRECT ANSWER relating to or denoting evolutionary convergence.