Bio exam 3 Flashcards
animals
What are some general features of animals?
Multicellularity, no cell walls, heterotrophy, active movement, diversity of form and body plans.
What habitats do most animal phyla occur in?
Most phyla occur in the sea, though some live in freshwater and on land.
What is the only entirely terrestrial animal phylum?
Onychophora (velvet worms).
What is a key difference between animal reproduction and plant/fungi reproduction?
Animals do not have a multicellular, haploid gametophyte generation.
What is a blastula?
A ball of cells formed after the zygote undergoes mitotic divisions.
What are the five key innovations in animal evolution?
Symmetry, tissues, body cavity, embryonic development, segmentation.
What is radial symmetry?
Body parts arranged around a central axis, divisible into equal halves by any plane through the center.
What is bilateral symmetry?
Right and left halves are mirror images, with only one plane dividing them equally.
What is cephalization?
The concentration of nervous tissue and sensory organs at the anterior end of the body.
What does it mean that zygotes are totipotent?
They can give rise to all other body cells.
Which animals can disaggregate and reaggregate their cells?
Sponges.
What are the three germ layers in triploblastic animals?
Ectoderm, mesoderm, endoderm.
What are the three body cavity types?
Acoelomate (no cavity), pseudocoelomate (cavity between mesoderm and endoderm), coelomate (cavity within mesoderm).
What is the difference between open and closed circulatory systems?
Open: hemolymph bathes organs directly. Closed: blood circulates in vessels.
What is a blastopore?
The first opening in the embryo; becomes either the mouth or anus.
What is the difference between protostomes and deuterostomes?
Protostomes: mouth develops first. Deuterostomes: anus develops first.
What are the advantages of segmentation?
Redundant organs and independent movement of body segments.
What are Parazoa?
Animals that lack true tissues, like sponges.
What are Eumetazoa?
Animals with true tissues, including all animals except sponges.
What are characteristics of sponges (Phylum Porifera)?
No symmetry, sessile adults, filter feeders, ability to regenerate, no true tissues or organs.
What are choanocytes?
Flagellated collar cells that circulate water and capture food in sponges.
What are the two forms of cnidarians?
Polyp (sessile) and medusa (free-swimming).
What is the gastrovascular cavity?
Central digestive compartment with a single opening in cnidarians.
What is the function of nematocysts?
Stinging structures for prey capture and defense in cnidarians.
What are the two clades of Bilateria?
Protostomes and Deuterostomes.
What is the defining feature of Acoel flatworms?
Bilateral symmetry and lack of a coelom.
