Biology Exam One

• Most of the basic body plans of animals have evolved long after the Cambrian explosion; in fact, many new phyla continued to evolve several millennia after the Cambrian explosion. However no further diversification of animals within-phylum occurred after the Cambrian explosion. This statement is false.
• Water to land transition of protostomes happened multiple times independently as they diversified across different lineages.
• Cephalization


  Evolution of cephalization with formation of central nervous system. It is evident mostly if not exclusively in bilaterally symmetrical animals - Concentrations of sensory organs, sensory cells, brain or cerebral ganglia in the leading end of the animal body
• The closet relatives of animals is Choanoflagellates
• Sponges


  • Adults are sessile while larvae are mobile
• Phylum Cnidaria – they have choanocytes – they are triploblastic – all adult stages are planktonic organisms – all of the above are incorrect statements
• Sponges – they are filter feeders that largely feed on plankton
• Radial symmetry


  In radially symmetrical animals, the body can be divided into mirror images along a single plane.
• Sponges are considered the most basal clade in the animal kingdom
• Muscular system originates from endoderm
• Epidermis and digestive track originate from both endoderm and ectoderm can develop in those structures
• Productive reproductive organs cannot be considered a function in the coelom
• External fertilization is an asexual reproduction mode observed in Cnidaria
• Coelom


  A fluid filled cavity lined by mesoderm
• Characteristics of animals


  • Obtain energy, carbon, and other nutrients from other organisms
  • Possess excitable cells
• All Cnidarians are sedentary with no mobile life cycle stages is an incorrect statement
• Cnidarians possesses a gastrovascular cavity, two germinal layers, and reproductive tissues
• Sponges do not have a simple respiratory organ system
• Sponges (Porifera)


  • Presence of choanocytes in the body cavity
  • Have spicules made of either silica or calcium carbonates
• Phylum Platyhelminthes (flatworms) have a digestive system that tracts only have one opening for ingestion and elimination of wastes
• All members of Phylum Bryozoa (moss animals) have not completely lost the lophophore
• Rotifers do have cilia and are not exclusively sessile
• Annelids


  • Belong to the group Lophotrochozoans
  • Have coeloms and show segmentation
  • Use hydrostatic function of their coelom for locomotion
• Feeding styles found among Annelids


  • Filter feeding
  • Ectoparasites
  • Predation
• Mollusca


  • Have hemocoel
  • No segmentation
  • Occur in marine, terrestrial and freshwater habitats
• Coelom


  The coelom contributed to the formation of a hydrostatic skeleton, allowing greater range of motion
• Rotifera (Rotifersa) does contain endoparasites or ectoparasites
• Ecdysozoans


  • Grow intermittently by molting
  • Arthropods and roundworms are Ecdysozoans
  • Hormones regulate molting in ecdysozoans
• Insects


  • Sexual reproduction may involve courtships and sexual displays
  • Some insects have social organizations and caste systems in their colonies
  • They have compound eyes and a pair of antennae
• All deuterostomes have in common is the blastopore becomes the anus
• Chiton


  The exoskeleton is divided into multiple (eight) dorsal plates
• Sea slugs can be toxic
• Planarians lack respiratory and circulatory systems. This deficiency does not cause a problem because none of their cells is far from the gastrovascular cavity or from the external environment.
• Centipede vs Millipede


  Presence vs absence of poisonous claws will help to determine
• Arthropods


  • Have reduced coeloms and a hemocoel
  • Have joined, segmented appendages
  • Show segmentation as well as tagma formation in certain organisms
• Larval and adult morphologies are not completely different among hemimetabolous insects while larvae morphologically resemble miniature adults with holometabolous development
• Both larvae and adults occupy the same or similar habitats in hemimetabolous life cycles while larvae and adults occupy different habitats among insects that undergo holometabolous development
• Larval vs adult food selection does not differ between hemimetabolous and holometabolous life cycles
• The pupal stages are only observed in holometabolous life cycles, not in hemimetabolous life cycles
• Gastropod vs Bivalve


  Gastropods have a very large foot used for locomotion while bivalves use their foot for anchoring to the substrate