BIO L1

• What % of animals are vertebrates?

  5%
• what % of species are already extinct?

  99%
• definition of an animal?

  Multicellular, heterotrophic eukaryotes with tissue that develops from embryonic layers.
• Animals must take in preformed organic molecules through ingestion, eating other organisms or organic material that is decomposing.
• The multicellular bodies of animals are held together with the extracellular proteins, especially collagen.
• Animals have two unique types of tissues:

  nervous tissue for impulse conduction & muscle tissue for movement
• Animals lack...

  cell walls
• Most animals reproduce sexually, with the diploid stage usually dominating the life cycle.
• In most species, a small flagellated sperm fertilizes a larger, nonmotile eggs.
• The zygote undergoes cleavage, a succession mitotic cell divisions, leading to the formation of a multicellular, hollow ball of cells called the blastula.
• The animal's last common ancestor was most likely a colonial flagellated protist that lived over 770 million years ago in the Precambrian era.
• The single celled flagellated protist was probably related to choanoflagellates, a group that arose about a billion years ago.
• How do animals store their carbohydrates?

  glycogen
• The first branch split on the phylogenetic tree is into Eumetazoa and Parazoa, what is the difference


  presence of true tissue (Eumetazoa only)
• The parazoans, phylum Porifera or sponges, represent an early branch of the animal kingdom. Sponges have unique development and structural simplicity.
• The Eumetazoans are divided into two major branches, partly based on body symmetry. What are the two branches?

  Radial symmetry and the other major branch, the Bilateria
• What animals/phyla posses radial symmetry?

  Members of the phylum Cnidaria (hydras, jellies, sea anemones and their relatives) and phylum Ctenophora (comb jellies) have radial symmetry and are known collectively as the Radiata.
• Bilateria has bilateral symmetry with a .....

  dorsal and ventral side, an anterior and posterior end, and a left and right side.
• What is cephalisation?


  an evolutionary trend toward the concentration of sensory equipment on the anterior end. (come alongside bilateral symmetry) Moves along the central nervous system that moves from the head end to the tail end as a longitudinal nerve cord.
• What are germ layers?

  concentric layers of embryonic tissue that form various tissues and organs, differs between radiata and bilateria.
• diploblastic (radiata)


  2 germ layers , ectoderm and endoderm
• triploblastic (bilatera)


  the third germ layer is the mesoderm which lies in between the other two layers - develops into muscle and most other organs between the digestive tube and the outer covering.
• Acoelomates (the phylum Platyhelminthes) have....

  a solid body and lack a body cavity
• what is the term for an organism that has a body cavity, but it is not completely lined by mesoderm?

  pseudocolour ( lies in between the mesoderm and the endoderm.)
• Coelomates are organisms with a .......

  true coelom, a fluid-filled body cavity completely lined by mesoderm.
• the coelomate phyla can be divided into two grades based on their differences in development

  protostomes & deuterostomes.
• X3 examples of protosomes


  The molluscs, annelids, arthropods
• name X2 phyla that belong to deuterotsomes

  Echinoderms &chordates
• the differences between protosomes and deuterostomes are, centre on cleavage pattern, coelom formation, and blastopore fate.
• protosomes undergo...


  spiral and determinate cleavage
• deuterostomes undergo...


  radial and intermediate cleavage
• what happens during coelom formation in protosomes?

  solid masses of mesoderm split to form the coelomic cavities, called schizocoelous development.
• what happens during coelom formation in deuterostomes?

  mesoderm buds off from the wall of the archenteron and hollows to become the coelomic cavities, called enterocoelous development.
• Protosomes fate of the blastopore?

  blastopore develops into the mouth and a second opening at the opposite end of the gastrula develops into the anus.
• deuterostomes fate of the blastopore?

  the blastopore usually develops into the anus and the mouth is derived from the secondary opening.