Bio 11 Flashcards
(135 cards)
What are three different animal characteristics?
- Eukaryotic
- Heterotrophic by ingestion
- Multicellular with a high degree of cell specialization
What is radial symmetry
You can divide it a lot of times through its centeral axis and it will be the same
Organisms with radial symetery have a ___ shaped body with no ___
- Cylindrical
- Head, front or back
What is bilateral symmetry
You can only cut it into two equal halves, through the mid dorsal line (spine)
What does bilateral symmetry allow for?
Cephalization (Organs and everything being concentrated in torso resulting in an enlarged head)
What are germ layers
Primary layers created during embryo development that from the various tissues and organs
What are the three germ layers
Endoderm, mesoderm, and ectoderm
What does it mean when an animal has no germ layers
It means they are the most primitive with no organs or tissues
What does it mean when an organism is diploblastic
It means it has two germ layers, ectoderm and endoderm
What does the ectoderm make?
(Outer layer) Skin and nervous system
What does the endoderm make
(Inner layer) The endoderm makes the lining of the digestive track
What does it mean when an organism is triploblastic?
It means that it has all three germ layers
What does a mesoderm create?
The mesoderm creates most of the remaining internal organs and muscles
What is a body plan
The type of body cavity that an organism has
The evolution of a body cavity that provides a place for organs and organ systems to grow is called what?
Coelom
Acoelomates
No coelom and poorly developed organs
Pseudocoelomates
Pseudocoelomates have a body cavity between the endoderm and mesoderm layers, however there is no muscle around the gut and no co-ordination of food through their digestive tract. Only some organs develop through this space.
Example of a pseudocoelomate
Tardigrade, roundworms
Coelomates
Coelomates have a body cavity between the mesoderm of the body wall and around the gut, they have co-ordinated digestion and development of major organs
Example of a coelomate
Earthworm
What does segmentaion lead to
Specialized body regions
Non segmented organisms have ___ segments
No specialized
Example of non-segmented organisms
Flatworm
Segmented organisms have what?
Identical repeating sections