Chapter 32,33 : Animalia (1) Flashcards
What are the characteristics of animals?
- Multicellular, eukaryotic organisms
- Heterotrophic – ingest other organisms
for food and energy – many feeding
forms - Carbohydrate reserves stored as
glycogen - No cell walls
- Highly differentiated body cells
Differentiate between continuous and discontinuous life cycles.
Life cycles:
Some develop into a mature adult where adult looks like young –continuous (e.g.humans)
Discontinuous (e.g. grasshoppers) development ,Some go through morphologically distinct states – egg into larvae pupa metamorphosis adult
What are the steps of early development?
Stages of the early development:
- Zygote mitotic divisions (cleavage) —————–>blastula (hollow ball of cells)
——–>Gastrula germ layer formation – all adult body tissues can be traced back to one of these
What is archenteron?
Archenteron – a pouch formed by
gastrulation
- Archenteron opens to the outside
via the blastopore
Differentiate between radial and bilateral symmetry.
Radial Symmetry (symmetry found in flower pots)
* Often sessile in adults (jelly fish = major
exception)
* Diploblastic - 2 germ layers in embryo (endoderm
and ectoderm)
Bilateral Symmetry (e.g. arthropods and mammals)
* Has two axes of orientation
* Allows the development of anterior-posterior axis
* Dorsal (top) side and ventral (bottom) side
* Right and left side
What is cephalization?
Cephalization – aggregation of sensory
equipment (brain) at the anterior end of the animal, including the Central Nervous System.
What are the germ layers formed in the early embryo?
Germ layers of the early embryo form:
* ectoderm
* mesoderm
* endoderm
Explain ectoderm
- Ectoderm
- Covers the surface of the embryo
- Gives rise to the out covering of the animal
- Forms the central nervous system in some phyla
Explain endoderm
Endoderm
- Innermost layer
- Lines the pouch that forms during gastrulation
- Gives rise to the lining of the digestive tract and organs
such as lungs and liver in vertebrates
All bilaterally symmetrical animals have a third germ layer(Triploblastic), true or false?
True
Explain mesoderm
Mesoderm
* Forms between endoderm and ectoderm
* Forms the muscles and most other organs between the
digestive tract and outer covering of the animal e.g.
blood, bones etc
What is a coelom? What is a true coelom?
Fluid filled or air-filled space located between the digestive tract and
the outer body wall.
- True Coelom – forms from tissue derived from mesoderm.
Differentiate between acolemates and psuedocolemates?
Pseudocoelomates
* Body cavity formed from mesoderm and endoderm
* E.g. roundworm
Acoelomates
* Lack body cavity between the
digestive tract and outer body wall
* The area is filled with cells
* E.g. tapeworm, flatworms
What are the functions of a coelom?
- The fluid cushions the organs prevent injuries
- Internal organs can grow and move independently from body wall –allows for larger internal organs
- Serves as hydrostatic skeleton in soft bodied coelomates (e.g.,earthworm)
- Allows space for expansion of uterus during placental development of embryo, and serves as a site for maturation of eggs and sperm in many species
- Diffusion medium, or primitive circulatory system, for waste elimination, water balance
Differentiate between protostome and deuterostome development.
Protostome development – coelom forms from splits in the mesoderm
Deuterostome development – coelom forms from mesodermal out pocketing of the archenteron
Protostomes:The blastopore forms the mouth
Deuterostomes: The blastopore forms the anus
