Exam 2 BIO 122 Flashcards
What are animals?
Multicellular heterotrophic organisms that ingest other organisms
Morphological diversity is used to classify/determine phylogeny of animals based on:
Symmetry
Primary tissues
Mode of development
Body cavity type
What type of symmetry do most animals have?
Bilateral symmetry.
What type of animals have radial symmetry?
Cnidaria and Echinoderms (Jellyfish and Starfish)
How many tissue layers do all animals have (except sponges) have during embryonic development?
two or three tissue layers.
Animals that have 2 tissue layers are called…
Animals that have 3 tissue layers are called…
Diploblastic
Triploblastic
What is the outer, inner, and middle layers called?
Ectoderm - outer layer
Endoderm - inner layer
Mesoderm - middle layer
These are the primary tissues present early in embryonic development, they form the animals tissues (skin, muscle, etc).
Most animals undergo development involving a ____ and a ____ stage.
blastula, gastrula
Most animal bodies are ____ and make ____ sex cells.
diploid, haploid
After an egg is fertilized…
Cells divide (cleavage) without the zygote getting larger. Then go through blastula and gastrula.
What is blastula and gastrula?
A blastula is an early embryonic stage characterized by a hollow ball of cells formed through cleavage during embryogenesis. This fluid-filled structure is crucial for the development of more complex organisms.
A gastrula is a later stage in embryonic development where the blastula undergoes a process called gastrulation, resulting in the formation of germ layers (ectoderm, mesoderm, and endoderm) and the establishment of the basic body plan of an organism.
What are the two major modes of animal body development?
Protostome - Spiral and determinate cleavage. Solid masses of mesoderm split and form coelom (formation). Mouth develops from blastopore.
Deuterostome - Radial and indeterminate cleavage. Folds of archenteron form coelom (formation). Anus develops from blastospore.
Early cell divisions can be aligned (x) or offset (y)
x = radial cleavage
y = spiral cleavage
Cells can be ____ or ____.
determinate (fated) or indeterminate (plueripotent)
Where the blastula invaginates forms either the ____ or ____ first. This begins ____.
mouth, anus, gastrulation
Animal body cavities
Acoelomates - Have no spaces between tissue layers.
Pseudocoelomates - Have a space between the endoderm and mesoderm.
Coelomates - Have a space within the mesoderm. Vertebrates are coelomates.
Which character state do you think would be the hardest to evolve repeatedly (least likely to be convergent evolution)?
a. mode of symmetry
b. body cavity/coelem type
c. radial vs spiral cleavage
d. protostome vs deuterostome gastrulation
idk yet
What are the five supergroups of animals?
Porifera, Radiata, Lophotrochozoa, Ecdysozoa, Deuterostomia.
Animals are the sister group to ____ ____.
Choanoflagellate protists - are colonial, and feed using a flagellated cell (sponges do this too).
What’s the most basal animal?
sponges
When did animals likely originate?
710-780 mya. Sponges appear in the fossil record 710 mya.
Animals underwent an explosion of diversity…
Cambrian explosion 525-535 mya. Over half of the extant animal phyla appeared within a 10 million year time span in the fossil record.
Why was there an explosion of diversity in the Cambrian?
Hypotheses:
- Preservation bias: There only appears to be a rapid diversification because earlier fossils didn’t get preserved.
- Oxygen increase lead to ecological diversity.
- Invention of predators lead to predator-prey “arms race”.
- New classes of genes allowed for rapid morphological change.
Study the pictures in discord
you fucking retard