SQ #1

what specific type of flagellated protist is believed to be the closest living relative to animals?
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what specific type of flagellated protist is believed to be the closest living relative to animals?
Choanoflagellates
by what specific feeding method do both these opisthokont group and ukonta group, these extant flagellated protists and the hypothesized common ancestor of animals obtain food?
filter feeding.
the three lines of evidence that these extant flagellated protists are closely related to animals.
1. similar collar cells have been identified in other animals.
2. morphologically, choanoflagellates and poriferas collar cells are nearly identical.
3. DNA sequences indicate that choanoflagellates and animals are sister groups. (they share their most recent ancestor.) also genes for cell signaling.
what are cadherin proteins in animals used for?
they play key roles in how animal cells attach to each other.
Explain how animal cadherin proteins are believed to have originated from cadherin-like proteins in the protist ancestor of animals.
Animal cadherin proteins are believed to have originated by the rearrangement of protein domains found in choanoflagellates, plus the incorporation of a novel domain (the CCD domain).
Why was the evolution of these novel cadherin proteins a key event in the evolution of animals?
This new variation on the ancestral protein likely allowed the common ancestor of animals to use the protein in novel ways that caused cells to attach to each other and contributed to the origin of multicellularity in animals.
what animals have asymmetrical bodies?
sponges:
describe radial symmetry:
body symmetry arranged around a single central axis so that the organism can be divided into similar halves by any plane through the central axis.
what animals have radial symmetry:
cnidarians such as sea anenomes or jellies.
nervous system of radially symmetrical animals:
a nerve net is a diffuse network of neurons that conducts nerve impulses in all directions from a point of stimulus. it is found in radially symmetrical animals.
why do raidal symmetrical animals have nerve nets?a nerve net allows radially symmetrical animals to detect and respond to a stimulus regardless of what direction it came from.What is bilateral symmetry?animals that can be divided into two symmetrical halves on either side of a unique plane. ; which results in a right and left side. , anterior, posterior end of the body. and dorsal and ventral surfaces of the body.what type of animals have bilateral symmetry?mammals , arthropods.what is cephalization:it is the concentration of sensory organs and nervous tissue at the anterior end of the body, resulting in a head and brain.why has cephalization evolved as an accompaniment to bilateral symmetry?Bilaterally symmetrical animals typically move through their environment with their anterior end leading, so their anterior end is the first part of the body to encounter food, shelter, danger, etc. It therefore is adaptive to have a concentration of sensory organs and nervous tissue (to process the sensory information gathered) at the location on the body that is first encountering these stimuli. If the animal were to meet its world head first but have their sensory organs distributed evenly around the body, as in radially symmetrical animals, they would be less well equipped to sense stimuli. Similarly, if the animal were to meet the world head first but have its brain in the center, rear, or one side of the body, or have no brain at all, it would take longer for the nervous system to process the information.monoeciousHaving both male and female reproductive organs in the same individual (either simultaneously, as in an earthworm, or sequentially, as in a sheepshead fish that begins life as a female but may turn into a male.Give an example of a monoecious animal.as in a sheepshead fish that begins life as a female but may turn into a male.What is a coelom?A body cavity lined on both sides by mesoderm.explain what it means to be an acoelomate animal.The animal lacks a body cavity.Explain what it means to be a pseudocoelomate animal.The animal has a body cavity but it is lined on only one side by mesoderm (a "false coelom").Explain what it means to be a coelomate animalThe animal has a true coelom, as defined above.Gastrovascular cavityincomplete gut. that has only one opening, a mouth.complete gut:a complete gut is a digestive tract through which food flows in a one way direction, from the mouth to the anus.One benefit of having a complete gut is that each region of the gut evolves to be specialized for a certain task. What do you suppose is the advantage of having specialized regions?Specialization allows for higher efficiency, since each region evolves to be we particularly well- suited for its particular activity.germ layer:the embryonic tissue layers that will give rise to the various specific tissues and organs of an animal's body.Diploblastic animals: How many tissue layers do diploblastic animals have?twoDiploblastic animals: Name the specific germ layers of a diploblastic animalendoderm and ectoderm.Triploblasticanimals: How many tissue layers do triploblastic animals have?threeName the specific germ layers of a triploblastic animalEndoderm, mesoderm, and ectodermEndoderm germ layer develops into what?epithelial lining of digestive tract and respiratory tract, liver, pancreasMesoderm germ layer develops into what?heart, circulatory system, muscles, bonesEctoderm germ layer develops into what?skin, nervous system, eyes