Download Biol 211 (2) Chapter 33 KEY

Unit #2 Study Guide
Biology 211 (2) Week 3
Beginning of Chapter 33!
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VOCABULARY (Define each term in your own words)
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Acoelomate: An
animal that
lacks an
internal body
cavity
Blastopore: An opening
(pore)in the surface of
some early embryos,
through which cells move
during gastrulation
Bilateral symmetry:
Cleavage: mitotic
one plane of symmetry cell division
without cell
growth and no
change in cell
size
Coelom: a fluidfilled space
separating the
digestive tract
from the outer
body wall with
the mesoderm
Central nervous system
(CNS): Large number of
neurons aggregated into
clusters called ganglia;
vertebrates consists of
the brain and spinal cord
Choanoflagellates:
protists that are close
living relatives to
animals
Deuterostome:
Pattern of
embryonic
development of
anus first
Diploblasts: Animals that
have two types of tissue
Ectoderm: gives rise to Endoderm: gives
skin and nervous
rise to the lining
system
of the digestive
tract
Coelomate: An
animal that has a
true coelom,
completely lined
with mesoderm
Gastrulation: a
Germ layers: three basic
rearrangement types of tissue formed
of the embryo; during gastrulation
folds into the
blastocoel,
formation of
layers (i.e. germ
layers)
Mesoderm: gives rise
to the circulatory
system, muscles, and
internal structures
such as bones and
organs
Neural net: A
nervous system in
which neurons
are diffuse
instead of being
clustered into
large ganglia or
tracts; found in
cnidarian and
ctenophores
Protostome:
Pattern of
embryonic
development,
mouth first
Radial symmetry:At
least two planes of
symmetry
Sessile: adults
live permanently
attached to a
substrate
Triploblasts:
Animals that
have three
types of tissues
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Pseudocoelomate: An
animal that has a coelom
that is only partially lined
with mesoderm
Unit #2 Study Guide
KEY CONCEPTS (Answer each question completely and in your own words)
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1. Approximately how many different animal species are alive on Earth currently. How
many those species have been described and given scientific names?
a. May be as high as 100-200 million animal species on Earth currently
b. Only about 1.3 million have been described/named
2. List at least three characteristics of animals. What is a key difference between
animals and fungi?
a. All animals are multicellular
i. Lack cell walls but have an Extracellular matrix (ECM) which is made of
collagen and holds structures together
b. All animals are heterotrophs
i. They obtain carbon from other organisms
ii. Most ingest, rather than absorb unlike fungus
c. Obtain nutrition through ingestion
d. Animals ingest their food, while fungi absorb it
3. What evidence is there that multicellularity originated in a sponge-like animal? What
protist is the closest relative to animals?
a. The closest relative is choanoflagellates
b. Sponges are the earliest animals to appear in fossil record more than 600
million years ago
c. Sponges are sessile and feed in a similar way to choanoflagellates (the beating
of flagella creates water currents that bring organic debris toward the feeding
cells)
d. Choanoflagellates form colonies and some biologists once considered sponges
to be colonies of single-celled protists
4. Compare and contrast choanoflagellates and sponges. What structure(s) are found in
sponges, but not choanoflagellates? How do these organisms feed? How do they move?
a. Spicules and epithelium layer are found in sponges, but not choanoflagellates.
b. Both feed using flagella currents with cells (Sponges feeding cell=choanocyte)
c. Both are sessile
Unit #2 Study Guide
5. What are the 3 embryonic tissue layers called? What adult tissues are formed from
each of these 3 layers?
a. In diploblasts there are the ectoderm and endoderm layers
b. In tripoblasts there are there layers: ectoderm, mesoderm, and endoderm
i. Derm=skin, ecto=outer, endo=inner, meso=middle
ii. Ectoderm gives rise to skin and nervous system
iii. Endoderm gives rise to the lining of the digestive tract
iv. Mesoderm gives rise to the circulatory system, muscle, and internal
structures such as bone and most organs.
6. Compare and contrast bilateral and radial symmetry. Give examples of animals of each
type of symmetry. Which type of symmetry is most common in sessile animals?
a. Radial symmetry is identical all of the way around, while bilateral symmetry
has left and right sides/front and back.
b. Radial symmetry is found in diploblastic animals, such as jellyfish, found in
sessile animals.
c. Bilateral symmetry is found in triploblastic animals and leads to cephalization
(the formation of the head)
7. Compare the nervous system found in sponges, cnidarians and earthworms. Can you
train a jellyfish? Why or why not?
a. Sponges generally lack both nerve cells and symmetry
b. Cnidarians have a nerve net, which is able to sense something instantly, but it
is a stimulus response. Cannot learn with nerve net, so they cannot be trained.
c. Earthworms have a central nervous system (CNS) and are able to learn
8. What is a coelom? Draw a cross section of an acoelomate, pseudocoelomate, and
coelomate animal.
a. The coelom is a fluid filled cavity between the inner and outer tube that is
completely surrounded by the mesoderm.
Unit #2 Study Guide
9. Compare and contrast protostome and deuterostome development from zygote to
gastrulation. Does the blastopore become the mouth or the anus in a protostome
animal?
a. Protostomes: the mouth develops before the anus and blocks of mesoderm
hollow out to form the coelom
b. Deuterostomes: The anus develops before the mouth and pockets of mesoderm
pinch off to form the coelom
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10. From the beginning of the zygote formation, list and explain the actions that occur to
eventually form the gastrula.
a. Zygote (fertilized egg) —> Cleavage (mitotic cell division w/o cell growth)—>
Blastula (has blastocoel)—> Gastrulation (rearrangement of embryo, folds into
the blastocoel and forms germs layers)—> Gastrula (has blastopore)
Unit #2 Study Guide
11. What are the two major protostome clades?
a. Lophotrochozoa and Ecdysozoa
12. In protostome animals, the blastopore becomes the _______ of the digestive system,
and the cleavage is _______ and _________.
a. mouth; spiral; determinate
13. In deuterostome animals, the blastopore becomes the _______ of the digest system,
and the cleavage is ______ and ________.
a. anus; radial; indeterminate
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14. Describe the difference between cleavage that is determinate and cleavage that is
indeterminate.
a. Determinate cleavage involves the removal of cells, and cells that are already
specified on what type of cell they are going to be.
b. Indeterminate cells are similar to a blank slate and are not yet specified on
what type of cell they are going to be.