Unit 5: Animal Biology
Approximately how many animal species have been described so far?
1 million
History of animal life on earth in order
1. appearance of invertebrate animals 2. the cambrian explosion of animal diversity 3. appearance of vertebrate animals 4. colonization of land 5. the post-Cretaceous explosion of mammalian diversity
An estimated ______ species of animals await discovery and classification. Multiple choice question.
2-5 million
The number of animal phyla now recognized is about
35
Which characteristics are included in the Lophotrochozoan grouping? Check all that apply.
A crown of tentacles. Trochophore larvae.
Which is a blastula?
A hollow sphere of cells produced early in the development of an animal embryo
Animal that lacks a fluid-filled body cavity
Acoelomate
Multicellular heterotrophs lacking cell walls are known as
Animals
Your instructor has asked you to provide evidence of the common ancestry of animals found in the animal body plan. Which of the following statements accurately provides this evidence? Check all that apply.
Animals from both the protostome and the deuterostome lineages can have a coelom, this is an example of a convergent evolution. Protostomes undergo spiral cleavage whereas deuterostomes undergo radial cleavage.
Your study partner likes to consider the facts before beginning to discuss the concepts when preparing for exams. She asks you to support the concept that "animals have a unique body plan" with factual statements concerning an animal's body plan that set the animals apart from other groups of living creatures. Which of the following would be appropriate to include in your response? Check all that apply.
Animals have unique attributes that often arise through their development. Animals can be acoelomates, pseudocoelomates, or coelomates which influences how they move about in their environment.
For a review session in preparation for an animal diversity exam, you asked each of the attendees to submit a statement concerning animals and the characteristics that define them as a group. Which of the statements below is most likely to classify a creature specifically as an animal and to exclude non-animals from inclusion in the group?
Animals require the use of Hox genes during development, have collagen genes, and have specific rRNA molecules that are similar among all animals.
What end of the animal body is towards the front or head?
Anterior
You are given a new animal species to study. You note that it possesses segmentation. Based entirely on the knowledge that it is segmented, to which of these phyla might the new species belong?
Arthropoda. Annelida. Platyhelminthes. Chordata.
Animals that are bilaterally symmetrical are placed in the group
Bilateral
Animals that have a dorsal and a ventral side, have an anterior and posterior end, and exhibit cephalization belong to the
Bilateria
Which of these animal groups exhibit radial symmetry?
Cnidarians
Animal with a fluid-filled body cavity lined with tissue from the mesoderm
Coelomate
Which of the following is the most likely ancestor from which animals evolved?
Colonial flagellated protist
What happens during gastrulation?
Different cell layers are produced in a developing embryo.
what is side of the body is the upper side?
Dorsal
Your study group has met to discuss animal phylogenetic trees in preparation for proposing a research project for the last few weeks of the semester. The group begins by reviewing what they know about animal phylogenies. Which of the following is the most accurate?
Early efforts to organize animals into groups were based on morphological features.
You are presented with a newly discovered invertebrate species. As you observe it in your lab, you note that the animals shed their skin. Which designation might this lead you to consider?
Ecdysozoa.
An organism in your lab has issues with a malformed central nervous system that can be traced all the way back to the embryonic stage. To further investigate this issue, which germ layer would you want to examine closely to get an idea of exactly how the malformation occurred?
Ectoderm.
All animals belong to the domain
Eukarya
Which of the following include features traditionally used by biologists to classify animal diversity?
Features of embryonic development Number of germ layers Type of body symmetry
As a scientific consultant on a movie about humans colonizing Mars, you have been asked to consider what fossil evidence would support the former existence of animal-like creatures on the planet. This prompts you to suggest which of the following pieces of evidence demonstrate a strong fossil record for animal-like creatures in the movie? Check all that apply.
Fossilized creatures with evidence of head and tail end as well as evidence of bilateral symmetry. Fossilized creatures with evidence of other creatures inside them that have been partially digested in a digestive tract. Fossilized genetic material that, when engineered into protist cell genomes, promotes the production of desmosomes, gap junctions, and tight junctions between protists.
Animals that would be placed in the group Bilateria include which of the following?
Horse Spider Lobster
Genes involved in pattern formation of the body and appendages in early embryos are :
Hox gene
Which of the following include functions of the fluid in the body cavity of an animal?
It provides shape and support. It can act as a circulatory system. It plays a role in animal movement.
What are germ layers?
Layers of cells in an embryo that form the organs
Molecular-based phylogenies place the phylum Platyhelminthes in the Protostomia. How do scientists best explain the morphological differences between flatworms and the other members of the Lophotrochozoa?
Modern Platyhelminthes do not have a coelom but did originate from an ancestor that had one.
Select the reasons why choanoflagellates are thought to be the closest living relatives to animals. Check all that apply.
Molecular comparisons between choanoflagellates and simple animals are similar. They are similar to the cells of simple animals.
Which of the following statements about using molecular data for phylogenetic trees are correct?
Molecular data provide a greater degree of accuracy than morphological data when building phylogenetic trees. When using molecular data to build animal phylogenetic trees, the evaluation of multiple, different genes is preferred.
The molecular basis of animal classification focuses on genetic sequence data. Check all of the characteristics that would apply to this approach.
Molecular techniques to evaluate relatedness primarily compare the sequences of DNA or RNA. New evidence from molecular techniques suggests that the Annelida and the Arthropoda are not as closely related as traditional approaches would indicate. The disadvantage of using molecular approaches for animal classification is that the information collected is more difficult to quantify than traditional approaches using body plans.
Check all the phyla that are considered to be lophotrochozoans.
Mollusca Platyhelminthes Annelida
What characteristics found in all animals?
Multicellularity/Characteristic cell junctions/Heterotrophic/Extracellular matrix
Which of these explanations is considered one of the most likely reasons for the rapid increase in animal diversity around the time of the Cambrian Explosion?
New predators evolved new abilities, meaning prey species rapidly needed to evolve defenses, to which the predators needed to evolve new ways of attacking, and so forth.
In what supergroup are animals classified?
Opisthokonta
You are asked to study a new species, and you are presented with a miniscule amount of DNA from that species. If you do not find a way to increase the volume of the DNA sample, you will not be able to work with the sample at all. which of these techniques amplifies DNA?
PCR.
Which of the following animal characteristics occurs only within the Bilateria?
Presence of a fluid-filled body cavity
What morphological features have traditionally been used to classify animals, but are now recognized as being less useful in determining evolutionary relationships than originally thought?
Presence/absence of a coelom Segmentation
Animal with a body cavity not completely lined with tissue from the mesoderm
Pseudocoelomate
An animal that can be divided into two identical halves by any longitudinal plane passing through the central axis exhibits
Radial symmetry
Which of the following statements about the number of embryonic germ layers is true?
Radially symmetric organisms have two germ layers, while bilaterally symmetric organisms have three.
Which of the following groups of animals are asymmetric? Multiple choice question.
Sponges
Butterflies and their caterpillars are insects.Caterpillars shed their outer layer when they grow bigger, then shed again as part of molting to become butterflies. Based upon this information caterpillars belong to which groups ?
The Protostomia The Ecdysozoa
Which of the following accurately describes animals with a segmented body plan?
The animal's body is divided into nearly identical units.
You are studying during the summer session at a field site in the western United States. During your studies, you stumbled upon a creature that is unfamiliar to you and does not allow for easy classification. As you grapple with whether or not this creature is an animal you must reconsider the characteristics of animals. Which of the following statements supports that your novel creature is an animal?
The creature is a multicellular heterotroph that reproduces sexually, appears to have a basic nervous system, and has collagen-producing genes.
What statement about the endoderm and ectoderm is correct?
The ectoderm differentiates into the nervous system and epidermis, while the endoderm lines the digestive tract.
Forelimbs form at the junction of the neck and thoracic vertebrae, the position of which is controlled by HoxC-6 genes. Several kinds of vertebrates from different classes are limbless, including limbless lizards, and amphibians known as caecilians. All descended from limbed forms. On the basis of recent research in genetics, what would you conclude about the functioning of their HoxC-6 genes?
The site of expression of their HoxC-6 genes may have moved anteriorly until the level of expression has eliminated the neck region.
If two otherwise dissimilar organisms share similar genomic DNA, to what would you attribute the genomic similarity?
The two taxa are more closely related than formerly believed.
How are presence of a coelom and segmentation used to classify animals?
They are useful in describing body structure, but less useful in understanding evolutionary relationships.
Which of the following is true of animals within the group Bilateria?
They have a left and right side that are mirror images of each other.
Which of the following statements best describes the difference between triploblastic and diploblastic animals?
Triploblastic animals develop a mesoderm; diploblastic animals do not.
T/F Radial symmetry is common in cnidarians and bilateral symmetry is common in protostomes and deuterostomes.
True
What are features traditionally used by biologists to classify animal diversity? Multiple select question.
Type of body symmetry Presence/absence of different tissue types Patterns of embryonic development
An animal is an organism best described as being:
a multicellular heterotroph that lacks cell walls and is motile at some point during its life cycle
Animals lacking a body cavity are called
acoelomates
Cephalization is an advantage in animals because it
allows for detection and response to predators and other encountered dangers allows animals to better detect and consume prey
The polymerase chain reaction (PCR) is used as a tool for
amplifying the amount of DNA to provide a large sample.
In the deuterostomes, the blastopore of the animal becomes the
anus
The fluid in the body cavity of an animal can:
assist with movement, act as a circulatory system, and provide shape
An animal that can be divided only by a vertical plane along the midline to create two identical halves exhibits:
bilateral symmetry
Which of the following is true of deuterostomes?
blastopore develops into anus
The Bilateria are divided into three major classifications based upon the structure of the
body cavity
The ability to detect and respond to food by animals that encounter their environment initially with their head is an advantage gained through:
cephalization
The closest living relatives of animals are the
choanoflagellates
The closest living relatives of animals are the ______.
choanoflagellates
Which of the following are features associated with animals that are radially symmetric?
circular- or tubular-shaped with a mouth at one end can be divided equally by any longitudinal plane passing through the central axis
Within the Bilateria, animals can be divided into three major divisions based on the presence and structure of a body cavity called the
coelom
Providing support and shape to the body of an organism and cushioning internal organs against injury from external forces are two of the advantages of having a
colem
The recent reassessment of animal classification is the result of
comparison of molecular data.
Advantages of a body cavity include
cushioning internal organs acting as a rudimentary circulatory system providing support and shape to an organism enabling movement and growth of internal organs independently of the outer body wall
In Blank______, the blastopore becomes the anus, and the mouth is formed from a secondary opening
deuterostomes
What are animals of the Radiata that have only two germ layers referred to :
diploblastic
The nervous system and the epidermis arise from the embryonic germ layer called the
ectoderm
while the layer of cells differentiating into the nervous system and epidermis is called the
ectoderm
Name the germ layers
ectoderm, mesoderm, endoderm
The layer of cells that lines the primitive digestive tract (the archenteron) during gastrulation is called the
endoderm
Ectoderm is essential in the formation of the:
epidermis and nervous system
t/f Redundancy of body parts is not an advantage that segmentation provides.
false
t/f Segments are just copies of each other, so when they expand or contract they do so at the same time and in the same way
false
Place the steps of germ layer formation in sequential order:
fertilization produces a zygote. cleavage. formation of blastula. gastrulation begins. formation of distinct endoderm, mesoderm, and ectoderm.
A coelom is important because it allows organs to be cushioned by _____ that is relatively incompressible.
fluid
What is a coelom?
fluid filled body cavity
In the developing embryo, invagination of the blastula, known as ______, is necessary to allow germ layers to form.
gastrulation
The formation of different cell layers in a growing embryo is called
gastrulation
Embryonic cell layers are called:
germ layers
An acoelomate is an animal that
has neither a coelom nor a pseudocoelom
The anterior end of an animal's body is the ______ region of the body.
head
A fluid-filled body cavity surrounded by muscle that provides shape and support to the animal's body is called
hydrostatic skeleton
The first animals did not have a backbone. These types of animals are collectively called
invertebrates
Protostomes are animals where the embryonic blastopore becomes the
mouth
If a coelom had been present in a species but was then lost over time, which function would you hypothesize could be most affected?
muscular.
what is the tail end?
posterior
Animals that undergo embryonic development where the embryonic blastopore develops to become the animal's mouth are
protostomes
Animals can be classified by the way their zygotes subsequently divide to form a multicellular individual; the embryological pathway can proceed by either:
radial or spiral cleavage.
Cnidarians (jellyfish and coral) are
radial symmetric animals.
Animals that are circular or tubular in shape are typically
radially symmetric
During the Cambrian Explosion, many types of animal bodies evolved with different shapes, a number of limbs, and many other variations. The evolution of Hox genes is thought to have been very important to generating all this diversity because _________ changes in the expression of Hox genes lead to _________ variation among body parts and shapes.
simple; large.
A major difference in embryo development between sponges and other animals is
sponge embryos do not develop germ layers
Some of the earliest-diverging animals, such as____________ , had no plane of symmetry.
sponges
The classification of animals as radial or bilateral is based on each group's body:
symmetry
When an animal has balanced proportions of the body on either side of a median plane, then the animal is said to have________ body .
symmetry
Animals possess specialized:
tissues
Animals of the Bilateria with all three distinct germ layers are referred to as:
triploblastic
T/F All animals have cell junctions
true
T/f Diploblasts have endo- and ectoderm that is separated by acellular mesoglea whereas triploblasts have endo- and ectoderm separated by cellular mesoderm.
true
T/f Gastrulation is brought about by an inward folding of the blastula.
true
t/f Large differences in body form can result from only small differences of gene expression
true
t/f Locomotion is more efficient in segmented animals because individual segments can move semi-independently.
true
t/f Segmented species can evolve different shapes without having to invent new genes
true
Morphological and developmental features typically used to classify animals into taxonomic groups include :
type of body symmetry, number of germ layers, and features of embryonic development
Morphological and developmental features typically used to classify animals into taxonomic groups include:
type of body symmetry, number of germ layers, and features of embryonic development
The underside or lower surface of the body is called the ______ side
ventral
Traditional and molecular phylogenies disagree on which one of the following issues?
whether the appearance and type of coelom is important in interpreting phylogeny.