Ch. 2 Flashcards
(122 cards)
1
Q
What is the primary focus of classification according to Charles Darwin?
A
Grouping beings according to their actual relationship and descent from common stocks.
2
Q
How long ago did multicellular life evolve from unicellular forms?
A
Over 3 billion years ago.
3
Q
Approximately how many animal species have been described and named?
A
About 1.7 million.
4
Q
What is the estimated number of animal species that await discovery?
A
At least another 10 million.
5
Q
What does the term ‘metazoans’ refer to?
A
Multicellular animals that generally develop from a blastula.
6
Q
What are the oldest known fossils of multicellular animals called?
A
Metazoans.
7
Q
What significant event in evolutionary history occurred around 542 million years ago?
A
The Cambrian explosion.
8
Q
What type of fossils are best studied from the Cambrian period?
A
Invertebrate fossils from the Burgess Shale.
9
Q
What is suggested by recent molecular studies regarding the divergence of animal body plans?
A
Most basic animal body plans existed at least 100 million years before being preserved as fossils.
10
Q
What does the term ‘diploblastic’ indicate in animal classification?
A
Animals that have only two distinct germ layers.
11
Q
What are the two germ layers in diploblastic animals called?
A
Ectoderm and endoderm.
12
Q
What additional germ layer do most metazoans possess?
A
Mesoderm.
13
Q
What is the significance of cephalization in bilateral animals?
A
It indicates the concentration of nervous and sensory tissues at one end of the animal.
14
Q
Fill in the blank: Animals that show bilateral symmetry can be divided into two mirror-image halves by a cut along the _______.
A
Anterior-posterior axis.
15
Q
What are the two main groups of animals based on the number of germ layers formed during embryogenesis?
A
Diploblastic and triploblastic.
16
Q
What is the term for animals with a true body cavity?
A
Coelomates.
17
Q
What are the two types of coelom formation in animals?
A
Schizocoely and enterocoely.
18
Q
True or False: All classification schemes for animals are entirely natural and reflect the true relationships among organisms.
A
False.
19
Q
According to the text, what must be determined before classifying animal species?
A
The degrees of similarity and difference that define each category.
20
Q
What major animal groups are represented among Cambrian fossils?
A
Nearly all of today’s major animal phyla.
21
Q
What is one reason why the fossil record may not accurately reflect the history of animal evolution?
A
It may be incomplete.
22
Q
Fill in the blank: The outermost layer of cells in diploblastic animals is called _______.
A
Ectoderm.
23
Q
What is a characteristic feature of bilateral symmetry?
A
Possessing right and left sides that are approximate mirror images of each other.
24
Q
What is the role of germ layers in embryonic development?
A
They give rise to distinctly different tissue and/or organ systems in adults.
25
What is the relationship between body symmetry and the evolutionary classification of animals?
Animals are categorized based on their body symmetry, either radial or bilateral.
26
What is the term used for the internal fluid-filled body cavity in coelomates?
Coelom
## Footnote
The coelom is lined with tissue derived from embryonic mesoderm.
27
What are the three basic plans of body construction in triploblastic animals?
Coelomate, pseudocoelomate, acoelomate
## Footnote
These classifications are based on the presence and formation of body cavities.
28
In which type of animals does the mouth form from the blastopore during embryonic development?
Protostomes
## Footnote
The term 'protostome' means 'first mouth.'
29
What is the embryonic origin of the mouth in deuterostomes?
Never from the blastopore
## Footnote
In deuterostomes, the mouth forms as a second opening.
30
What type of coelom formation is associated with protostomes?
Schizocoely
## Footnote
Schizocoely involves the formation of coelom by a split in mesodermal tissue.
31
How do coelomic cavities typically differ between protostomes and deuterostomes?
Protostomes: variable in number; Deuterostomes: generally tripartite
## Footnote
This refers to the number of coelomic cavities formed during development.
32
What cleavage pattern is typically seen in deuterostomes?
Radial, indeterminate
## Footnote
Indeterminate cleavage allows for the potential of cells to develop into a complete organism.
33
What cleavage pattern is associated with protostomes?
Spiral, determinate
## Footnote
In determinate cleavage, the fate of cells is fixed early in development.
34
Fill in the blank: Pseudocoelomates have an internal body cavity derived from the _______.
Blastocoel
## Footnote
This cavity is not formed by mesodermal derivatives.
35
What is the main characteristic of acoelomates?
No internal body cavity
## Footnote
The space between the body wall and gut is filled with solid mesoderm.
36
True or False: All protostomes exhibit spiral, determinate cleavage.
False
## Footnote
Some protostome species may exhibit characteristics typically associated with deuterostomes.
37
What is the significance of the term 'pseudocoelomate'?
It indicates a body cavity not formed by mesodermal tissue
## Footnote
The prefix 'pseudo' highlights that this cavity is not a true coelom.
38
What classification scheme is most familiar in biological taxonomy?
Linnaean system
## Footnote
This system includes ranks such as kingdom, phylum, class, order, family, genus, and species.
39
What is the biological significance of the category 'species'?
Members are reproductively isolated from other species
## Footnote
This isolation forms a distinct gene pool.
40
Fill in the blank: The scientific name of a species is composed of its _______ and _______.
Genus, species
## Footnote
This binomial nomenclature system helps in identifying organisms.
41
What is the biological significance of the category of species?
Members of one species are reproductively isolated from members of other species
## Footnote
This isolation forms a unique pool of genetic material.
42
What is the scientific naming convention for species called?
Binomial nomenclature
## Footnote
It consists of a generic name and a specific name.
43
What are the two parts of a scientific name?
Generic name and specific name
## Footnote
The generic name is capitalized, while the specific name is not.
44
What is a taxon?
A named group of organisms that is sufficiently distinct to be assigned to a category
## Footnote
Taxa show high degrees of similarity and are presumed to be closely related.
45
What does it mean for a group to be monophyletic?
All members have descended from a single ancestral species
## Footnote
Monophyletic groups must include all descendants of the originating ancestor.
46
What is a paraphyletic group?
A group that does not include all descendants of the originating ancestor
## Footnote
Example: Invertebrates, as they exclude vertebrate descendants.
47
How many phyla do invertebrate animals currently belong to?
At least 23 phyla (32 phyla in this textbook)
## Footnote
Each phylum represents a unique body plan.
48
What is the percentage of species contained within the phylum Chordata?
About 5% of all described species
## Footnote
This phylum includes both invertebrates and vertebrates.
49
What is the significance of the year 1998 in taxonomy?
A group of influential biologists proposed replacing the Linnaean system with The PhyloCode
## Footnote
The PhyloCode is rank-less and hierarchical.
50
What is a key criticism of the Linnaean system according to some biologists?
Taxon names are unclear in meaning and provide unstable group-name associations
## Footnote
This critique emphasizes the need for more stable classifications.
51
What is the ideal taxonomic classification scheme supposed to reflect?
Degrees of phylogenetic relatedness
## Footnote
Ideally, each grouping should be monophyletic.
52
What challenge is associated with determining evolutionary relationships among major animal groups?
Deciding how best to arrange and sort evolutionary connections
## Footnote
Issues include which characters to use and how to assess accuracy.
53
What do analogous features indicate in evolutionary biology?
They resemble each other but do not indicate a close evolutionary relationship
## Footnote
Example: The eye of an octopus and that of a human.
54
What is the significance of molecular studies in taxonomy?
They allow examination of genotypic diversity directly
## Footnote
Molecular analyses include DNA sequences, protein structures, and ribosomal RNA.
55
What does the polymerase chain reaction (PCR) enable in biological research?
The generation of many copies of specific DNA sequences for analysis
## Footnote
This technique has revolutionized molecular biology.
56
What are Hox genes and why are they significant?
Genes that play a crucial role in the development of body plans
## Footnote
Studies of Hox genes have provided insights into evolutionary relationships.
57
What can cause changes in taxonomic classifications?
New data or discoveries can lead to disagreements about relationships
## Footnote
This is evident in the classification of recently discovered phyla.
58
What does it mean if a character state is described as derived?
It is an advanced condition that evolved from the original state
## Footnote
The original state is referred to as primitive or plesiomorphic.
59
What are the two major clades discussed in the text?
Ecdysozoa and Lophotrochozoa
## Footnote
Also called the Spiralia.
60
What types of gene sequences support the ecdysozoan and lophotrochoan clades?
Hox gene, myosin gene, and large subunit rRNA gene sequences
## Footnote
These are referred to as signature sequences.
61
What can affect the classification of animals within the taxonomic hierarchy?
Studies of early development and fossil record data
## Footnote
These can reveal new information and affiliations among organisms.
62
True or False: The classification of an animal into a taxonomic group is a fixed event.
False
## Footnote
It is a work in progress and can change with new data.
63
What is one limitation of molecular studies in phylogenetics?
They cannot resolve the order of divergence when species diversified too rapidly
## Footnote
Molecular studies also cannot provide details about ancestral unfossilized animals.
64
What is homology in evolutionary biology?
Morphological features that share a common evolutionary origin
## Footnote
Examples include the cranium of humans being homologous with that of other vertebrates.
65
What is the significance of recognizing homology?
It helps in solving evolutionary puzzles
## Footnote
If traits are homologous, they indicate closer evolutionary relationships.
66
Fill in the blank: Evolutionary systematics has been practiced for over ______ years.
100
67
What is an example of a paraphyletic group?
Reptilia
## Footnote
It excludes birds and mammals, which are descendants of the same ancestor.
68
What does the term 'apomorphy' refer to?
Any derived or specialized character
## Footnote
It is of no use in discerning relationships among descendants.
69
What statistical technique is used to infer the reliability of a phylogenetic hypothesis?
Bayesian inference
## Footnote
It uses statistical methods to assess the probability of phylogenetic trees.
70
What is 'bootstrapping' in the context of phylogenetics?
A technique for evaluating the reliability of branches in a phylogenetic tree
## Footnote
It involves resampling data sets to create new datasets.
71
True or False: Molecular studies often support previous conclusions based on morphology.
True
## Footnote
However, they may also propose very different relationships.
72
What does the term 'anagenesis' refer to?
Change occurring within a lineage
73
What is the ancestral (primitive) state?
The character state exhibited by the ancestor from which current members of a clade have evolved
## Footnote
Also called the plesiomorphic state.
74
What does the presence of wings in stick insects suggest about their evolution?
Wings appeared at least four times independently
## Footnote
This indicates complex evolutionary pathways.
75
What is the impact of molecular studies on understanding invertebrate relationships?
They are dramatically altering our understanding
## Footnote
This includes analyses of entire genomes.
76
What is the role of evolutionary systematists?
To wrestle with issues of homology and decide which characters hold the most phylogenetic information
## Footnote
They categorize species based on these analyses.
77
What is bootstrapping in phylogenetics?
A technique for evaluating reliability by creating new datasets through random resampling with replacement.
78
What does a bootstrap value indicate?
The percentage of resamplings that recover a particular branching pattern.
79
Define clade.
A clade is a group that includes an ancestor and all its descendants.
80
What is monophyletic taxon?
A group of species that evolved from a single ancestor and includes all descendants.
81
What is the significance of homologous characters?
They have the same evolutionary origin from a common ancestor and are crucial for determining evolutionary relationships.
82
What is homoplasy?
The independent acquisition of similar characteristics from different ancestors through convergence or parallelism.
83
What does jackknifing evaluate?
The reliability of a branch of a phylogenetic tree by deleting some percentage of information randomly.
84
What is a node in a cladogram?
A branching point representing a common ancestor of the descendant groups.
85
What is the role of an outgroup in cladistic analysis?
To root the tree and imply the direction of evolutionary changes.
86
What is parsimony in cladistics?
The principle that one should accept the least complex scenario in the absence of other evidence.
87
Define pleisiomorphy.
An ancestral or primitive character.
88
What is a polyphyletic grouping?
An incorrect grouping containing species that do not share the same immediate ancestor.
89
What is saturation in phylogenetics?
A situation where the phylogenetic signal is largely lost due to excessive base-pair substitutions.
90
What is synapomorphy?
A derived character shared by two or more species that defines their most recent common ancestor.
91
What is cladistics?
An approach to deducing evolutionary relationships based on shared derived characteristics.
92
What does polarity refer to in evolutionary biology?
The direction of evolutionary change.
93
How are phylogenies constructed in cladistics?
Using synapomorphies and sophisticated computer programs.
94
True or False: A clade can be considered valid if it does not include all descendants of a common ancestor.
False.
95
Fill in the blank: The principle of _______ states that the simplest explanation is preferred.
parsimony
96
What are sister groups?
Two groups of organisms that are descended from the same ancestor.
97
What is the significance of molecular data in cladistics?
Molecular data can provide more reliable insights into evolutionary relationships.
98
What does the term 'derived state' refer to?
An altered state modified from the original or ancestral condition.
99
What does the term 'character states' refer to?
The specific conditions or forms of a character in organisms.
100
What is the main advantage of cladistic methodology?
It accommodates molecular data.
## Footnote
Molecular data provide potential information about evolutionary relationships based on homologous gene sequences.
101
What do identical bases at positions in a gene sequence represent?
They offer no phylogenetically useful information.
## Footnote
Differences in bases indicate separate evolutionary events.
102
In the context of gene sequences, what does a mutation represent?
An evolutionary event.
## Footnote
A mutation can occur in the immediate ancestor or in the ancestor of other groups.
103
What is necessary for proper comparison of gene sequences?
Sequences must be aligned correctly.
## Footnote
Misalignment can lead to comparing non-homologous bases.
104
What happens if there is an insertion or deletion in a gene sequence?
It must be adjusted for to ensure proper alignment.
## Footnote
Failure to adjust for these changes results in inaccurate comparisons.
105
What is a major appeal of cladistics?
The methodology and data are completely transparent and open to examination.
## Footnote
This allows for critical scrutiny and fosters a democratic approach to analysis.
106
True or False: Molecular data evolve at the same rate across all animal groups.
False.
## Footnote
Different molecules evolve at different rates within the same animal groups.
107
What is the significance of the fossil record in evolutionary studies?
It provides physical evidence that can resolve controversies about evolutionary relationships.
## Footnote
For example, fossilized insects with biramous appendages settled debates about insect and crustacean ancestry.
108
How are animals classified based on habitat?
They may be terrestrial, marine, intertidal, subtidal, or open ocean creatures.
## Footnote
This classification reflects degrees of ecological similarity rather than evolutionary relationships.
109
Fill in the blank: Animals that are capable of locomotion are classified as _______.
[mobile]
110
What types of feeders are there based on how animals consume food?
* Herbivores (plant eaters)
* Carnivores (flesh eaters)
* Suspension feeders
* Deposit feeders
## Footnote
Each type reflects different feeding strategies.
111
What is a mutualistic relationship?
A symbiotic relationship where both symbionts benefit.
## Footnote
Examples include relationships between sea anemones and hermit crabs.
112
Define ectosymbionts.
Organisms that live near or on the body of another participant in a symbiotic relationship.
## Footnote
Ectosymbionts can influence the feeding biology of their hosts.
113
What is the difference between commensalism and parasitism?
* Commensalism: One symbiont benefits, the other is neither helped nor harmed.
* Parasitism: One symbiont benefits at the expense of the host.
## Footnote
These relationships highlight different dynamics in symbiotic interactions.
114
What is the term for when both symbionts benefit from their relationship?
Mutualism
## Footnote
Mutualism is a type of symbiotic relationship where both parties gain benefits.
115
When one symbiont benefits and the other is neither helped nor harmed, what is this relationship called?
Commensalism
## Footnote
The benefiting member in a commensal relationship is referred to as the commensal.
116
What defines parasitism in terms of the relationship between the parasite and its host?
Metabolic dependence of the parasite on the host
## Footnote
Parasitism is characterized by the parasite's reliance on the host for survival, often at the host's expense.
117
True or False: A parasite may impair the host's activities.
True
## Footnote
While some parasites may not significantly harm the host, many do affect the host's functions.
118
What happens to the classification of a parasite that eventually kills its host?
It becomes a predator
## Footnote
This illustrates the blurred lines between different types of ecological relationships.
119
Fill in the blank: The essence of _______ is that the parasite is metabolically dependent upon the host.
parasitism
## Footnote
This dependency is what distinguishes parasitism from other forms of symbiosis.
120
What complicates the tidy categorization of animals into mutualism, commensalism, and parasitism?
Transitional forms
## Footnote
Transitional forms often exhibit characteristics of multiple types of relationships, making strict classification challenging.
121
How do definitions of mutualism, commensalism, and parasitism change over time?
They are modified by various workers
## Footnote
Changes in definitions occur in an effort to better fit observed relationships.
122
What is a common characteristic of transitional forms in ecological relationships?
They evolve from one type of relationship to another
## Footnote
This evolution can blur the lines between distinct categories.
