Lab Exam #1 Flashcards
What does a proper figure caption consist of?
- figure #
- name of the organism (with genus-species name underlined)
- some indication of classification (phylum at minimum)
- how the specimen was prepared (e.g. whole mount, wet mount, prepared slide)
- orientation of specimen if appropriate (dorsal, ventral, etc.)
- how the specimen was viewed (e.g. compound light microscope, dissecting microscope, directly viewed)
- drawing magnification (not the objective lens)
How do you calculate drawing magnification?
DM = size of drawing/actual size of specimen
What is the ocular unit for 4x objective lens?
0.026mm
What is the ocular unit (mm) for 10x objective lens?
0.01mm
What is the ocular unit (mm) for 40x objective lens?
0.0026mm
What is the ocular unit (mm) for 100x objective lens?
0.001mm
What is the order of hierarchy when classifying a species?
- domain
- kingdom
- phylum
- class
- order
- family
- genus
- species
Define taxon
a taxonomic group of any rank, such as a species, family, or class.
-plural: taxa
Define branch and node
Branch: the line connecting each taxon in a phylogeny
Node: the point where two or more branches connect
Define a symbiotic relationship
involving interaction between two different organisms living in close physical association.
- mutualism
- commensalism
- parasitism
What is descent with modification?
Darwin’s proposed idea that species change over time, give rise to new species, and share a common ancestor
Define population
a group of individuals of the same species living and interbreeding within a given area.
Define Phenotype
the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
Define random mutation
the expression of mutations is random, not in a preplanned pattern.
Define adaptive evolution
to evolutionary changes in an organism that make it suitable to its habitat. The changes result in an increased chance of survival and reproduction. The changes enable the particular organism to fit to an environment.
Define microevolution
Small-scale evolutionary changes in allele frequencies within a population or species.
- typically observed over short periods of time
- can be reversible
Define macroevolution
A process where evolutionary events result in the creation of a new species or taxonomic group, one that is distinct from the original “parent” form.
- observed over a long period of time
- populations are no longer able to reproduce with ancestral organisms
What are the three criteria that must exist in order for evolution via natural selection to occur? Define each.
- Variation - differences of traits in individuals
- Heritability - genes are passed from parents to offspring (DNA)
- Reproductive Advantage - certain traits give more reproductive success.
What do adaptations lead to?
An increase in fitness and functioning of the individual in relation to its environment
Define selective pressure
external agents which affect an organism’s ability to survive in a given environment.
Define structural adaptations
traits such as body shape, type of appendages or fur color.
Define behavioral adaptations
changes in the manner in which an organism behaves to deal with environmental pressures, such as making food caches, sleeping underground, or calling to maintain group coherence.
Define physiological adaptations
traits that are part of an organism’s phenotype because they represent the biological function of some anatomical feature.
-sometimes not visible to an observer
What phylum do sea stars belong to?
Phylum Echinodermata
What does the body wall of a sea star consist of? Define each
- epidermis - body covering on all surfaces of sea star
- endoskeleton - consists of dermal ossicles (calcareous structures embedded in epidermis) and calcareous spines (projecting outward from the surface)
What does the oral surface of a sea star consist of? Define each
Oral surface - the underside (which normally faces the substratum to which the sea star is attached) of the sea star.
Consists of:
- mouth - located in the center of the oral surface
- tube feet (podia) - contained within grooves along each arm
What does the aboral surface of a sea star consist of? Define each
Aboral surface - the surface of the sea star that is typically exposed
- Eyespots (sensory discs) - found at the tips of each arm with a terminal tentacle
- Madreporite - distinct circular structure just off center from the aboral axis
- Dermal branchiae - thin bladder like structure, extending through the body wall from the coelom (these respiratory exchange surfaces are filled with fluid from the body cavity, and can be retracted if anything disturbs the surface of the sea star)
What are a sea star’s pedicellariae?
2 or 3-piece pincers found scattered randomly over the external surface of the epidermis
What is the coelom?
the fluid- or air-filled body cavity that separates the digestive tract from the endoskeleton body covering
What does a sea star’s digestive system consist of? define each
- pyloric ceca - paired digestive glands, located aborally in the arms
- pyloric stomach - thin-walled, star-shaped sac located on the aboral side of the cardiac stomach.
- cardiac stomach - 5-lobed, muscular stomach, oral to the pyloric stomach; everted during feeding
What des a sea star’s reproductive system consist of? define each
- Gonads - paired reproductive structures occupying the floor of the body cavity in the proximal region of each arm; the members of each pair of gonads extend into adjacent arms.
What does a sea star’s water vascular system consist of? define each
- stone canal - a whitish, slender tube extending orally down from the madreporite
- ring canal - embedded in the bony ossicles surrounding the mouth.
- radial canal - extends down each arm from ring canal
- lateral canals - extend from radial canals to connect with the tube feet
- ampullae and podia (tube feet) - are viewed externally in the ambulacral groove and the rounded ampullae can be seen internally on the ambulacral ridge
What are the dermal ossicles used for and how is it adaptive?
Protection and support
- protects the sea star from predators and rough conditions in tidal areas.
- internal support (endoskeleton)
What are the dermal branchiae used for and how is it adaptive?
Aid in respiration
-allows for respiration to occur in an aquatic environment
What are the pedicellariae used for and how is it adaptive?
Removal of parasites
- keeps parasites away that can cause harm
- disadvantageous (parasites)
- increases fitness
What are the pyloric ceca used for and how is it adaptive?
Digestion and storage (digestive glands)
-provide a place to store food because prey isn’t always guaranteed.
What is the cardiac stomach used for and how is it adaptive?
Feeding
-can be everted out of their mouth, which allows them to eat and externally start digestion
What is the madreporite used for and how is it adaptive?
External opening of water vascular system
-filters water to prevent debris from entering the water vascular system
What are the tube feet (ampullae and podia) used for and how is it adaptive?
Locomotion and feeding
-withstand the pressure of the tide (flat and spread out)
What is the ambulacral ridge used for and how is it adaptive?
Protection of the radial canal
-the water vascular system tubes need protection to ensure they stay intact.
Define plesiomorphic
a structure that is ancestral, meaning it is found in the earliest member of an evolutionary lineage
Define apomorphic
a structure that is derived, meaning it is found in later members of the lineage.
-derived is changed from the ancestral form
What are synapomorphies?
Shared, ancestral character states
Define homologous structures
structures that are similar in different organisms because of a shared ancestry
-they result from divergent evolution
Define analogous structures
Structures that perform the same function without being present in a common ancestor
Define sister taxa
groups that share a common ancestor and are more related to each other than to other groups
Define parsimony
the principle we use to decide between several hypotheses. It assumes that the simplest interpretation of all available data is likely the correct explanation.
Define cladistics
a method of determining evolutionary relationships by analyzing the features they share
Define convergent evolution
the independent development of similar traits or features (as of body structure or behavior) in unrelated or distantly related species or lineages that typically occupy similar environments or ecological niches
Define reversals
Arise when a lineage has exhibited a derived character at some point in its evolutionary history but that character reverts to an ancestral state
Define homoplasy
the collective name for a series of conditions (such as convergences and reversals) that violate the assumptions of cladistic analyses
Define monophyletic groups (clades)
groups that contain the most recent common ancestor and ALL of the descendants.
Define polyphyletic
when your tip taxa appear on separate branches that are not connected to a common ancestor
Define paraphyletic
when you leave out some of the descendants of the common ancestor
What is coded as 1 and 0 in a data matrix?
0 = character state shown by the outgroup
1 = character states that differ from that of the outgroup
Define a photoautotroph
an organism that carries out photosynthesis
Define heterotrophy
an organism deriving its nutritional requirements from complex organic substances.
Define mixotrophy
Those that combine autotrophy (self-sustaining food production from a carbon source and inorganic nitrogen) and heterotrophy (ingesting other organisms to acquire carbon) are known as mixotrophs.
