UNIT 5 - Evolution and Biodiversity Flashcards
List the three main domains
- prokaryotes - bacteria
- extremophiles - archaea
- eukaryotes
Distinguish the three main domains based on the presence of introns
bacteria - rare/absent
archaea - present in some genes
eukaryote - frequent
Distinguish the three main domains based on the presence of histones associated with DNA
bacteria - absent
archaea - proteins similar to histones bound to DNA
eukaryote - present
Define evolution
process by which living organisms are formed by gradual change frm previous organisms
in other words process of cumulative change in the heritable characteristics of a population
Define and state an alternative name for artificial selection
process by which all the plants and animals used by humans have been developed from wild species by selecting individuals with desirable traits and breeding from them
selective breeding
Define a fossil
remnant of past life uncovered from the crust of earth
List the main ways of gaining evidence for evolution
- study of fossils
- artificial selection in the production of domesticated breeds
- study of the comparative anatomy of groups of organisms
State the characteristics of homologous structures
- similar in fundamental structure
- similar in position and development but not necessarily in function
- similar because of common ancestry
State the characteristics of analogous structures
- resemblance in function
- differing in fundamental structure
- illustrating only superficial resemblances
Define natural selection
the mechanism by which better adapted organism survive to produce a greater number of viable offspring which has the effect of increasing their proportion in the population so that they will become more common
Define analogous structures
similar in structure but different in evolutionary origin
Define neo-darwinism
an essential restatement of the concepts of evolution by natural selection in terms of mendelian and post-mendelian genetics
State an example of a homologous structure
limbs of vertebrates
all of which appear to be modifications on the ancestral five-fingered limb
State an example of analogous structure
wings of birds and insects
similar only in their function as areofoils
State the ways of arising the gene for antibiotic resistance
- spontaneous mutation
- conjugation
- infection by a virus that has picked up the gene for antibiotic-resistance in another host
Define adaptive radiation and give an example of it
rapid evolutionary diversification of a single ancestral line
e.g. beak types seen in the finches of the Galapagos islands which have specialized beak shapes depending on their primary source of nutrition
Define an autopolyploid
individual that has more than two chromosome sets that are all derived from a single species
State reasons for the rapid evolution of multiple antibiotic resistance in the last few decades
- widespread use of antibiotics both for treating diseases and in animal feeds used in farms
- rapidly reproducing bacteria
- huge populations of bacteria with increasing chance of mutations
Define a gene pool
different genes in an interbreeding population at a given time
Define and state the reason for overproduction of offspring
organisms produce many more offspring than survive to be mature individuals which in the wild leads to their competition for resources
the majority of organisms fail to survive and reproduce as they are limited by environmental factors
Define species
a group of potentially interbreeding populations with a common gene pool that is reproductively isolated from other species
State the two forms of polyploidy
- autopolyploid
- hybrid offspring
State the reasons for evolution to occur
- mutations introducing new alleles
- selection pressures favoring the reproduction of some varieties over others
- barriers to gene flow
Define allele frequency
frequency of a particular allele as a proportion of all the alleles of that gene in a population
Define a geographic isolation of the populations
separation of the two populations by geographic barriers such as rivers, mountains or oceans
State the ways of reproductive isolation of populations
- temporal
- behavioral
- geographic
State the two types of speciation
- sympatric
- allopatric
Define allopatric speciation
a physical barrier separates a species into geographically isolated populations which then develop independentently under the different conditions and eventually become unable to interbreed
Define sympatric speciation
a gene pool can become divided without the population being geographically split
Define temporal isolation
a form of reproductive isolation caused by differences in breeding schedules
Define behavioral isolation
presence or absence of a specific behavior prevents reproduction from taking place
Define polyploidy
accidental origination of specie during cell division resulting in extra sets of chromosomes
Define hybrid offspring
form of polyploidy occurring when two different species interbreed
most such hybrids are sterile
State the reason for a hybrid offspring being sterile
the set of chromosomes from one species cannot pair during meiosis with the set of chromosomes from other species
Define an allopolyploid
a fertile polyploid of a sterile hybrid
State the three models of selection
- directional
- disruptive
- stabilizing
Define directional selection
Favours variants that are at one extreme of the distribution
Define disruptive selection
Favours variants at both ends of the distribution
Define stabilizing selection
removes extreme variants from the population and preserves intermediate types
Define phyletic gradualism
evolution occurs by the gradual accumulation of small changes and the intermediate stages of evolution not represented by fossils testifies to the incompleteness of the fossil record
State the two patterns of macroevolution
- phyletic gradualism
- punctuated equilibrium
Define speciation
evolutionary process by which two related populations diverge into separate species
Define punctuated equilibrium
evolutionary history consists of geologically long periods of stasis with little or no evolution interrupted or punctuated by geologically short periods of rapid evolution
State the principle of the binomial system
scientific name of two Latin words
first - generic name - noun - designates the genus
second - specific name - adjective - names the species
examples:
homo sapiens = modern humans
State the principle of naming the closely related organisms
have the same generic name but differ in their species name
Define taxonomy
science of classification of organisms into a hierarchal scheme based on their similar characteristics
Distinguish natural versus artificial organism classification
natural classifies an organism basen on its evolutionary relationships (i. e. kingdom to species)
artificial classification groups organisms which show similar characteristics due to convergent evolution (i. e. all organisms with wings)
State the taxonomic rank starting from domain
domain
kingdom
phylum
class
order
family
genus
species
common name
State with reason the mode of nutrition of an Amoeba
holozoic as it feeds after trapping food in food vacuoles
State with reason the mode of nutrition of a Plasmodium (malarial parasite)
parasitic - feeds on contents of liver cells and red cells
State with reason the mode of nutrition of a Paramecium
holozoic - feeds after trapping food in food vacuoles
State a characteristic feature of the plasma membrane of the Paramecium and Euglena
strengthened by additional protein - a pellicle
State with reason the mode of nutrition of Saccharomyces
saprotrophic - feeds on nectar via fermentation
State the characteristic features of the plantae kingdom
- photosynthetic
- eukaryotic organisms with a wall containing cellulose
- autotrophic - manufacturing sugars by photosynthesis in their chloroplasts
- store starch
- permanent vacuoles
State the principle of a life cycle of plants
two generations/stages
- gametophyte generation producing gametes
- sporophyte generation forming spores
State the four main phyla of green plants
- bryophytes - non-vascular plants
- ferns - seedless plants (but vascular)
- conifers - seed and vascular plants
- flowering plants - seed and vascular plants
State the characteristics of bryophytes
- poorly adapted to terrestrial conditions land plants - damp environments
- stems with radial symmetry
- stems with bilateral symmetry, no lignin
- no true leaves or roots
- no cuticle so no protection from water loss
- reproductive structures - sporangium
State the characteristics of ferns
- well adapted to terrestrial conditions
- leaves with cuticle
- roots non woody stems
- divided leaves
- height up to 20 m
- reproduction through sporangia
State the characteristics of conifers
- trees (100 m), shrubs
- strong stems
- woody (lignin) stems
- waxy narrow needle like leaves
- vascular system (tracheids)
State the characteristics of phylum
- dominant group of land plants
- roots and stems
- leaves
- vascular bundles (xylem and phloem)
- waxy cuticle
- ovules in an enclosed carpel structure
Distinguish between monocotyledons and dicotyledons in terms of seed-leaves and veins in leaves
monocotyledons have parallel veins in their leaves and single seed-leaf in the embryo of the seed
dicotyledons have net veins in their leaves and two seed leaves in the embryo
DICOTYLEDONS
- embryo in seed has 2 cotyledons
- broad leaves with veins forming a network
- vascular bundles of stem in a ring
- branched roots
- parts of the flowers (sepals, petals, etc.) in fours of fives
MONOCOTYLEDONS
- embryo in seed has 1 cotyledon
- bayonet or strap-shaped leaves with parallel veins
- vascular bundles of stem numerous and scattered
- unbranched roots
- parts of the flowers (sepals, petals, etc.) in threes.
State the characteristics of the animal kingdom.
- multicellular, eukaryotic organisms with heterotrophic nutrition
- highly specialized cells (organs usually)
- nervous system present
- bilateral symmetry
State the life cycle of animals
diploid life cycle
with haploid gametes produced by adults in meiosis
Define cephalization
an evolutionary trend in the animal kingdom toward centralization of neural and sensory organs in the head or anterior region of the body
State the six main phyla of non-vertebrates of the animal kingdom
- sponges
- jellyfish and sea anemones
- flatworms
- segmented worms
- mollusk
- jointed-limbed animals
Define and state the characteristics of sponges (the porifera)
simplest multicellular animals, structurally little more than colonies of cells, are aquatic and mostly marine animals
- simple sac-like structures of cells in two layers arranged around a central gastric cavity
- entirely lack nervous system
cells specialize in feeding, structural support or reproduction - can reproduce asexually by budding and sexually forming a free-swimming larva
- no body layers but rather aggregate of different cell types
- no mouth or anus
State the characteristics of cnidaria and give example of such
e. g. jelly fish, corals
- 2 layers of the body plan
- radial symmetry
- single entrance that serving as both cavity for circulating the respiratory gases and nutrients
- secondary consumers - posses nematocysts to disable prey
Define nematocysts
stinging cells with toxins used to disable prey
State the material the skeleton of corals is made of
CaCO3
State the characteristics of Platyhelminthes (the flatworms)
- flat, unsegmented animals
- triploblastic organization
- no cavity in the middle layer but a mouth and a gut present
- no anus
- feeding by scavenging or predating on other small animals
- no circulatory system but ease in diffusing to most cells because of the thin flat body
- flame cells present
- hermaphrodite organization
- this phylum contains many important parasites like tapeworms
Define triploblastic organization
body built from three cell layers
State the function of flame cells in Platyhelminthes
excretion and regulation of water and ions in the body
Define a hermaphrodite organization
both male and female reproductive organs present in one individual
State the specialized characteristic features of a tapeworm.
the head with specialized structures - suckers, hooks, spines, - that hatch on to the intestinal wall
State the characteristic features of the segmented worms (phylum Annelida)
- 3 layers of the body plan
- bilateral symmetry
- hydrostatic skeleton
- cephalization
- metameric segmentation
- ringed segments of the body
- mouth with a gut connected
- anus present and separate
- skin surface for gas exchange - moist body surface
- ventral nerve cord running the length of the body
Define metameric segmentation
each segment of the body contains the same pattern of nerves, blood vessels and excretory organs
State the characteristic features of Mollusca and give an example of such
e. g. snails, limpets, mussels, octopuses
- most aquatic, few terrestrial
- soft, flexible bodies
- little or no segmentation
- usually covered by a shell
- compact body shape means ineffective diffusion for the transport of nutrients thus they have gills or occasionally lungs and a well-developed blood circulation
- rasping, tongue-like radula used for feeding
State the characteristic features of Arthropoda (jointed limbed animals) and give an example of such
e. g. crustaceans, centipedes, insects
- segmented bodies, covered by a hard external skeleton made of chitin and jointed limbs
- exoskeleton doesn’t grow with the animal - molting
- open blood circulation - haemocoel cavity surrounding all the organs and a tubular heart pumping blood into the haemocoel
- ventral nerve cord with nerves running to each segment (concentration of nerves in front of the body)
Define moulting
periodical shedding of an exoskeleton and its exchange for a larger one
Define a clade
a group of organisms believed to comprise all the evolutionary, descendants of a common ancestor
Define cladistics
method of cloudifying living organisms based on the construction and analysis of cladograms
Define a cladogram
evolutionary tree showing points at which clades diverged from a common ancestral form
State where does the evidence come from for a cladogram
biochemical data:
- number of differences in the DNA base sequence of a gene
- number of differences in the amino acid sequence of protein
State the correlation stemming from a cladogram
a positive correlation between the number of differences between two species and the time difference since they diverged from a common ancestor
Define the node and clade in relation to cladogram terms
nodes - the tree branches from the coloured circles - as the tree spits at nodes it indicates when the species have diverged
clade - groups of organisms sharing a common ancestor
Define a molecular clock
differences in the base sequence of DNA is used to deduce how long ago species split from a common ancestor
State the requirement needed for the statement in a dichotomous key
each statement must be qualitative and not relative.
e. g. not “long leaf blade” but “length of leaf blade greater than width”
