Bio 1780 Prelim 2 Review Flashcards
Is the gametophyte or sporophyte more dominant in mosses? and ferns?
moss: gametophyte, ferns: sporophyte
What is found in fungi cell walls?
chitin
Why are red algae red? Does it mean they don’t have chloroplast?
They have an accessory pigment phycoerythrin, they have chloroplasts with chlorophyll-a
What is found in the cell wall of glaucophyte chloroplasts and what is its significance?
and what is its significance?
a. Peptidoglycan, evidence of endosymbiosis of cyanobacteria
How do fungi acquire nutrients? explain the process
Absorptive heterotrophy: hyphae secrete digestive enzymes and processed nutrients are then absorbed
What are some problems land plants had to overcome and what structures did they develop to overcome
them?
support - sprawl on ground or have trunk; avoid dessication - stomata; access to water - vascular systems; spreading gametes - shape of seeds
What is lichen?
symbiotic relationship b/w fungi (usually ascomycetes) and a photosynthetic partner (either cyanobacteria or
green algae)
What is the fitness of an individual measured as?
The number of offspring it produces in its lifetime compared to the average individual in its population
What is Hardy-Weinberg equilibrium? What is the formula and what do we use it for?
p
2
+ 2pq + q2
= 1, p + q = 1. Used as null model if no evolution is present
Define the Bottleneck effect and predict its outcome
Sudden external factor (e.g. natural disaster) that kills most of the individuals in a population, only leaving a
randomly selected small group of individuals. Genetic drift will cause it to evolve from the previous genotypic
frequencies
What does Heterozygosity depend on? How do they each affect the degree of heterozygosity?
Mutation & population size. Increase in both mutation rate and population size will increase heterozygosity
For what reason might an advantageous allele have trouble coming to a “fixed” frequency in a population?
What conditions would cause it to do so quickly and easily?
recessive allele advantage = hard to fix b/c hard to get enough homozygous recessive to show effect, dominant
allele fix quickly b/c it’s effect is not shielded
What is genetic drift? When is it more important?
chance deviations in allele frequency over time resulting in evolution but without natural selection or adaptation; small populations
Why do advantageous alleles that are co-dominant fix faster than those that are dominant?
heterozygous individuals have distinct phenotypes and so its recessive alleles can be selected against more
efficiently than if heterozygous indv exhibit dominant phenotype and shield the recessive allele
What is secondary contact? What are the possible outcomes of it?
When extrinsic barrier disappears and populations allowed to mate. speciation now depends on intrinsic
barriers.
b. Outcome 1: hybrids equally/more fit than parental - species will merge.
c. Outcome 2: hybrids less fit in parental ranges but equally/more fit in hybrid zone, then stable hybrid zone
will form.
d. Outcome 3: Hybrid less fit everywhere relative to parental, natural selection will reinforce reproductive
isolating mechanisms and speciation occurs
Outcome when hybrids equally/more fit than parenta
species will merge.
Outcome when hybrids less fit in parental ranges but equally/more fit in hybrid zone
stable hybrid zone
will form.
Outcome when Hybrid less fit everywhere relative to parental
natural selection will reinforce reproductive
isolating mechanisms and speciation occurs
What is reinforcement and what does it accomplish?
When hybrid offspring are unfit and natural selection reinforces reproductive isolation mechanisms,
changing postzygotic isolation to prezygotic isolation
Glaucophytes
Unicellular aquatic photosynthetic organisms, some with flagella; Chloroplast derived from primary endosymbiosis and retains peptidoglycan (from cyanobacterial cell wall) between inner and outer membrane
Red algae
Reddish accessory photosynthetic pigment masks green chloroplasts in low light; marine, multicellular, often attach by holdfast; Secrete calcium carbonate, enhance formation of coral reefs
“green algae”
Unicellular, colonial, multicellular • Two kinds of chlorophyll, store photosynthetic products as starch; Among green plants, “green algae” are basal to land plants
liverworts
Simplest land plants, small leaf-like sheets of tissue as the visible organism, attach by hair-like rhizoids;Terrestrial but very moist circumstances
mosses
Larger, more complex than liverworts—stomata, dead cell tubes for transport;Moist terrestrial habitats, form lush mats; Decaying layers in water form peat bogs
microphyll
small leaf with single unbranched vein; originally formed from little outgrowths of sporangia, spore making structures
megaphyll
big leaf with multiple branching veins; leads to evolution of true leafy structures
ferns
Megaphylls with stomata, xylem, and phloem—terrestrial but moist quiet habitats (lack strong support) • Spores airborne, gametes by water
synapomorphy of green plants
chlorophyll b; starch storage
green plants
green algae + land plants
synapomorphies of vascular plants
have systems to transport food and water throughout plant; microphyll and megaphylls; stomata
plant tree
Plantae Glaucophytes (un-named taxon) Red algae Green Plants “Green algae” Land plants “Basal land plants” Vascular plants Ferns Seed plants
green plant with protected embryo but no seeds
liverworts, mosses, ferns
Population genetics
evolutionary processes within populations over small time scales
evolution
any genetic change in a population over time
genetic change may occur through
mutation, migration, genetic drift, natural selection
population
group of interbreeding individuals
mutation
any heritable changes to DNA
Evolution requires
genetic variation in the population
polymorphisms
mutations that are segregating in a population; give evolutionary advantage, an evolutionary disadvantage, or have no effect at all
every human, every generation, there are _____ mutations
10
in entire world
every nucleotide is mutated every gneeration
evolution
any change in allele frequency in a population over time
gene
a genetic locus coding for a functional RNA transcript; almost always codes for protein
locus
any defined segment of DNA; may not code for proteins
polymorphic
locus is polymorphic if it has 2 or more alleles
phenotype can be determined by
genotype or environmental conditions; combination of both
Gene pool
all the gene copies present in a population (2 per diploid individual, therefore 2N total for a population size N)
allele frequency
number of one allele (2 x AA + Aa) /total number of alleles (2 x (AA + Aa + aa)
How does drift affect smaller populations
o Higher probability of large frequency jumps in any given generation
o Shorter expected time to fixation or loss
