01. EVOLUTION & LIFE'S DIVERSITY Flashcards
Outline fission (asexual reproduction)
What: Splitting into 2+ equal parts
When: homogenous, stable environ
Who: all domains/kingdoms
Advantages
o Rapid replication
o Minimal E consumption
o Efficient + secure (X need to find mate)
Disadvantages
o Less genetic div → less able to adapt to changing/new environ
Example: bacteria
Outline budding (asexual reproduction)
What: parent cell div into 2 uneq parts
When: abundant nutrients parent grows too lg
Who: uni + multicell orgs from all domains + kingdoms
Advantages:
o Rapid replication
o Can occur anywhere on parent org (a/t some places more common than others)
Disadvantages:
o Less genetic div → less able to adapt to changing/new environ
Examples: hydra (animal) + yeast (fungi)
Outline fragmentation (asexual reproduction)
What: frag of parent org breaks off forms new org
When: w/ intention or stimulated by changing/new environ cond
Who: multicell orgs from all euk kingdoms
Advantages
o E efficient bc a) X have to find mate b) X need to devt sex orgs
o Secure bc X have to find mate
o Genetic clone → favourable traits retained
Disadvantages
o Less genetic div → less able to adapt to changing/new environ
Examples: planaria (flatworm)
Outline vegetative propogation (asexual reproduction)
What: part of parent plant used to grow new plant – via multi strats: runners, bulbs, tubers, suckers
When: when reprod orgs have devt + sep from other orgs (e.g. axillary bud grows + seps from lateral shoot devts indiv roots)
Who: multicell plantae orgs only
Advantages:
o E efficient bc a) X have to find mate b) X need to devt sex orgs
o Secure bc X have to find mate
o Genetic clone → favourable traits retained
Disadvantages
o Less genetic div → less able to adapt to changing/new environ
Examples: strawbs, garlic, potatoes
Outline parthenogenesis (a/sexual reproduction)
What: unfertilised egg devt into indiv (mostly remains dip org bc fertilised by mum thru reabsorbtion)
When: male X present
Who: multicell orgs from euk kingdom Animalia
Advantages:
o E efficient + secure bc X have to find mate
Disadvantages:
o Less genetic div → less able to adapt to changing/new environ
Examples: bees, ant, some fish/lizards
Compare the key features of asexual and sexual reproduction
Asex:
* req one parent org
* offspring = genetically identical to parent
* time/energy eff
* pop inc rapidly when conditions = optimal
Sexual:
* req two parents orgs
* offspring = hybrid of parents’ genes
* req time/energy to find mate
* inc genetic div -> inc pop resilience bc inc variation w/in pop that NS can act upon
Outline features of alternations of generations
- occurs in multicell protists, all land plants, some fungi
- alt bw hap + dip gens = both multicell
- dip form prod spores → hap form prod gametes
- gametes need to fuse w partner gamete to reprod vs spores don’t
Outline features of sexual reproduction in fungi
- process varies dep on species
- maj time in hap phase
- 3 stages = plasmogamy, karyogamy, meiosis
Outline features of reproduction via pollination
- 2 types = biotic + abiotic
- abiotic factors = wind, rain, water e.g. cedar tree, water plants
- biotic = attracts pollinators e.g. orchids scent mimic fem bees
Outline features of reproduction in angiosperms
stamen structures house sperm = contain genetic info
Draw a diagram of a generalised plant life cycle
Image 1
Why do organisms respire?
to release energy from food → fuel cell function
What is the difference between anaerobic and aerobic respiration?
aer resp uses O to extract E from food - anaer uses diff compound e.g. nitrate, sulfur instead
What are the benefits of aerobic + anaerobic respiration?
aerobic: release more ATP molecules → possibly enabled evolution of multicellularity + lg size orgs
anaerobic: releases E quickly + can occur in low O environs
Why is fermentation not considered respiration?
X use electron transport chain
How did respiration evolve?
early life respired anaerobicly bc X much O in atm
h/e emergence of photosynthetic bacteria ~3.5bn yrs ago created cond conducive for aerobic resp ~2.9bn yrs ago
What types of respiration (aerobic or anaerobic) do bacteria and fungi use?
bacteria = aer and/or anaer
fungi = mostly aer but occ anaer
How do fungi obtain oxygen in soil?
oxygen in tiny air spaces bw soil particles absorbed thru thin outer wall of hyphae (thin branching filamentous structure)
How are bacteria and fungi used to create food?
bacteria + fungi = core components of fermentation process = breaks down bacteria/yeast into starch/sugar
Why do all parts of the plant need to respire?
minimal gas exchange between parts - need to fulfill own resp needs indiv
How do plants obtain oxygen?
via diffusion thru stomata and lenticels
via absorption thru roots
How have plant roots adapted to meet respiration needs?
- aerial roots (pneumatophores)
- aerenchyma = sml air pockets w/in plant tissue → enabled oxygen flow from exposed to anoxic/waterlogged portion
How do stomata facilitate respiration?
open/close to allow gas exchange dep on environ factors - also dets stomata density/aperture
What are some different types of gas exchange in animals?
- direct diffusion
- integumentary exchange (across skin)
- trachea
- gills
- lungs
often depends on moisture lvl of environ e.g. integ exchange X conducive to dry environ bc skin X wet
What are the four possible stages of respiration in animals?
- breathing
- gas exchange
- circulation
- cellular resp
not all animals use all 4
Why do surfaces need to remain wet for gas exchange?
gasses must first diffuse into liquid before diffusing across the membrane
Features of direct diffusion
- used by sml animals <1mm e.g. flatworms
- ox diff across outer membrane → supply ox to cells
- X option for lg animals bc diff ≠ quick enough
Features of integumentary exchange
- used by animals in moist environ e.g. earthworms + amphibians
- skin = gas exchange surface
- sim to dir diff but instead diff across integument (skin) into circulatory system → supplies O around body
Why do insects respirate via trachea?
exoskeleton = impermeable to gasses
Features of trachea
- system of tubes branching across body w/ openings (spiracles) → can open/close
- some insects use muscle contractions or extended tracheal branches to ventilate tracheal system
- seperate from circ system
Features of gills
- used by molluscs, annelids, crustaceans + fish
- located in cavity or externally
- highly branched + folded skin tissue
- O from water diff across gills → circ system/coelomic fluid
- countercurrent system commonly facilitates O gain + CO2 loss
Features of lungs
- used by amphibians, birds, reptiles + mammals → differs greatly
- amphibians → sac-like lung
- reptiles → sac-like or subdiv
- mammals → branching lungs that end in sml air filled sacs (alveoli)
- birds → parallel series tubes (parabronchi)
Why is food so important for life?
- maintain normal cellular function + replication INDIV SURVIVAL
- reproduce SPP SURVIVAL
What is the key distinguishing feature between autotrophs and heterotrophs?
autotrophs can synthesise their own food vs heterotrophs cannot
What is the functional difference between an autotroph and a heterotroph?
heterotrophs must consume other forms of life
Why are all species of animals and fungi heterotrophs?
Animals + fungi X synthesise their own food
Why have scientists concluded that the earliest form of life was a heterotroph?
earliest life forms = unicell + resemble modern-day bacteria → fed thru absorbing acid + base mols from org oceans ⇒ t/f heterotrophs
Describe endosymbiotic theory
- oxygenic photosynth evolved ~2.7bn yrs ago in bact sim to modenr cyanobact → early euk cells engulged photosynth bact thru endocytosis → created 1st plant cells
- explains evol of eukaryotes from prokaryotes
Examples of endosymbiosis
endosymb= when one org lives inside another
e.g. euk cells absorb plastids - PT resp w/in euks
Evidence to support conclusion that chloroplasts originated from photosynthesising bacteria?
chloroplasts = phylogenetically related to cyanobact
Why are autotrophs so important?
prim prod of org E for all other orgs
esp. chemoautotrophs - lived in hostile environs (low sunlight) → prim producers in these ecosystems
How are heterotrophs subdivided?
depends on what they eat
- carnivores → animals
- insectivores → insects
- herbivores → plants
- omnivores → meat, plants, fungi etc.
- scavengers → remains left by carnivores + herbivores
- detritivores → soil, leaf litter + other decaying org matter
Why are heterotrophs so important?
prim, sec + tertiary consumers of org matter
What is the key difference between a chemoautotroph and a photoautotroph?
diff source of inorg E for synthesisation of org comps
What is a chemoautotroph?
- bacteria
- synth own org mols fuelled thru oxid of inorg compounds
- thrive in hostile environs
- critically imp in hostile ecosystems bc prim producers of org E here
What is a photoautotroph?
- organism that prod all req org mols from inorg mols, fuelled thru sunlight e.g. photosyhthesis
Why do algae require damp or moist conditions for survival?
X possess any water-absorbing/water-conducting structures for desiccation
Why are the largest algae extremely thin?
allows nutrients to pass easily thru cell walls
Name three of the key adaptations land plants have evolved.
- roots to extract water + dissolved nutrients from soil
- vascular tissue for transp water + nutrients
- diversity of leaf types + size for PS
What features of roots make them so important for land plants?
- facilitate nutrient + water uptake from soil
- provide structural support + anchorage
- synthesise plant hormones
- house nutritional reserves
Why did leaves evolve?
inc SA for PS + gas exchange → adapted to capture O according to environ factors/ecological niche
Ways heterotrophs feed.
- diffusion + phagocytosis
- diff = nutrients move across cell membrane
- phagocytosis = specialised structures + cells engulf food/prey
- useful for sml + uncomplex species
- filter feeding
- straining org matter/food parts from water thru spec filtering structure
- paratisism
- feed from other species X kill them
- X prov benefit in return
- energy eff BUT entirely dep on host
- e.g. tapeworm, jawless fish
Why is filter feeding not effective on land?
air X allow for cont org matter/food particle flow involved in FF
Why might have insect mouthpart diversity evolved?
- insects spend disprop portion lifespan as juveniles → gather resources to reprod as adults
- t/f mouthpart div evolved to maximise extraction of resources from prey of specific environ
Would you expect a bearded dragon (reptile) to have homodont or heterodont dentition?
homodontic bc reptiles = non-mammalian invertibrates
What are the differences between excretion, elimination, and respiration?
excret = removal of bodily waste products vs elim = removal of unabsorbed food that never part of body vs resp = exchange of gasses
What are the differences between passive and active transport?
- passive = common in bact, fungi + some aquatic plants vs active = common in animals
- passive relies of diff + osmo vs active speeds up process bc involves specialised cells/organs
How do guard cells operate in plants?
guard cells swell when in high water availability and shrink in low water availability to encourage/prevent water aquisition/loss thru transpiration
Why do larger species require more complex excretory mechanisms?
need more efficient/resilient system than relying on passive forms (diff + osmo)
Reasons why the coelem in so imporant.
Clue: SGCESS - support/gut/circ+excret/space/size
- fluid prov internal support
- seperate internal processes from gut
- allows tranp of fluids around circ + excret systems
- space for devt of internal organs
- enables inc body size
Describe the process of exocytosis
process in which vesicles fuse w cell membrane to release contents outside the cell
Why might single-celled organisms be limited in their capacity to excrete toxic waste?
no specialised organ → relies on passive forms of excretion = diff + osmo
What are the three broad measures of excretion in plants?
- transpiration
- storage
- diffusion
Why might water pressure (root pressure) build up at night?
stoma close → dec water uptake by plants in region → water remains in soil → pressure inc
Why is N one of the common waste products excreted?
all heterotrophic animals req protein → bc protein prod high conc of N when metabolised → lots of N needs to be excreted
Excretory products that are composed of N.
ammonia, urea, uric acid, guanine
Why is removing dung from your surroundings advantageous for an animal?
some predators + parasites able to locate prey/hosts thru smell of dung
→ leaf rolling catapillar has adaptation = anal plate → fires faeces out of leaf + far away when triggered by waste build-up
The honeydew produced by aphids is technically secreted rather than excreted. Why should we conclude this?
secretion is when the exuded substance serves a specific purpose. in this case honeydew is prov as a reward for ants bc deter predators = specific function.
contrast - excretion = removal of definitive waste products
Compare passive vs active movement
passive= relies on abiotic systems e.g. air, water currents to move
vs active = req E (worK)
What are the advantages and disadvantages of active and passive movement?
passive
- advantages: minimal E expenditure
- disadvantages: X control over destination - new environ may be suptoptimal
active
- advantages: can ensure move to optimal environ for own devt
- disadvantages: costs E - must balance w E needed for cell maintainance/reprod
What are the challenges of living on land?
- need bio structures to capture O in air
- dehydration/dessication bc lack of water
- UV radiation
- X support
- energy intensive bc maj mvmt = active
- terr ecosystems = complex + vary dramatically
Why might some species adapt to living both on land and in the water?
moving in the air = extremely E intensive bc fighting gravity + wind currents → t/f option to switch to water = saves E needed for cellular maintainance/reprod
Name three groups that use cilia for locomotion (at some stage in their lives).
slugs, snails, worms
Name two functions of flagella
- locomotion along a single plane
- sensory organelle
Large slime mould are able to feed more effectively; why might this be?
larger SA → more # cilia → able to move more quickly
How do Cnidarians and molluscs move?
via propulsion
What features do all chordates share?
- notochord
- dorsal nerve chord
- myomeres (segmented muscles)
Name two differences between cartilaginous and bony fish.
- buoyancy mechanism - cart fish have lg liver filled w low-density oil vs bony fish have swim bladder
- support mechanism - cart fish have pectoral fins that prov dynamicm lift vs bony fish have rays or lobes that support weight
Why is it unlikely that you would find an amphibian in the desert?
all amphibians req water to reprod
Wing structure of insects
??
Wing structure of birds
??
What is a monophyletic group?
refers to a group of organisms uniquely descended from a ancenstor/ancentral group
Why are archosaurs polyphyletic?
bc both birds + reptiles (multi phyla) evolved from common ancestor
Key differences in stance between reptiles and mammals?
- reptiles = sprawling (pressure on knee joint) vs mammals = erect (pressure on hip joint bc femur tucked under pelvis)
- reptiles → slither side-to-side vs mammals → move back 1/2 body forward/back i.e. same mvmt but diff plane of motion
Why is the ability to evolve longer legs an advantage?
quicker locomotion
Why is tool use so important?
better able to manipulate environ + hunt prey
Define fossil
any remains or trace of a once-living organism
Compare relative vs absolute dating
rel dating = stratigraphy (rock layer order) + index fossils (inferring fossils found together = from same time period)
abolsute = measure carbon content to chemically pinpoint time of origin
What info can fossil records reveal?
- dates
- physiology
- diet
- reprod mode
- mvmt
- mig
- devt
- thermoreg
- colour
- behaviour
What is origination rate?
rate at which new spp emerge
What is extinction rate?
rate at which spp go extinct
What is adaptive radiation?
rapid diversification of evol lineage to suit variety of lifestyles/eco niches
Why does adaptive radiation occur?
new environ niche AND/OR absence of comp
Where does adaptive radiation commonly occur?
lake + island ecosystems
What is mass extinction?
sig divergence from regular extinction rates that causes rapid loss of diversity
Why does mass extinction occur?
CC, habitat loss, comp, predation
Varieties of mass extinction
local/global
taxonomically specific/broad
varying timescales
Why are we interested in understanding origination and mass extinction rates?
r/ship bw orig + ME rate determines if species is diversifying + ID adaptive radiations + mass extinctions
What is the Anthropocene?
period of time where humans are primary influ on environ
How did humans drive the dodo or Tasmanian tiger to extinction?
dodo → hunting + introduction of pred species (rats ate eggs)
TAS tiger → hunting, habitat loss, new diseases
What is the evidence that we are heading for a sixth mass extinction?
ext rates higher than background ext rates - Ceballos et al. 2015
extinction rates approaching level of ‘big five’ ME events- Barnosky et al. 2011
Human actions that cause extinction
- habitat loss
- species intro
- pollution
- overexploitation
- CC
ext of sml # species ⇒ cascading ext bc destab ecosystem
Habitat loss case study - Hawai’i
??
Cascading effects case study - coral
more C in atm → oceans acidifying bc carbonic acid (ocean PH dec from 8.21 to 8.10 since IR) → impacts calcifying marine life e.g. coral reefs - calcification (% weight inc per month) in 3 coral species dec as pH dec (Anthony et al. 2008)
What organisms are photoautotrophs?
green plants/some bacteria/algae
Details of anoxic photoautotrophs
- use H2S/org mols = electron source
- have bacteriachorophylls X chloroplasts
- live in harsh environs e.g. hot springs → imp for nutrient recycling
Details of oxygenic photoautotrophs
- photosynthesise → prod O biproduct
- e.g. cyanobacteria + algae
List animals that reproduce via internal and external fertilisation and describe the behaviours and adaptations that maximise the probability of gametes meeting
external - fish, frogs, coral, echinoderms → synch spawning + close prox
internal - humans
What are the benefits of internal fertilisation
- protects offspring from pred
- protects embryo from dehyd
How do insects respirate?
O2 diff thru trachea
Reptiles are…
holodonts
Label an insect’s mouthpart
Image 7
mx → manipulate
md → bite, cut
lb → store
lr → hold
Why are desert species unlikely to excrete ammonia?
need to conserve water but ammonia req lots water
Mammals’ shift in stance is…
faster/more energetically efficient
