ch 40, 39, + ecology Flashcards
4 main stages of food processing
- ingestion
- digestion
- absorption
- elimination
can animals use macromolecs in their polymer state?
no; must be broken down into monomers first
digestion
the process of breaking down food into molecs small enough to be absorbed
monomers
fuel for ATP prod or for biosynth
what does mechanical fragmentation do?
incs SA for digestive enzymes
food vacoules
organelles in which hydrolytic enzymes break down food (intracellular digestion)
what is one advantage of having extracellular digestion?
much larger food than by phagocytosis
what groups do not have complete digestive tracts (2)?
cnidaria, platy’s
complete digestive tract (3)
- mouth
- digestive tube
- anus
crop/stomach
storage & preliminary digestion
gizzard
grinding
intestine
absorption of nutrients into blood
what does a complete digestive tract enable?
ingestion of additional food before earlier meals are completely digested
peristalsis
rhythmic waves of contraction by smooth muscles in gut wall push food along
sphincters
muscular ring-like valves that regulate passage of material btwn specialized chambers
4 accessory glands
- gall bladder
- liver
- pancreas
- salivary glands
what does saliva lubricate food with?
a glycoprotein (mucin) + salivary amylase
what does salivary amylase do?
hydrolyzes starch and glycogen into smaller polysaccharides
tongue
tastes, manipulates, shapes food into a bolus
pharynx opens to both
- esophagus
- trachea
epiglottis
a cartilaginous flap that blocks the glottis when swallowing
rugae
accordion-like folds in the stomach that stretch to accommodate food
what does the stomach secrete and for what?
gastric juices to churn
what is the pH of the gastric juices in your stomach
2
what do the gastric juices do (2)?
- denatures pros
- kills most bacteria that are swallowed
pepsin
begins hydrolysis of pro’s by breaking peptide bonds
why is pepsin secreted in an inactive form, pepsinogen?
HCl activates it; don’t want it all the time
how many days does it take the epithelial cells in our stomach lining to be completely replaced by mitosis?
3 days
mixing and enzyme action converts food into nutrient rich..?
acid chyme
acid reflux/heartburn
occasional backflow into lower esophagus
pyloric sphincter
regulates the opening to the small intestine
how long, on avg, does it take for the stomach to empty?
2 hrs
small intestine (2)
- digests
- absorbs nutrients into blood
how long is the small intestine in humans?
6m
what does the small intestine perform?
enzymatic hydrolysis
duodenum
first 25cm of the small intestine
acid chime mixes with digestive juices from (4)
- pancreas
- lives
- gall bladder
- intestinal epithelium
pancreas prods (2)
- hydrolytic enzymes
- alkaline solution rich in bicarbonate, which red. the acidity
what produces bile?
the liver
where is bile stores until it is needed
gall bladder
bile salts in liver aid in the digestion of?
fats
what do pancreatic amylases do?
hydrolyze polysaccs into disaccs
what does maltase do?
splits maltose into 2 glucose molecs
sucrase splits sucrose into
glucose and fructose
what two molecs secreted in inactive form by the pancreas attack specific peptide bonds?
trypsin and chymotrypsin
how are fats dealt with (2)?
- bile salts coat droplets and keep them emulsified
2. lipase hydrolyses fat molecs into glycerol and fatty acids
where does most digestion occur?
duodenum
what two structures absorb nutrients with their huge SA?
jejunum and ileum
villi
fingerlike protections for absorption found on the intestinal lining with many microvilli on it
SA via (4) structures
- length
- plicae
- villi
- microvilli
what two cell layers separate lumen of intestine from the bloodstream?
intestinal epithelium and epithelium of capillaries
hepatic portal vessel (2)
where intestinal veins converge; leads to liver
regardless of carb content of meal, blood has glucose [] close to ?
0.1%
large intestine major function
reclaiming w
how long is the human colon?
1.5m
how much of the 7L of w secreted into the digestive tract every day is reabsorbed?
over 90%
colons have a rich flora of bacteria which (2)
- are mostly harmless
- prod vitamins
what is one of the major reasons mammals have been so successful?
teeth; specialized dentition
who has longer intestinal tract:body size ratio?
herbivores and omni
what is harder to digest, meat or plants?
plants; cellulose
how do we break down cellulose?
w/ symbiotic bacteria in special fermentation chambers that have enzymes that can digest cellulose and simple sugars
homeostasis
steady state physiological condition of body
-ive feedback
a change in the variable being monitored triggers a response that counteracts initial fluctuation
what is the primary mechanism of homeostasis?
-ive feedback
when blood glucose levels rise above a certain point (2)
- pancreas secretes insulin into blood
2. insulin stimulates liver and muscle cells to make glycogen, dropping blood glucose lvls
when blood glucose levels drop below a certain point (2)
- pancreas secretes glycagon into blood
2. glycagon promotes breakdown of glycogen and release of glucose into blood
what is the endocrine function of the pancreas?
signals cells to regulate lvls in the blood
what is the exocrine function of the pancreas?
secretes digestive enzymes in ducts
+ive feedback
a change in some variable triggers mechanisms that amplify change
what is one example of +ive feedback that relates to cc?
albedo affect
who has an open circulatory system?
arthropods and mollusks
hemolymph
no distinction btwn blood and interstitial fluid
closed circ system
blood confined to vessels
closed circ system of vertebrates
cardiovascular system
atria
chambers that receive returning blood
ventricles
chambers that pump blood out
what happens to blood pres when blood flows through a capillary bed?
drops substantially
how many chambers does a fish heart have?
2
how many chambers do amphibians and reptiles hearts have?
3
one disadvantage of amphibian hearts
mixing of O2 poor and rich blood
what is one advantage to a 4 chambered heart?
restores pres and prevents blood mixing
what is one essential adaptation for endotherms?
a 4 chambered heart
how much more E do endotherms use over endotherms?
10x more
4 chambered hearts in birds and mammals is an example of
convergent evolution
ecology
the study of interactions btwn orgs and their env
env includes
biotic and abiotic factors
pop
a species
community
pops that interact w/ each other in a specific area
ecosystem/biome
community + abiotic factors
organismal ecology studies ?
how orgs meet the challenges of their envs, through morphology, physiology, and behaviour
pop ecology studies?
interactions w/in species; pop growth, size, structure
community ecology studies?
interspecies interactions; parasitism, disease, predation, competition
ecosystem ecology studies?
how E and nutrients flow through a ecosystem
how to nutrients flow?
recycled
E in a system
passed upwards but some is lost in every transformation
what determined where a species is or isn’t found (4)
- ability to disperse
- behaviour
- biotic factors (predators, parasites, competitors, etc.)
- abiotic factors (geology, sunlight, climate)
3 ways of sampling the density of a pop
- sample plots (quadrats)
- indirect indicators (nests, droppings, etc.)
- mark & recapture
3 ways of describing pops
- density
- dispersion
- demography
3 types of dispersion
- clumping
- uniform
- random
why would orgs clump (2)?
- food, nesting sites, etc
- social behaviours, mating
why would orgs be uniformly dispersed?
antagonistic interactions; territoriality, plant allelochemicals, etc
why would orgs be randomly dispersed?
no interactions (rare)
demography
the study of vital statistics that affect pop size
what are some vital statistics that affect pop size (2)?
- birth and immigration rates
- death and emigration rates
life tables
summarize the vital stats of a pop
what do life tables do (2)?
- follow a cohort from birth to death
- measure mortality, survivorship, births, etc through diff age classes
survivorship curves
plot a portion of cohort still alive vs age
type 1
small # of well-cared for offspring; many survive to old age
type 2
consistent line
type 3
offspring w/ no parental care; many die young
natural selection favours strategies that?
max lifetime repro success
fitness
how many offspring you have that survive to adulthood compared to others in the pop
good fitness is affected by (3)?
- clutch size
- # of repros/lifetime
- age at 1st repro
clutch
offspring/event
how does clutch size relate to offspring size (2)?
- smaller clutch, bigger offspring
- bigger clutch, smaller offspring
early breeding females are often smaller. what does this result in (3)?
- smaller clutch
- less E for later clutches
- lower lifetime repro success
exponential growth model
assumes max rate of growth (r max)
r max (3)
- max birth rate per female
- all kids survive
- repro forever & faster->
k
max # that env can support
logistic pop growth
pop limited by K (Carrying capacity) of the env
which model can life histories be related to?
logistic pop growth model
r-selected species (5)
- evolved to maximize r-max (inc quickly)
- favours opportunists
- many small offspring
- no parental care
- type 3 survivorship curves
k-selected species (5)
- evolved in pops that were near carrying capacity (high density)
- not opportunists
- few, big offspring
- parental care
- long life; delayed maturity
- type 1 survivorship curves
what regulates pop size?
a combination of density dependent and independent factors
density dependent pop regulation
effects inc as pop size incs; tends to keep the pop around k
3 eg of effects that inc as pop incs
- less resources per individual
- predation incs
- crowding changes behaviour/physiology
what does less resources/individual mean for a pop (2)?
- less food, territories, nest sites
- lower survival, less offspring
what does crowding mean for a pop?
delayed maturity, fewer offspring
density independent factors
abiotic factors that decrease a pops size no matter how big/small; natural disaster, weather
fluctuations
- r-selected spp sometimes have big fluctuations
- k has some
cycles (2)
- 10 or 12 yr turns
- regular cycles may be due to time lags of density-dependent factors (predation, epidemics)
what model do human pops follow?
exponential
5 reasons humans follow the exponential model
- clean w
- sanitation
- medicine
- agri
- technology/mechanization
what are 4 ways medicine helps humans achieve the exponential growth model?
- stop of infectious disease
- antibiotics
- hygene
- immunization
rate of growth of human pop influenced by (2)
- what country you’re in
- age structure (lots of kids inc pop later)
how many kids/woman would keep the pop even?
2.1
carrying cap for humans?
10-15 bill
ecological footprint
land and w area needed by a nation/person to get all of its resources and dispose of its wastes
why does ecological footprint vary with country?
because resources are limited; not evenly distributed
what is the human pop doing to the carrying capacity for other spp?
dec
interspecific
existing or occurring between different species
intraspecific
produced, occurring, or existing within a species or between individuals of a single species
interspecific interactions include (7)
- competition
- predation
- herbivory
- mutualism
- disease
- commensalism
- parasitism
ecological niche
the sum of a species’ use of the biotic and abiotic resources in its env; how and where it makes its living
competitive exclusion principle
no two species can occupy exactly the same niche
what happens if two species occupy the same niche (4)?
- the superior competitor may drive other spp to extinction
- competition may limit a sp to a more limited niche than it might otherwise occupy
- species w/ similar niches may come to subdivide the niche (resource partitioning)
- direct competition may push sympatric pops od species to become diff (character displacement)
predation drives
evolutionary “arms race”
predators evolved (4)
- speed
- good sensory systems
- camoflague
- mimicry
prey evolved (7)
- speed
- hiding behaviour
- cryptic colouration
- mechanical defenses
- group defenses
- group vigilance
- chem defenses
aposematic colouration
warning of defenses
Batesian mimicry
harmless sp resembles a dangerous one
Mullerian mimicry
several diff spp resemble each other
herbivory
plant/algae is partially consumed
plant adaptations (3)
- tough covering hairs
- gritiness
- 2ndary compounds (toxins, etc)
herbivore adaptations (2)
- ability to detect plant
- ability to overcome host defenses (detoxify, store to use them itself, etc)
parasitism
parasites harm the host
ectoparasites
found on outside of host
endoparasites
feed inside host
eg. salt march community
parasitism may play an important role in forming community structure
disease is mostly due to microscopic pathogens (4)
viruses, bacteria, fungi, protists
what are 2 species that are susceptible hosts to diseases?
- chesnut
- elm
mutualism
interactions that favour both spp
two egs of mutualism
- Acacia and speudomyrex ant
- pollinators and angiosperms
commensalism
one species benefits, one neither gains nor loses
co-evolution
one sp has put a selective pressure on the other and vice versa
one eg of commensalism
cattle and birds
species diversity
the variety of diff kinds of orgs in a comm
community characteristics (4)
- species diversity
- feeding relationships
- the role of 1 or 2 key species
- responses to disturbance
2 components of species diversity
- species richness
- relative abundance of each spp
why is it better to think in food webs rather than food chains?
many spp don’t occupy just one trophic level
E transfer btwn trophic lvls is usually what % efficient?
under 20% (limits food chain length)
what lvl of a food chain is the most precarious?
top
dominant spp
most abundant/have greatest biomass
what do dominant spp do?
influence which other spp can survive there
keystone spp
need to be abundant but act to maintain diversity (not always dom)
2 egs of keystone species
- seastars: eat mussels and stop them from dom
- sea otters: eat sea urchins that would otherwise destroy kelp forests
ecosystem engineers
cause physical changes that affect comm structure
3 egs of ecosystem engineers
- humans
- beavers
- termites
one eg of a comm that has evolved in the face of regular disturbances
lodgepole pine; fire
ecological succession
gradual predictable change in a comm structure after a disturbance
primary succession
begins from bare rock
secondary succession
begins from intact soil
eg of secondary succession
bare rock -> moss/fireweed -> shrubs -> alder forest -> spruce forest -> hemlock and spruce forest (climax)
why does succession occur (2)?
- each stage creates conditions that favour the next stage
- inhibit members of current stage (alders killing their own kinds)
why is there greater diversity in tropical habitats (2)?
- more E
- stability
island equil model (3)
- predicts that species # is related to ‘island’ size and distance to a ‘mainland’
- more spp = lower rate of arrival of new spp b/c most of those spp are already on the island
- more extinctions of new arrivals b/c more competitive exclusion
island equil model predicts
more species on large islands near the mainland
individualistic hypothesis
the plant spp in a place simply have similar ecological reqs
integrated hypothesis
comm is an association of ecologically linked spp
eg of integrated hyp
hemlock and western red cedar
