bio exam 3

green world hypothesis

top-down approach; predators, parasitism, and disease prevent herbivores from consuming all of the primary producers (plants)

species richness

the total number of different species

relative abundance

the proportion each species represents

shannon diversity index (H)

between 1.5-3.5; the larger, the more diversity; takes into account total number of species in a community=richness

biogeographic factors

location and size, equatorial-polar gradients (species richness and biodiversity peak near the equator)

dominant species

the most abundant

keystone species

the most influential

foundation species

one that allows other species to inhabit a given area by altering the environment

umbrella species

selected for conservation due to large geographic ranges; legally protecting them shields other species that use their habitat

indicator species

species whose presence or absence provides information about the health of the environment; monitoring them helps to identify problems

intermediate disturbance hypothesis

moderate disturbances can create opportunities for greater species diversity

primary succession

begins in an almost lifeless area where soil has been removed by volcanic eruptions, glaciers, floods, or landslides

secondary succession

begins in areas where a disturbance removes some or all of the organisms but leaves the soil intact; e.g, fires, logging

facilitation

early stages; promotes other species by improving area (lichens, moss)

tolerance

early arriving species do not hinder or promote the environment; usually r-selected. the tolerant, late-successional species outcompete early species

inhibition

early species prevent the establishment of later species; cycle usually ends due to outside disturbance (fire, storm)

ecosystem

a system of multiple communities along with their chemical and physical environments

energetic hypothesis

limited by the inefficient of energy transfer along the chain; 10% of energy transfer from one tropic level to the next

dynamic stability hypothesis

long food chains are less stable than short ones

gross primary production

the amount of light energy that is converted to chemical energy by photosynthesis per unit time

net primary production

gpp minus the energy used by the primary producers for cellular respiration (R); NPP = GPP - R

secondary production

the rate at which heterotrophs convert the chemical energy from the food they eat into new organic biomass and tissue

production efficiency

the fraction of energy stored in food that is not used for respiration; net secondary production/assimilation of primary production

assimilation

in energy transfer, assimilation represents the total energy taken in and consumed by the organism minus the energy lost in feces (e.g., 200 J of plant material eaten minus 100 J in feces leaves 100 J in assimilated energy)

net secondary production

the energy stored in consumer biomass that is actually available to subsequent trophic levels, after accounting for energy lost to cellular respiration (e.g., out of 100 J assimilated, 67 J goes to cellular respiration and 33 J becomes net secondary production)

light penetration

only 5-10% of the radiation may reach a depth of 20 m

eutrophication

influx of nitrogen or phosphorus containing fertilizers in freshwater lakes; mainly due to phosphorus pollution

evapotranspiration

amount of water transpired from plants and evaporated from the soil and other surfaces; increases with precipitation and solar energy

bottom-up

mineral nutrients, temperature, and light control plants dictate the abundance of the higher trophic levels

top-down

the upper trophic level has an impact on lower trophic levels

tropical rainforest decomposition

organic material decomposes in a few months to a few years; little accumulation as leaf litter on the forest floor

temperate forest decomposition

organic material decomposes in about four to six years

biome

a large, naturally occurring community of flora and fauna occupying a major habitat. biomes are primarily defined and classified by their climate, geography, and vegetation types

primary abiotic factors - terrestrial biomes

temperature and precipitation; global variations create distinct predictable climate patterns that shape which plants can grow where

primary abiotic factors - aquatic biomes

salinity, depth (sunlight penetration+pressure), and water flow

tropical rainforest

warm, high rainfall, highest global biodiversity, nutrient-poor because rapid decomposition causes plants to absorb nutrients almost immediately

subtropical desert

extremely low precipitation; extreme temperature fluctuations between day and night; plants have thick cuticles and spines to conserve water

arctic tundra

extremely cold, dark, and long winters with very low precipitation. there are low growing-mosses, lichens, scrubs, not trees. has permafrost (a layer of permanently frozen subsoil)

boreal forest (taiga)

very cold, long winters and short, wet summers. dominated by evergreen trees like pine, spruce, and fir. the soil is highly acidic and nutrient-poor

temperate deciduous forest

four distinct seasons with moderate, even precipitation. oak and maple trees. rich and nutrient-dense soil due to leaf decay

temperate grassland (prairie)

cold winters/hot summers; rich, highly fertile agricultural soils; dominated entirely by grasses due to periodic droughts and fires

savanna

tropical or subtropical; constantly warm but features a severe wet vs. dry season; grasses with widely scattered trees

chaparral

mild, rainy winters and hot, dry summers; drought-resistant evergreen shrubs and small trees; highly adapted to and depended on periodic wildfires for seed germination

freshwater

lakes/ponds (lentic/standing) and rivers/streams (lotic/moving)

marine

the open ocean, coral reefs, intertidal zones

photic zone

shallow, sunlit surface water where photosynthesis can occur; high oxygen levels

aphotic zone

deep, dark water where light cannot penetrate. dominated by heterotrophs and decomposers

benthic zone

the very bottom layer (sediment) where organic waste drops and decomposers recycle nutrients

headwaters

cold, clear, fast-moving, high in dissolved oxygen, but low in nutrients

downstream

warmer, murky (turbid), slower-moving, lower in oxygen, but highly rich in accumulated nutrients

estuary

transition zone between freshwater and saltwater ocean that features brackish water with fluctuating salinity levels; requires highly specialized adaptations from resident organisms

coral reefs

in warm, shallow, clear marine waters within the photic zone; require sunlight; symbiotic relationship with algae

prokaryotes

(bacteria/archaea) no membrane-bound nucleus, no membrane-bound organelles, DNA is a single circular chromosome in a nucleoid region, much smaller cell size.

unicellular eukaryotes

(protists/yeast) true membrane-bound nucleus, contain organelles, DNA is arranged in linear chromosomes

cocci

prokaryote shape: spherical/round

bacilli

prokaryote shape: rod-shaped

spirilla

prokaryote shape: spiral/helical

chemotaxis

prokaryotes moving toward nutrients or away from toxins

phototaxis

prokaryotes moving toward the light

extremophile

organisms that thrive in extreme environments; archaea

archaea

lack peptidoglycan in their cell walls, have unique membrane lipids, DNA replication similar to Eukarya rather than Bacteria, not a pathogen

phytoplankton

plant-like autotrophs; photosynthetic, autotrophic protists that drift near the water’s surface. they form the base of aquatic food webs and generate massive amount of global oxygen

zooplankton

heterotrophic, animal-like plankton (mostly unicellular protists or tiny larvae) that drift and feed on phytoplankton

cilia

short, hair-like projections that beat in coordination; often creates currents to sweep food into a cytostome (cell mouth) — paramecium

flagella

long, whip-like tails that propel the cell — euglena

pseudopodia

false feet; temporary cytoplasmic extensions used for crawling and engulfing good via phagocytosis — amoeba

hyphae

fungus; filamentous, thread-like structures that make up the body of a fungus

mycelium

fungus; an interwoven, underground mass of hyphae that maximizes surface area for nutrient absorption

fruiting body

fungus; the visible, above-ground macrostructure (like a mushroom) used strictly for reproductive spore dispersal

absorptive heterotrophy

fungi, through hyphae, secrete powerful exoenzymes into their surroundings to break down complex organic matter externally, then absorb the simple nutrients through their cell walls

mycorrhizae

mutualism between fungal hyphae and plant roots; fungus provides water/minerals, plants provides sugars

lichen

mutualism between a fungus and a photosynthetic partner (algae or cyanobacteria)

parasitic/pathogenic

fungus feeds off a living host, harming it (e.g., athlete’s foot, ringworm, or cordyceps insects)

porifera

sponges; asymmetric, no true tissues, use flagellated choanocytes to filter-feed

cnidaria

jellyfish, anemones, corals; radial symmetry, diploblastic, tentacles armed with stinging cells (cnidocytes)

platyhelminthes

flatworms; bilateral, triploblastic, acoelomate (completely solid body, no cavity), flattened body for gas exchange via disfusion

annelida

segmented worm (earthworms, leeches); distinct ring-like body segments

mollusca

snails, clams, octopuses; soft bodies often protected by a calcium carbonate shell; features a muscular foot, visceral mass, and a mantle

nematoda

roundworms; unsegmented, cylindrical bodies tapered at both ends; pseudocoelomate

arthropoda

insects, spiders, crabs; jointed appendages, segmented bodies, and a hard exoskeleton made of chitin (largest animal phylum)

echinodermata

sea stars, sea urchins; marine deuterostomes with pentaradial symmetry as adults and a unique water vascular system for movement

chordata characteristics

notochord, dorsal hollow nerve cord, pharyngeal slits or clefts, muscular post-anal tail

vertebrates

have a backbone/vertebral column that encloses and protects the dorsal nerve cord, alongside a distinct cranium protecting a well-developed brain

binomial nomenclature

consists of a Genus and specific epithet; must be italicized

hierarchal taxonomy

domain (eukarya) → kingdom (animalia) → phylum (chordata) → class (mammalia) → order (primates) → family (hominidae) → genus (homo) → species (homosapiens); Dear King Phillip Came Over For Good Soup

cladogenesis

a pattern of evolutionary change where a lineage splits into two or more distinct species (creates a branching node)

anagenesis

a pattern of directional change where an entire species accumulates changes over time and morphs into a new species without branching

ammonia

waste product; highly toxic; requires massive water to flush out. excreted by aquatic animals/bony fish

urea

waste product; moderately toxic; medium energy cost, saves water. excreted by mammals, adult amphibians, sharks

uric acid

waste product; least toxic; very high energy cost, precipitates as a paste to save maximal water. excreted by birds, reptiles, insects

amnion

encloses the fluid-filled cavity to cushion and protect the embryo from mechanical shock

allantois

disposes of metabolic waste (confronts toxicity) and assists in gas exchange

chorion

outermost layer; works with the allantois to handle overall gas exchange (O_2/CO_2)

yolk sac

encloses nutrients/yolk to feed the developing embryo

shared primitive character

trait shared with distant ancestor

shared derived character

shared by a group of organisms but not shared by a distant common ancestor