Exam 3 - Cont. Flashcards
are fungi heterotrophs? what makes them different
`yes but they are unique
they do not eat their food the same they acquire food through absorption
secrete enzymes that digest food extracellular and then absorb the resulting nutrients
is fungi more closely related to animals or plants
animals
where are fungi found
in soil and water
can fungi be parasitic
yes
they are essential decomposers in most ecosystems but some are also parasitic
parasitic fungi obtains their nutrients at the expense of plants or animals
what are typically fungi composed of
hyphae
cell wall
what is a fungi hyphae
threadlike filaments which branch repeatedly forming a feeding network known as mycelium
what is the hyphae surrounded by and what is it usually made of
surrounded by the cell wall
the cell wall is usually made of chitin
chitin is strong and flexible made of a nitrogen containing polysaccharide
what are cross walls
the hyphae of the fungi consists of chains of cells separated by cross walls
the cross walls contain pores large enough to permit the exchange of large organelles such as ribosomes mitochondria and nuclei to pass from cell to cell
do all fungi have cross walls
some fungi lack cross walls entirely
so they contain many nuclei within a single mass of cytoplasm
explain fungal mycelium growth
grows at a very rapid pace
branches through food sources and explores new territories
grow longer without corresponding increase in thickness
acts to increase the surface area for secretion of digestive enzymes and absorption
a mycelium can add as much as 1 kilometer of new hyphae each day
does fungi reproduce asexually or sexually
they c an reproduce in both ways
how are the fungal spores transported
a large number of haploid spores are released and are transported over large distances by either wind or water
if the spore lands in a moist environment with a food supply it will germinate producing new fungus
when does sexual reproduction of fungi result
when two haploid mycelia of different mating types release sexual signals growing toward one another and fusing
the cytoplasmic fusion is not immediately followed by fusion of the nuclei this stage is called a heterokaryotic stage
explain the heterokaryotic stage
when cells contain two genetically distinct haploid nuclei
hours days or even centuries may pass before the nuclei fuse giving rise to the generally short lived diploid phase
zygotes undergo meiosis within special reproductive structures producing haploid spores
what are some examples of fungi that can only reproduce asexually
molds and yeasts
called imperfect fungi
describe molds
refers to any rapidly growing fungus that reproduces asexually via spore production
spores are usually at the tips of specialized hyphae
found on rotting fruits and bread
describe yeasts
refers to any single celled fungus reproduce asexually via budding these inhibit moist habitats and liquids animal tissues plant sap
how many fungal species have been described
more then 100 000
maybe even 1.5 million
where did fungi diverge from and when
unikont ancestor more then 1 billion years ago
fossilized evidence exists from 460 million years
how are the fungal species typically classified by
sexual reproductive structures
all but one of the five groups of fungal lack flagellated spores
what are the 5 groups of fungi
chytrids zygomycetes glomeromycetes ascomycetes basidiomycetes
describe chytrids
the only group of fungi with flagellated spores
thought to represent the earliest lineage of fungi
found in lakes ponds and soil
some are decomposers others are parasitic to plants animals or protists
decline in some frog populations attributed to chytrid infection
describe zygomycetes
characterized by their resistant zygosporangium
diverse group that includes fast growing molds like black bread mold
molds that rot produce like strawberries
some are animals parasites
what is the zygosporangium
within this structure haploid spores form by meiosis
describe glomeromycetes
form distinct mycorrhizae
80% of plants have a symbiotic partnership with Add to dictionary
the glomeromycetes deliver phosphate and other minerals to plants while receiving organic nutrients in exchange
what are mycorrhizae
hyphae that invade roots branch into tiny treelike structures called arbuscules
describe ascomycetes
also called sac fungi
contain sac like structures called asci that produces spores via sexual reproduction
live in marine freshwater and terrestrial habitats
wide range in size
unicellular to large multicellular structures
some of the most devastating plant pathogens
other live in symbiosis with green algae and bacteria such as lichens
describe basidiomycetes
also called club fungi
most well know group of fungi and includes mushrooms
named for club shaped spore producing structure called basidium
many of these species are excellent at breaking down the lignin found in wood
therefore they play key roles as decomposers
include two groups of destructive plant parasites
1) rusts
2) smuts
how do zygomycetes reproduce
hyphae expand through food and the fungus reproduces asexually
produces spores in sporangia at the tips of hyphae
when food is depleted the fungus reproduces sexually
mycelia of different mating types join and produce a cell containing nuclei from both parents explain this
this young zygosporgangium develops into a thick walled structure able to tolerate dry or harsh environments
when conditions become favourable the two parent nuclei fuse and the diploid nucleus undergo meiosis
haploid spores are produced
how do ascomytes reproduce when conditions are favourable
asexually
when does sexual reproduction occur for many fungal species
the fall
the haploid spores mature in the spring
the genetic diversity of these new spores increases the likelihood that at least one genotype will survive and successfully establish itself in the new environment encountered in the new season
surviving individuals will reproduce asexually for many generations before once again reproducing sexually
explain the life cycle of a basidiomycete
a mushroom
heterokaryotic stage begins when two hyphae from two different mating types fuse
heterokaryotic mycelium is formed and grows producing the mushroom
in club shaped cells called basidia (the gills) haploid nuclei fuse forming diploid nuclei
each diploid nucleus undergoes meiosis producing haploid spores
mushrooms may release up to a billion spores
should the spores land on moist matter that may serve as a food source they will germinate and become haploid mycelia
how many fungi are parasitic
30% are parasites or pathogens
mainly plants
explain Dutch elm disease
accidentally introduced into the US from Europe on logs which were destined to become furniture
over a number of decades the fungus destroyed 70% of elm trees across the eastern US
what plant was completely wiped out by dutch elm disease
English elms
DNA analysis revealed that all of these trees were genetically identical
they were derived by asexual reproduction and therefore all equally susceptible
crops are usually genetically identical and thus highly susceptible to fungal disease
what causes 80% of plant disease what does this affect
caused by fungi
leads to huge economic losses
explain animal and fungal infections
animals are much less susceptible
range from minor like athletes foot to very serious like coccidiomycosis a fungal infection of the lung
yeast infections
define mycosis
a fungal infection
what is smut
a club fungus that infects corn
describe corn infected smut
grayish growth are called galls
galls are made of herterokaryotc hyphae which invade a developing corn kernel and eventually displace it
the mature gall will open releasing thousands of grayish black spores
define lichens
lichens are fungi living in close association with photosynthetic organisms
the association of millions of green algae or cyanobacteria wrapped tightly around a mass of fungal hyphae
such a close interaction that lichens are named as a single species
the fungus obtain food from the photosynthetic partner and the fungal mycelium provides a suitable habitat for the algae which helps the algae to absorb and retain water minerals
describe lichens
able to live in areas with little or no soil
important pioneers on new land
some tolerate severe cold and severe draught and can live in the arctic tundra
opportunists growing in spurts while conditions are favorable
describe lichens and climate
when it rains the lichens absorb water and photosynthesizes
in dry air the lichens dehydrates and photosynthesis stops indefinitely while the fungus remains alive
what does the death of lichens signify
lichens are very sensitive to air borne pollutants such as sulfer dioxide
the death of lichens is a sign of poor air quality
fungi receives most of its nutrients and minerals from the air
explain fungi and ants
have a mutually beneficial relationship
fungi are decomposers which produce enzymes that digest plant material such as cellulose
ants and termites take advantage of this and take the leaves to the host
the fungi feed on leaves using their enzymes
the ants eat the swollen fungal tips
queen ant takes fungal hyphae
some of these fungi are so dependent that they may no longer survive without ants
what are some importance of fungi
mushrooms
cheeses like blue cheese
yeasts used to produce alchohlic beverages and bread
important for antibiotic production (penicillium mold is responsible for penicillin)
define thermoregulation
the maintenance of body temperature within a tolerable range
define endotherms
warmed and heated by their own metabolism
what are some examples of endotherms
humans and birds
define ectotherms
gain most of their heat from the environment and other external sources
what are some examples of ectotherms
amphibians and fish
what is humans optimum body temperature
37 C
every animal has an optimal temperature range and its important to keep within this range
what are the four ways heat can be exchanged with the environment
- conduction
- convection
- radiation
- evaporation
define conduction
transfer of heat in between molecules by direct contact
heat always moves from the hotter object to the colder object
define convection
transfer of heat by the movement of fluid across a surface
define radiation
emission of electromagnetic waves
can transfer heat in between objects that are not in direct contact
define evaporation
loss of heat from the surface of a liquid
happens when a molecules obtains enough energy to leave the liquid and become gas
what are the 5 adaptations for thermoregulation
- metabolism
- insulation
- circulation
- evaporative cooling
- behavioral responses
explain metabolism
hormonal changes in cold weather boost the metabolic rate of mammals increasing heat production
additionally moving around more increases heat production
what is shivering
contraction of skeletal muscles
explain insulation
hair feathers or fat
raising or fur or feathers in response to cold traps heat against the surface of the body (goose bumps in humans)
explain circulation
heat loss can be controlled by changing the amount of blood flowing to the skin surface
blood vessels near the surface of the skin dilate and constrict
conserves heat in bodies trunk when necessary
explain evaporative cooling
panting sweating and spreading saliva on bodily surfaces all act to decrease body temperature
humans sweat
explain behavioural responses
migration of birds to different climates
basking in the sun when cold or seeking shade when hot
bathing functions to cool immediately
define excretion
the disposal of metabolic wastes
explain excretion
animals must dispose of nitrogenous wastes
nitrogenous wastes are products of protein metabolism
explain ammonia and excretion
ammonia is poisonous
water soluble and easily disposed of in animals
it is converted to urea which is less toxic and much safer within the body
urea and uric acid require energy to produce
explain asexual reproduction
results in offspring genetically identical to the parent
allows for the production of many offspring very quickly
what are the 4 types of asexual reproduction
binary fission
budding
parthenogenesis
regeneration
define binary fission
two equally sized cells are produced from one parent cell
define budding
two cells of unequal size are produced from one parent cell
define parthenogenesis
development of an unfertilized egg
define regeneration
entire body parts of some animals can be regenerated
in humans regeneration is limited to healing and tissue repair
liver has extensive regenerative capacity
define sexual reproduction
fusion of haploid gametes from two parents which forms a diploid zygote
results in extensive genetic variation within offspring
define hermaphroditism
both male and female reproductive organs are present on the same animals
in humans this can sometimes occur by mistake
describe external fertilization
occurs in many fish and amphibians
eggs and sperm are released into water for fertilization to take place
often physical contact is not required
timing is very important because the eggs must be ripe
describe internal fertilization
sperm are deposited within or close to the female reproductive tract and gametes unite within the tract
an adaptation that omits the need for water
requires copulation; sexual intercourse
what does the organization of an animals nervous system correlates with
the form of body symmetry
animals that are radially symmetrical have a nervous system that is
web liked
diffuses throughout the body
no central or peripheral nervous system
ex) nerve net in hydra
explain bilateral symmetry and the nervous system
these organisms tend to move through their environment
requires a head with concentrated sensory sensory organs
what are the two major adaptations of the bilateral symmetrical animals nervous system
cephalization
- concentration of the nervous system at the head end
centralization
- a central nervous system distinct from the peripheral nervous system
describe the vertebrae nervous system
highly specialized
CNS = brain and spinal cord
PNS = peripheral nerves
vertebrae and skull function to protect nerves
what are senses important for
animal function
guide movement
salmon use senses to find their breeding areas
bears use their senses to locate salmon
describe senses
sensory information arrives as a sensation to the brain
how the brain interprets this information is referred to as perception
collectively these senses gather information that facilitates feeding migrating and other behaviours
define sensory receptors
detect stimuli and convert the information into an action potential that is then sent to the brain
these receptors are highly specialized to pick up stimuli and are located within sensory organs
what are the sensory organs
eyes nose taste buds
the stimulus energy is transmitted into an action potential which is what will then be sent to the brain
what are the five categories of sensory receptors
pain receptors thermoreceptors mechanoreceptors chemoreceptors electromagnetic receptors
describe pain receptors
detect stimuli that are considered dangerous
describe thermoreceptors
detect heat or cold, monitors body temperature
describe mechanorecptors
respond to any changes in mechanical energy such as touch pressure and sound
define chemoreceptors
respond to chemicals
the nose and the mouth detect chemicals in the environment and those about to enter the body
internal receptors detect chemicals within the body
describe electromagnetic receptors
respond to electricity magnetism and light (detected by photoreceptors)
what are the three types of eyes that have developed in vertebrae’s
simple eye
many lens compound eyes of insects
single lens eyes of squid
describe simple eyes
these are cups that sense light intensity and direction
does not detect an image
describe many lens compound eyes of insects
each unit of the animal has a lens and picks up light from a small portion of the field of view
generates an image from that area only and all of the lenses together generate the entire picture which is pixelated
describe single lens eyes of squid
similar to a camera
single lens focuses the image using special muscles in the eye
describe the single lens vertebrae eye
cornea and the flexible lens focus the light via bending on the retina which contains photoreceptor cells
light passes through the lens which bends the light ray such that is falls on the retina
define near sighted and far sighted
near sighted- individuals are only able to see things that are close the object is focused within the eye and not on the retina
far sighted - individuals are only able to see things that are far away
the object is focused behind the retina
define locomotion
the active travel from one place to another
the animal must be able to overcome both gravity and friction
animals that swim are supported by the body of water but are also slowed by drag created in the water
animals that move on land are less opposed by friction but they must support their body weight against the force of gravity by
hopping
running
walking
crawling
what is the importance of skeletal support
skeletons provide support that is important for movement protection and support of organs and such
muscles pull against the skeleton during movement
protects internal organs within the cavity
define hydrostatic skeletons
fluid held under pressure in a body cavity
worms and cnidarians
describe exoskeletons
hard external cases
chitinous jointed exoskeletons of arthropods
includes shells of some molluscs
describe endoskeletons
hard or leathery supporting elements within the soft tissues of an animal
vertebrae endoskeleton is composed entirely of cartilage and bone
sharks have an endoskeleton composed entirely of cartilage
define a biological community
an assemblage of all populations of organisms living close enough together for potential interaction
what are some factors of a community
community boundaries are arbitrary
necessary for the conservation of endangered species and wildlife management
control of zoonosis and agricultural communities
can be described by its species composition
community dynamics and how species composition changes over time as a result of both biotic and abiotic factors
define inter-specific interactions within a community
members of one species may interact with members of a different species within a community
has a profound effect on population dynamics
define interspecific competition
populations of two different species competing for the same resource which is limited
has a negative effect on both populations
define mutualism
both species benefit from this interspecific competition
explain predation and inter specific interactions
an interaction in which one species kills a member of another species to be used as a food source
explain herbivory and inter specific interactions
the consumption of plants or algae by an animal
define an ecological niche
the sum of a species use of abiotic and biotic resources within an environment
when two populations have overlapping niches
both require a resource that is only present in limited supply
the effects of competition are easily studied by removing all members of a particular species from an area of interest
also function to lower the carrying capacity of an environment
explain mutualism
reef-building corals and photosynthetic dinoflagelletes
in order to build and sustain massive reefs that are a community staple lots of metabolic fuel is necessary
dinoflagellates gain a source of shelter an access to a light source and metabolic wastes of the coral
explain predation
huge impact on reproductive success
adaptations have developed In order to protect against predators
natural selection
