Chapter 32 reading Flashcards
What is the reason for their being a lack of dead organic matter (d.o.m.) in tropical rainforest (and other ecosystems)?
fungi - they are responsible for decomposition of plant and animal tissues on land
What are features of fungi regarding consumption and access to energy?
depend on pre formed molecules for both carbon and energy
no organs, so absorb organic molecules directly thru cell walls
What are two major problems with no organs and reliance on pre formed carbon and energy for fungi?
more complicated molecules do no pass thru the cell wall
no means of locomotion
how do fungi deal with inability of larger molecules to pass thru cell wall?
fungi secrete enzymes that break down starch or cellulose
how do fungi deal with inability to move?
use process of growth to find nourishment - hyphae
What are hyphae?
highly branched, multicellular filaments, long & thin - provides large surface area for absorbing nutrients
What is mycelium?
the network of branching hyphae that forms the body of a fungus
Where are enzymes for breakdown of starch and cellulose secreted?
tip of the hyphae
What is the material of cell wall of hyphae?
chitin
What does chitin provide hyphae with?
a strong but flexible cell wall
What is chitin?
modified polysaccharide that contains nitrogen
What do hyphae and the mycelium formation allow for fungi to do?
grow between resource patches and produce reproductive structures like mushroom above ground
What do molecules that are absorbed by hyphae do? (chain reaction)
they drive osmosis which increases turgor pressure which increases growth and respiration in hyphae which decreases turgor pressure
= bulk flow
What does a continuous stream of cytoplasm in fungi do?
allows for movement of materials by bulk flow in mycelium
What are septa?
partitions between cell, has pores that allow transport of solutes along hypha
What is the function of septa?
when hyphae are damaged, sealing mechanism plugs pores preventing loss of pressurised cytoplasm
What is an example of a fungi that does not produce hyphae?
yeast
What is yeast?
single-celled fungi in moist, nutrient rich environments
Why don’t yeast have hyphae?
lost from descendants by convergent evolution
How do yeast divide?
by budding - a small outgrowth that increases in size and eventually breaks off to form a new cell
Where is yeast commonly found?
on surfaces of plants and sometimes on surfaces of animal gut
WHat are uses of yeast?
leavened bread, alcoholic bevs, in lab studies of genetics
What do fungi convert d.o.m. too?
CO2 and H2O
What do fungi do for carbon and life cycle?
keeps biological carbon cycle in balance and returns nutrients to the soil where they are able to support new plant growth
What are the advantages that fungi have to live on forest floor?
hyphae can expand fungi coverage > bacteria by flagellum
hyphae can break into interior of a food source (break down tree stems)
wood-rotting fungi produce enzymes that degrade lignin
How do fungal pathogens infect plants?
thru woods, stomata, or directly thru epidermal cells
What are fungal pathogens that cause agricultural losses?
ruts, smuts, and molds
What makes fungal pathogens good at invasion?
host specificity
What is an adaptation of invasion for Vascular wilt fungi?
hyphae through xylem vessels - makes it through entire plant
What species have vascular wilt fungi almost made extinct?
American Elm trees
How do aboveground plant infections usually spread?
via fungal spores - carried by wind or on insect bodies
How do belowground plant infections spread?
by hyphae that penetrate roots of plants
How can fungi exploit living-moving organisms?
by trapping them, sticky traps with hyphae, some lasso prey with rings that inflate and trap anything inside (like Nematodes)
What type of animals do fungi usually infect?
fish and amphibians (cold-body temp) so also bat species in winter hibernation
What is mycorrhizae?
symbiotic association with plants - provide roots with nutrients (P&N), get carbohydrates from host
What is ectomycorrhizae?
surround but do not penetrate root cells
What is endomycorrhizae?
hyphae penetrate into root cells and produce highly branched structures for large surface area for nutrient exchange (form a monophyletic group)
What are endophytes?
live within leaves - grow within cell walls and in spaces between cells - help improve plant growth during stressful conditions or produce chemicals that deter pathogenic invasion or herbivorous insect consumption
What is a lichen?
symbioses between a fungus and a photosynthetic microorganism (green alga or a cyanobacteria)
What is lichen make up?
bulk fungal hyphae
phtosoynthetic microorganism = layer underneath
What do hyphae do for lichen?
anchor to tree or rock
uptake and retention of water and nutrients to produce chemicals that protect organism against excess light and herbivorous animals
What does the green algae or cyanobacteria provide in lichen?
source of reduced carbon, cyanobacteria can fix nitrogen from atmosphere
How do lichens spread?
usually by fragmentation or thru formation of dispersal units consisting of single photosynthetic cell surrounded by hyphae
how are lichens adapted to be among the first colonizers of lava flows and barren lands post glacial retreat?
they can obtain nutrients from rainfall or secreting organic acids that release some nutrients from rocky substances
What are lichens tolerant to?
drying out, desiccation, fluctuations in temp and light
What are lichens sensitive to?
air pollution (SO2 esepcially) - so can be used as an indicator for industrial polllution
How do fungi reproduce?
asexual or sexual, through fungal spores
What increases fungi chances of reproducing?
large numbers of spores produced
What is sexual reproduction spore formation by?
meiotic cell division
What is asexual reproduction spore formation by?
mitotic cell division - produced by sporangia that form at ends of erect hyphae
What are fruiting bodies?
structures that release sexually produced spores into the air for dispersal (e.g. mushrooms, stinkhorns, puffballs, bracket fungi, truffles)
What allows for good dispersal for fungi?
elevation and forcible ejection
What are the 3/4 stages in the asexual cycle? are they haploid or diploid?
all haploid (n)
germination - mycelium formation - spore formation - dispersal …
What are the 8/9 stages in sexual cycle? are they haploid or diploid or else?
Germination (n) - mycelium formation (n) - Plasmogamy (formation of cytoplasm (n) - Heterokaryotic cell (unfused nuclei from different spores) (intermediate stage) - karyogamy (fusion of nuclei) ( intermediate to 2n) - zygote - meiosis (2n to n) - spores (n) - dispersal (n) - to start…
What is the heterokaryotic stage?
nuclei from two parental hyphae remains distinct and continues to divide eventually nuclei fuse and form a zygote
What is a dikaryote?
cells with 2 genetically distinct haploid nuclei
What are mating types?
fungi have different mating types that are genetically determined which prevent self-fertilization
What is parasexuality?
crossing over during mitosis is thought to provide genetic diversity in asexual fungi
