fungi Flashcards
features of fungi
-they do not make their own food
-they are mostly multicellular
-they are made up of threads called hyphae
-hyphae combine in masses to form mycelium
-their walls are made of a carbohydrate called chitin
how do fungi take in food
they are heterotrophs so they take in food made by other organisms
name the two types of fungi
parasitic
saprophytic
saprophytic fungi
-most fungi are saprophytic
-they obtain nutrients from dead material
-as they digest it minerals are released and recycled
-they play a vital role in the environment as they are responsible for decay
name some saprophytic fungi
mushrooms
moulds
parasitic fungi
-absorb their food from live hosts
-they get their food mostly from plants
-some live on animals eg athletes foot
two kinds of parasitic fungi
obligate parasites
-live on host but do not normally kill them
facultative parasites
-kill the host and feed on the remains
example of a symbiotic relationship of fungi and another organism
lichen
combination of a fungus and an algae
what does rhizopus consist of
-threadlike structures called hyphae
-are tubular with no crosswalls
-are multinucleate, each nucleus is a haploid
what are large numbers of hyphae called
mycelium
role of hyphae
digest the substrate on which they grow
function of rhizoids
provide extra surface area for absorption of the digested material
what are stolons
arial hyphae which allow rhizopus to spread sideways
nutrition of rhizopus
-rhizopus secrete enzymes out onto starchy food
-digestion takes place outside the fungus
-the digested nutrients are absorbed
-rhizoids give a large surface area for this to happen
what is asexual reproduction in a rhizopus called
sporulation
how does sporulation work
- sporangiophores grow up from the substrate after a number of days
- cells within the sporangium divide by mitosis to produce spores (haploid)
- the sporangium dries out in the right conditions and opens releasing many spores
- each spore will grow into a new hypha and mycelium if it lands on a suitable substrate
what is sporulation
the process of making spores
when does sexual reproduction in rhizopus happen
-under adverse conditions like extreme temperatures
-can only happen between a plus and a minus strain
how does sexual reproduction in rhizopus work
- when hyphae from opposite strains grow close together swellings grow on both strains and touch each other
- nuclei from both hyphae move into these swellings which are now called progametangia
- cross walls form to produce gametangia
- the walls of the gametangia dissolve and a number of fertilisations take place producing diploid zygote nuclei
- a zygospore forms around these nuclei
- when conditions are suitable the zygospore germinates by meiosis
- a hypha grows out of the zygospore and produces a sporangium at the tip
- the sporangium opens releasing many haploid spores which grow into new individuals
what is asexual reproduction in yeast called
budding
explain the process of budding
- the nucleus of the parent cell divides by mitosis
- one of the daughter nuclei enters a small developing bud on the outside of the yeast cell
3.usually the bud separates from the parent to become an individual cell, however sometimes this does not happen and the daughter cell itself buds, in this way long colonies of yeast cells can develop
benefits of fungi
-yeasts can be used to make bread and alcohol such as wine and beer
-can be used as a source of food eg mushrooms
harmful effects of fungi
-can attack crops eg corn and wheat, causes major financial losses as a result
-athletes foot and ringworm can affect animals
-can spoil food eg rhizopus grows on bread