microbiology

Question 1

which micro-organisms fall under microflora

Answer 1

bacteria, archaea, fungi, algae, and viruses

Question 2

which micro-organisms fall under micro fauna

Answer 2

protozoa, nematodes, and small arthropods e.g. mites

Question 3

what are the two types of prokaryotes

Answer 3

bacteria and archaea

Question 4

what makes archaea different from bacteria

Answer 4

they show considerable morphological and physiological diversity e.g. more unusual shapes such as flattened square or triangular cells

Question 5

how many groups can bacterial cells be divided into

Answer 5

23 phyla

Question 6

what is the largest group of bacteria and what does it contain

Answer 6

proteobacteria - it is an extremely diverse group that contains a wide range of morphological forms.

Question 7

are all members of the Proteobacteria phyla gram positive or negative

Answer 7

gram negative

Question 8

what is a differential stain and give an example

Answer 8

a stain that does not stain all kinds of cells the same e.g. the gram stain

Question 9

what causes the difference in reaction to the gram stain and therefore the different results

Answer 9

The difference in reaction arises because of differences in the cell wall structure and composition of gram positive and gram negative cells

Question 10

what colour are gram positive bacteria after staining and which bacteria would fall under this grouping

Answer 10

purple - including genera such as bacillus, clostridium, lactobacillus, streptococcus and mycoplasma

Question 11

what colour are gram negative bacteria after staining and which bacteria would fall under this grouping

Answer 11

red - including E coli, Pseudomonas aeruginosa, Acetobacter species and Campylobacter jejuni

Question 12

name a few examples of the importance of fungi

Answer 12

fungi can be used in food production, like cheese manufacture and baking but also Quorn from mycoproteins. They are also used medicinally in the production of antibiotics

Question 13

what can fungal parasites of plants cause

Answer 13

crop diseases, billions of pounds worth of damage each year and periodic devastating disease epidemics

Question 14

what is the major problem with fungal pathogens of humans

Answer 14

although humans have a high degree of innate immunity to fungi, when infected there are only a few antifungal drugs available

Question 15

name 5 different diverse groupings of fungi

Answer 15

1. Moulds
2. Coprophilous fungi
3. Mushrooms and toadstools
4. Yeasts
5. Symbiotic associations

Question 16

what do Coprophilous fungi do

Answer 16

colonise sheep/ cow dung

Question 17

how do mushrooms/ toadstools relate to forensics

Answer 17

mushroom poisoning can be extremely toxic, however most people only suffer relatively mild and short-lived poisoning

Question 18

explain the symbiotic association of lichens

Answer 18

lichens is the association between a fungus and alga/ cyanobacterium - the alga provides the carbon compounds and the fungus provides physical protection, water and minerals

Question 19

explain the symbiotic associations of Mycorrhiza

Answer 19

a fungus will form little tiny root nodules of the roots of trees - the fungus will increase the root uptake of nutrients from nutrient-poor soil and in return gain sugars from the tree

Question 20

name 7 characteristics of fungi

Answer 20

1. Heterotrophic for carbon (cannot gain carbon from CO2)
2. Eukaryotic cell structure
3. Filamentous in most groups
4. Cell wall present
5. Grow via septation
6. Spores produced in reproduction
7. Non-motile (except in reproduction of some fungi)

Question 21

what is each filament of a fungi called

Answer 21

hypha

Question 22

what is a mycelium

Answer 22

a network of branched hyphae

Question 23

do fungi grow linearly or radially

Answer 23

radially

Question 24

what are fairy rings in regard to fungi

Answer 24

when fungi grow in a circle around a tree due to a connection between the fungi and the roots of the tree

Question 25

what do the cell walls of fungi contain

Answer 25

a mixture of fibrillar and amorphous/ matrix components

Question 26

what makes up the fibrillar component of the cell walls in fungi

Answer 26

chitin

Question 27

what is septation in fungi

Answer 27

the way they grow - they grow apically at intervals by transverse walls or septa into compartments - these septa will have perforations to allow for cytoplasmic flow

Question 28

what are the two reasons fungi produce spores

Answer 28

for dispersal and survival

Question 29

what are the two major types of fungi spores and define them

Answer 29

sexual - thick-walled and resistant to unfavourable environmental conditions asexual - produced in very large numbers for dispersal but normally have low resistance to unfavourable conditions

Question 30

what kind of spores does Mucor form

Answer 30

zygospores

Question 31

what kind of spores does Sordaria produce

Answer 31

ascospores

Question 32

what kind of spores does basdium produce

Answer 32

basidiospores

Question 33

what are the two types of asexual spores

Answer 33

Sporangiospores - spherical structure and non-motile Conidia - formed via a budding process

Question 34

what is the difference between higher and lower fungi

Answer 34

all higher fungi reproduce asexually via conidia spores whereas lower fungi reproduce asexually via sporangiospores

Question 35

what two things do all organisms require to grow

Answer 35

chemical elements for synthesis of cell constituents and energy-generating systems e.g. autographs or heterotrophs

Question 36

are fungi autographs or heterotrophs and what does this mean for them

Answer 36

autographs - gain energy from light or oxidation of inorganic compounds

Question 37

what is a heterotroph

Answer 37

an organism that gains energy found organic compounds

Question 38

what are the two major nutritional types of organisms and give examples

Answer 38

chemotrophs - animals, bacteria, fungi phototrophs - plants, algae and photosynthetic bacteria

Question 39

where do autotrophs get their carbons source from

Answer 39

CO2

Question 40

what are the 6 most important elements in nutritional requirements for organisms

Answer 40

1. carbon 2. hydrogen 3. oxygen 4. nitrogen 5. sulphur 6. phosphorus

Question 41

how does bacteria reproduce

Answer 41

via binary fission

Question 42

what is the doubling/ generation time in regards to binary fission

Answer 42

the time taken for one bacterium to become two

Question 43

what shape is a typical growth curve of population growth of bacteria in batch culture

Answer 43

sigmoidal

Question 44

what are the 4 phases of population growth on a typical growth curve

Answer 44

lag phase exponential/ logarithmic phase stationary phase death phase

Question 45

what are the 6 factors that can affect microbial growth

Answer 45

1. Nutrient availability 2. Temperature 3. pH 4. Aeration - oxygen and CO2 5. Moisture content 6. Presence of inhibitory substances

Question 46

which type of microbes prefer a temperature of <20 degrees in order for maximum growth

Answer 46

Psychrophiles

Question 47

which type of microbe requires an optimum temperature of 20-45 degrees for maximum growth

Answer 47

Mesophiles

Question 48

which type of microbe requires an optimum temperature of >45 degrees for maximum growth

Answer 48

Thermophiles

Question 49

are the majority of micro-organisms psychrophiles, mesophiles or thermophiles and why

Answer 49

Mesophiles - they break down organic matter in order to produce heat so that the temperature around them increases

Question 50

what is the optimum pH for most micro-organisms

Answer 50

7.0 as they are neutrophilic

Question 51

what is the optimum pH for most fungi

Answer 51

5.0 as they are more acid-tolerant

Question 52

what is an anaerobe

Answer 52

a micro-organism that does not require oxygen for growth

Question 53

what is an aerobe

Answer 53

a micro-organism that does require oxygen in order to grow

Question 54

what is a microaereophile

Answer 54

a micro-organism that will ONLY grow at low oxygen levels/ tensions

Question 55

why is the CO2 level also important for growth of micro-organisms

Answer 55

as they can cause small changes in pH as well as be inhibitory at high concentrations

Question 56

what is the relationship between microbial growth and moisture

Answer 56

directly proportional

Question 57

what is desiccation

Answer 57

too high of salt conditions for microbial growth

Question 58

what are the survival structures in place for both bacteria and fungi

Answer 58

both have spores (bacteria also may have cysts)

Question 59

why are endospores dangerous

Answer 59

as they are the most resistant forms of life known as they can withstand temperatures well above the boiling point of water and conditions of extreme desiccation. They can also remain visible in a metabolically inactive state for at least 300 years

Question 60

what makes endospores physically different to vegetative cells

Answer 60

they are smaller, highly refractile and also differ chemically by having a much lower water content

Question 61

name one example of a biological weapon related to micro-organisms

Answer 61

Anthrax

Question 62

what are bacterial cysts

Answer 62

a modified vegetative cell that can survive harsher conditions but not as harsh as endospores can