6.1

Question 1

define pathogens

Answer 1

micro-organisms that cause disease

Question 2

what is a culture

Answer 2

microorganisms are provided with the nutrients, level of oxygen, pH & temp that they require to grow large numbers so they can be observed & measured

Question 3

why do aseptic techniques need to be carried out when culturing

Answer 3

risk that the bacteria mutates & becomes pathogenic (even if it wasn’t to begin with)
risk of contaminating with pathogenic microorganism & growing it
could contaminate pure samplesd

Question 4

define sterile

Answer 4

something that is free from living microorganisms and their spores

Question 5

how do you dispose of culture

Answer 5

seal in plastic bag
sterilize at 121’C for 15mins under high pressure

Question 6

what is nutrient broth

Answer 6

a liquid nutrient for culturing microorganisms commonly used in flasks test tubes or bottles

Question 7

what is nutrient agar

Answer 7

a jelly extracted from seaweed used as a solid nutrient for culturing, used in petri dishes

Question 8

what is selective medium

Answer 8

a growth medium for microorganisms contaminating a very specific mixture of nutrients, so only a particular microorganism will grow on it

Question 9

what is inoculating

Answer 9

the process by which microorganisms are transferred into a culture medium under sterile conditions

Question 10

state 3 ways to grow a pure culture

Answer 10

grow under anaerobic/aerobic conditions

Question 11

what is a hemocytometer

Answer 11

a thick microscope slide with a rectangular indentation and etched grid of lines that is used to count cells

Question 12

what stain can be used to count only living cells

Answer 12

trypan blue
stains dead cells blue so only living cells can be counted

Question 13

what is a turbidimetry

Answer 13

a method of measuring the concentration of a substance by measuring the amount of light passing through it

Question 14

define turbid

Answer 14

something that is opaque or thick with suspended matter

Question 15

what is dilution plating

Answer 15

a method used to obtain a culture plate with a countable number of bacteria colonies

Question 16

what is a total viable cell count

Answer 16

a measure of the number of cells that are alive in a given volume of culture

Question 17

how can you measure the growth of fungi

Answer 17

measure the diameter of the patches of mycelium

Question 18

how can you measure the mass of cultured fungi

Answer 18

remove a sample from the separate the fungi & the liquid using a centrifuge or filtering
dry thoroughly at 100’C overnight then measure the mass

Question 19

what is the time between bacterial divisions called

Answer 19

generation time

Question 19

what limits the reproduction of bacteria

Answer 19

limited nutrients & space
build up of waste products

Question 19

what is lag phase

Answer 19

when bacteria are adapting to their new environment are not yet reproducing at their maximum rate

Question 20

what is log phase/exponential phase

Answer 20

when the rate of bacterial reproduction is close to or at its theoretical maximum, doubling in a given time period

Question 21

what is stationary phase

Answer 21

when the total growth rate is 0 as the number of new cells formed by binary fission is equal to the number of cells dying

Question 22

what is the death phase

Answer 22

when reproduction has almost ceased and the death rate of cells is increasing

Question 23

give an example of waste product of bacteria leading to their decline

Answer 23

CO2 produced in respiration builds up and lowers the pH to a point where bacteria can no longer grow

Question 24

define endotoxins

Answer 24

lipopolysaccharides that are an integral part of the outer layer of the cell wall of gram (-) bacteria

Question 25

what are the symptoms produced by bacterial endotoxins

Answer 25

fever, vomiting & diarrhoea

Question 26

how is salmonella spread

Answer 26

ingestion of food & water contaminated with infected feces

Question 27

state 3 ways to avoid salmonella

Answer 27

cook all meat thoroughly wash hands after handling raw meat & using the toilet avoid contaminated water

Question 28

what are exotoxins

Answer 28

soluble proteins that are produced and released into the body by bacteria as they metabolize and reproduce in the cells of their host

Question 29

which bacteria are exotoxins produced by

Answer 29

both gram (+) and gram (-) bacteria

Question 30

what are some of the effects of exotoxins

Answer 30

damage cell membranes -causing cell breakdown or internal bleeding act as a competitive inhibitor to neurotransmitters directly poison cells -fatal bacterial diseases

Question 31

give 3 facts about staphylococcus

Answer 31

only cause disease if they get inside tissues of the body gram (+) bacteria produce exotoxins that can cause mild skin diseases to rapid death

Question 32

state the third way that bacteria act as a pathogen

Answer 32

invade host tissues and damage cells

Question 33

what is tuberculosis

Answer 33

a lung disease caused by Mycobacterium tuberculosis & M.bovis

Question 34

how is TB spread

Answer 34

droplet infection; coughing, sneezing drinking infected milk working close to cattle

Question 35

what are the symptoms of tb

Answer 35

affects respiratory system damaging & destroying lung tissue suppresses the immune system coughing up blood

Question 36

what is primary infection

Answer 36

the initial stage of tb when it has been inhaled evaded the cells and multiplied slowly but often causes no symptoms

Question 37

what is a tubercule

Answer 37

the result of a healthy immune response to an infection, a localized inflammatory response forms a mass of tissue containing dead bacteria & macrophages

Question 38

what adaptation allows tb to survive primary infection

Answer 38

bacteria produce a thick waxy outer layer to protect them from enzymes of macrophages remain dormant in tubercules in the lungs until immune system has weakened

Question 39

define antibiotic

Answer 39

a drug that either destroys microorganisms or prevents them from growing & reproducing

Question 40

what does selective toxicity mean

Answer 40

that a substance is toxic against some types of cells and organisms but not others

Question 41

what is penicillin

Answer 41

the first antibiotic discovered it affects the formation of bacterial cell walls and it is bactericidal

Question 42

what's the difference between bacteriostatic & bactericidal antibiotics

Answer 42

bacteriostatic - inhibit growth of bacteria bactericidal - kill bacteria

Question 43

state 6 factors which antibiotic effectiveness depend upon

Answer 43

concentration of the drug in the area of the body infected how easily the drug can reach the tissue how quickly it is excreted local pH susceptibility of pathogen whether pathogen/host tissue can destroy the antibiotic

Question 44

what is antibiotic resistance

Answer 44

micro-organisms that are not affected by an antibiotic even if they have been effected in the past