1 - Food is An Ecosystem

Question 1

Phototrophs eat ____________ and make ____________

Answer 1

eat sunlight / CO2, make O2

Question 2

Anaerobic Methanogens eat ____________

Answer 2

CO2

Question 3

Anaerobic Methanogens make

Answer 3

CH4

Question 4

Aerobic Methanotrophs eat ____________

Answer 4

CH4

Question 5

Aerobic Methanotrophs make ______________

Answer 5

CO2

Question 6

Ecosystem is ___________________

Answer 6

a series of interactions between the environment and the organisms that inhabit it

Question 7

Food ecosystems, like all ecosystems, are impacted by the generation and utilization of ___________

Answer 7

energy

Question 8

TRUE OR FALSE: The human (and animal) gastrointestinal tracks are also ecosystems

Answer 8

TRUE

Question 9

Food ecosystems (especially when they include human pathogens) affect _______________, and may result in illness

Answer 9

host-ecosystems

Question 10

Food ecosystems are composed of _______ and ________ factors

Answer 10

intrinsic and extrinsic

Question 11

Intrinsic factors are factors inherent to the food including:

Answer 11

pH, water activity, nutrients

Question 12

Extrinsic factors are factors external to the food

Answer 12

Temperature, gaseous atmosphere

Question 13

TRUE OR FALSE: Intrinsic and extrinsic factors may change over time as bacteria grow and produce bi-products

Answer 13

TRUE

Question 14

Food can be heterogenous on a micrometer scale and may contain several ________ (aerobic vs anaerobic)

Answer 14

microenvironments

Question 15

Describe in detail the bacterial growth curve :

Answer 15

y-axis: number of bacterial cells
x-axis: time
lag phase, log or exponential growth phase, stationary phase and death phase

Question 16

Bacteria must have ________ for building the array of chemical substances of which they are composed (anabolism)

Answer 16

carbon

Question 17

Autotrophic (cyanobacteria) bacteria obtain their carbon source from

Answer 17

CO2 through carbon fixation

Question 18

Heterotrophic (Listeria monocytogenes) bacteria obtain their carbon source from

Answer 18

organic compounds

Question 19

Mixotrophic bacteria obtain their carbon source from

Answer 19

combining auto and heterotrophy

Question 20

Bacteria must have a source of ________ for living (catabolism)

Answer 20

energy

Question 21

Chemotrophic bacteria obtain their energy from:

Answer 21

external chemical compounds

Question 22

Phototrophic bacteria obtain their energy from:

Answer 22

light

Question 23

Bacteria must have a source of ______ to be used in energy conservation and biosynthetic reactions

Answer 23

electrons

Question 24

Lithotrophic bacteria obtain their reducing equivalents from:

Answer 24

inorganic compounds

Question 25

Organotrophic bacteria obtain their reducing equivalents from

Answer 25

organic compounds

Question 26

Bacteria must have an electron _________

Answer 26

acceptor

Question 27

Aerobic organisms use _______ as a terminal electron acceptor (this is the most energetically favourable reaction)

Answer 27

oxygen

Question 28

Fermentation uses _________ as a terminal electron acceptor, therefore, fermentative organisms are considered _________

Answer 28

organic carbon, anaerobes

Question 29

If an organism can grow with or without oxygen they are called __________

Answer 29

facultative anaerobes

Question 30

succinate fermentation or oxalate fermentation are examples of ______

Answer 30

very low energy yielding fermentation reactions

Question 31

Catabolism = energy ________

Answer 31

generation

Question 32

Anabolism = energy ________

Answer 32

consumption

Question 33

Lactic acid bacteria produce relatively large quantities of ___________

Answer 33

lactic acid from carbohydrates (ex: lactobacillus in yogurt)

Question 34

Proteolytic bacteria hydrolyze _______ because they produce _________________ (Clostridium botulinum)

Answer 34

proteins, extracellular proteinases

Question 35

Lipolytic bacteria hydrolyze ________. because they produce _____________

Answer 35

triglycerides, extracellular lipases

Question 36

Thermophilic bacteria:

Answer 36

bacteria that are able to grow at 50C and above

Question 37

Thermoduric bacteria

Answer 37

able to survive pasteurization temperatures

Question 38

Psychrotrophic bacteria

Answer 38

able to grow at refrigerated temperatures (below or equal to 5C)

Question 39

Cryophilic bacteria

Answer 39

able to grow at freezer temperatures (below or equal to 0C)

Question 40

Halophilic bacteria

Answer 40

able to survive high salt concentrations (equal or above to 10%)

Question 41

Aciduric bacteria

Answer 41

able to survive low pH

Question 42

Osmophilic bacteria

Answer 42

able to grow at a higher osmotic environment

Question 43

Spore formers:

Answer 43

able to produce spores (C.botulinum)

Question 44

Coliforms:

Answer 44

used as an index for sanitation

Question 45

Fecal coliforms:

Answer 45

used as an index for sanitation, presence indicates fecal contamination

Question 46

Enteric pathogens:

Answer 46

can cause gastrointestinal infection

Question 47

Relative abundance of a specific type of microorganism will depend on _______ and ________

Answer 47

intrinsic and extrinsic factors

Question 48

Why is milk a good environment for microbial growth?

Answer 48

- high carbohydrates (lactose) - high protein - both great sources of carbon and energy for microbial growth

Question 49

Several microbes in fish are _______

Answer 49

halophiles

Question 50

Fish harvested from water polluted with human waste can contain several varied pathogens like _________

Answer 50

Vibrio cholerae

Question 51

Microorganisms can grow rapidly in fish because of ___________________________

Answer 51

high water availability, the pH of the tissue, and the availability of carbon and nitrogen

Question 52

What are the sources of contamination for fruits and vegetables:

Answer 52

soil, water, air, animals, insects, birds, equipment, harvesters,etc

Question 53

In canned foods, if pH is lower than 4.6 pathogenic mesophiles ___________

Answer 53

cannot germinate and produce illness causing toxins (C.botulinum)

Question 54

If pH is above 4.6 pathogenic mesophiles are not an issue, but if cans are temperature abused (stored over 40C) :

Answer 54

thermophilic spores can germinate and cause spoilage

Question 55

T or F: Staphylococcus cannot grow in canned foods, however, it’s toxins can survive the canning process

Answer 55

T