microbiology final (chapter 6a)

The ideal pH for most fungi is:

5-6

Bacteria grow best at a pH of:

6.5-7.5

Which line represents a facultative anaerobe in an aerobic environment?

a

Which tube shows the growth pattern of an obligate aerobe?

a

As bacteria grow, the media that they are growing on will become:

acidic

Some foods such as sour kraut and pickles are naturally preserved because the pH is:

acidic

Bacteria that are tolerant of acidic environments are called:

acidophiles

Organisms that do not use atmospheric oxygen (O2) but are not harmed by it are

aerotolerant anaerobes

Which of the following are true? *about 70% of human infection involve biofilms *all of these are true *almost any device implanted in the body (Including contact lenses on the surface of the eye) make an ideal environment for biofilms *bacteria in biofilms are about 1,000X more resistant to antimicrobial compounds than individual bacteria

all of these are true

An increase in cell number along with an increase in cell size are both significant contributors to growth in:

animals and plants

Some archaea live in nature at temperatures of 121 degrees Celsius. Considering that the boiling point of water is 100 degrees Celsius. Where would you find liquid water in nature at 121 degrees Celsius?

around volcanic vents on the bottom of the ocean

Which line represents a facultative anaerobe in an anaerobic environment?

b

Which tube shows the growth pattern of a facultative anaerobe?

b

Which line represents an obligate aerobe in an anaerobic environment?

c

Which line represents an obligate anaerobe in an aerobic environment?

c

Which tube shows the growth pattern of an obligate anaerobe? (Hint: There is more oxygen at the top of the media than at the bottom.)

c

Hydrogen peroxide (H2O2) is broken down by:

catalase and peroxidase

Which tube shows the growth pattern of aerotolerant bacteria? (Hint: There is more oxygen at the top of the media than at the bottom.)

d

One of the common rules of food handling is to keep food cold or hot but not in between. You cooked a large batch of rice which you are going to use tomorrow in a class teaching people how to make sushi rolls. Assuming you don't want your students to get food poisoning, you should:

divide the rice into small batches and refrigerate it

Which tube shows the growth pattern of a microaerophile?

e

An organism that can carry out aerobic respiration when oxygen is available and then functions by means of fermentation or anaerobic respiration in the absence of oxygen are called

facultative anaerobes

Bacteria that do not require high salt levels but can tolerate it are called:

facultative halophiles

Which group of microorganisms is most likely to spoil a freshwater trout preserved with salt?

facultative halophiles

If you have bacteria growing on some left overs in your kitchen, those left overs would be a culture media.

false

Thermophiles can survive the temperatures used in food processing therefore they are a major concern in commercial food processing.

false

The archaea that live in hot springs in Yellowstone National Park are:

hyperthermophiles

Foods with high salt such as salt cured ham or high sugar such as sugar cured ham, jelly, honey or molasses, are ___________ solutions and bacteria that land on the food will___________.

hypertonic; die due to water loss by means plasmolysis

In nature, bacteria usually live

in groups inside a gel called a biofilm

When you add microorganisms to a culture medium, you are __________ the medium.

inoculating

Most human pathogens fall into which of these categories?

mesophiles

Bacteria that require oxygen but require it in lower concentrations than those found in the atmosphere are

microaerophiles

Which of these are physical requirements for growth?

none of these are physical requirements for growth

Organisms that require oxygen to live are

obligate aerobes

An organism that is unable to use atmospheric oxygen (O2) and can be harmed by it is called a(n)

obligate anaerobes

Biofilms are usually __________ shaped and about ___________ thick.

pillar; 10 micrometers

As bacteria begin to form biofilms, they produce a chemical attractant called an inducer which draws more bacteria. With more bacteria they produce more of the inducer wich draws still more bacteria. In A&P or some other class you probably studied negative feedback and positive feedback systems in the human body. This system in bacteria is similar a _______ feedback system in humans.

positive

Most of the nitrogen taken up by a bacterium is used to make:

protein

A few years ago, Blue Bell ice cream had to conduct a massive recall and shut down through production plant due to Listeria bacteria in the ice cream. Listeria can grow in ice cream. Listeria falls into which of these categories?

psychrophiles

When food spoils in the refrigerator, is most likely due to:

pyschotrophs

Even though bacteria are single celled organisms, once enough bacteria are collected together in a biofilm, they can have characteristics similar to a multicellular organism such as cell to cell communication and coordination of activities. This is called

quorum sensing

Organisms that tolerate atmospheric oxygen, O2, must have the enzyme ____________ which converts the more toxic forms of oxygen to _________________.

superoxide dismutase (SOD); hydrogen peroxide (H2O2) and atmospheric oxygen (O2)

Nitrogen fixation is

the conversion of gaseous N2 into N contained in an organic molecule

Bacteria that lack superoxide dismutase SOD cannot tolerate atmospheric oxygen.

true

Chemoheterotrophs get their carbon and energy from the same organic molecules.

true

Humans use highly reactive and toxic forms of oxygen to kill pathogens ingested by phagocytic white blood cells.

true

Most of the trace elements, such as iron, copper and zinc, serve as cofactors in bacterial cells.

true

Organisms that can tolerate atmospheric oxygen (O2) produce hydrogen peroxide (H2O2) which is toxic to the organism.

true

Oxygen can be destructive to organic molecules.

true

Some forms of oxygen are more reactive than O2 and are more destructive to organic molecules than O2.

true

Which of the following is an organic growth factor?

vitamin B1