Chapter 9 Microbial Nutrition

Growth factors _______.

cannot be synthesized by the organism

The movement of molecules from an area of high concentration to an area of lower concentration is called ______.

simple diffusion

Facilitated diffusion and active transport require a carrier protein to mediate the movement across the plasma membrane.

true

The movement of substances from higher to lower concentration across a semipermeable membrane via a specific protein carrier but without energy expenditure is called ______.

facilitated diffusion

The phase of the bacterial growth curve in which newly inoculated cells are adjusting to their new environment, metabolizing but not growing at an exponential rate, is the ______.

lag phase

The term obligate refers to _______.

existing in a very narrow niche

Diffusion of water through a semipermeable membrane is called ______.

osmosis

Whether an organism is an autotroph or heterotroph depends on its source of nitrogen.

false

A bacterium is inoculated into a tube of thioglycollate and incubated. After incubation, turbidity appears throughout, top to bottom, with the greatest turbidty at the very top. This bacterium would be called a(n) ______.

facultative anaerobe

When microbes live independently (don't depend on each other for survival) but cooperate and share nutrients, it is called ______.

synergism

An organic nutrient that cannot be synthesized by the organism and must be provided is called a/an ______.

growth factor

A saprobe differs from a parasite in that _______.

a saprobe derive nutrients from dead plants and animals, but a parasite derives nutrients from living plants and animals

The production of antibiotics is a form of antagonism called ______.

antibiosis

A microorganism that does not have catalase or superoxide dismutase would find it difficult to live in an environment with ______.

oxygen

When whole cells or large molecules in solution are engulfed by a cell, this endocytosis is specifically termed ______.

phagocytosis

In regard to the tonicity, water is considered to be __________ environment, in which majority of bacteria would ___________.

hypotonic; burst (lyse)

Saprobes do not need a carbon source for growth and metabolism.

false

Staphylococcus aureus that is easily identified on MSA (mannitol salt agar), is a ________ species of bacteria that commonly cause cases of food poisoning due to the mishandling of food. Staphylococcus aureus tolerates slightly salty conditions because it can absorb salt (from the environment) to make its cell isotonic with the environment.

(HINT: a selective agent in MSA is 7.5% salt)

halotolerant

A halophile would grow best in ______.

salt lakes

Helicobacter pylori is a causative agent of Peptic Ulcers. H. pylori burrows into the gastric epithelium of its host because it doesn't tolerate acidic conditions in the stomach lumen nor requires high oxygen concentrations for its oxidative metabolic processes. Thereby, this bacteria is:

neutrophile; microaerophile

This food-born pathogen is psychrotrophic and can grow in meats and milk products during refrigerated storage. It primarily affects developing fetuses, newborns, older adults, and people with weakened immune systems, but rarely has harmful effects on immunocompetent people.

Listeria monocytogenes

Lithoautotrophs use inorganic nutrients for carbon and energy sources.

true

Microorganisms that live in severe habitats, such as very hot, acidic, or salty environments, are called ______.

extremophiles

When microbes are in a close nutritional relationship and one benefits but the other is not harmed, it is called ______.

commensalism

The majority of human pathogens fall into the group called ______.

mesophiles

An organism that can exist in both oxygen and oxygen-free environments is a/an ______.

facultative anaerobe

E. coli bacteria normally live in the human gut and produce vitamin K and vitamin B12 which the body uses. This is best termed a/an ______ relationship.

mutualistic

An organism that grows slowly in the refrigerator (at 4°C) but has an optimum growth temperature of 20°C is called a/an ______.

psychrotroph

The phase of the bacterial growth curve in which the rate of multiplication equals the rate of cell death is the ______.

stationary phase

An organism that uses CO2 for its carbon needs and sunlight for its energy needs would be called a ______.

photoautotroph

An organism that cannot tolerate an oxygen environment is a/an ______.

obligate anaerobe

The phase of the bacterial growth curve that shows the maximum rate of cell division is the ______.

exponential phase

The process by which a cell uses ATP to enclose a substance in its membrane, by forming a vacuole and engulfing it, is called ______.

endocytosis

This exotoxin-producing and endospore-forming bacteria __________ that lives in the soil is known to cause a life-threatening muscle infection - clostridial myonecrosis (AKA. gas gangrene).

Clostridium perfringens

The term facultative refers to _______.

the ability to exist in a wide range of conditions

An organism with a temperature growth range of 45°C to 60°C would be called a/an ______.

thermophile

A saprobe with a cell wall will utilize extracellular digestion.

true

An organism that cannot grow without oxygen is a/an ______.

obligate aerobe

An organism that can use gaseous oxygen in metabolism and has the enzymes to process toxic oxygen products is a/an ______.

aerobe

In regard to the tonicity, the honey is considered to be __________ environment, in which majority of bacteria would ___________.

hypertonic; plasmolyze (dehydrate)

All of the following could find a location in or on human body tissues suitable for growth

facultative anaerobes

mesophiles

capnophiles

anaerobes

After binary fission, daughter cells will differ genetically.

false

A microaerophile _______.

requires a small amount of oxygen but won't grow at normal atmospheric levels of oxygen

Anaerobes can be cultured in a CO2 environment.

true

What is the difference between mutualism and synergism?

In a mutualistic relationship, the organisms are dependent upon each other.

In a commensal relationship, the commensal benefits but the cohabitant is neither harmed nor benefited.

true

Phosphorus is one of the major elements needed in larger quantities by microorganisms.

true

The movement of substances from lower to higher concentration across a semipermeable membrane via a specific protein carrier and cell expenditure of energy is called ______.

active transport

______________ bacteria is the most common etiologic agent in the pathology of the otitis media and otitis externa. You can pick it up in contaminated swimming pools and hot tubs. In the hospital setting, it causes different nosocomial infections such as ventilator-associated pneumonia and various sepsis syndromes. It exhibits multiple resistances to antibiotics, antiseptics, and disinfectants making patient treatments more difficult.

Pseudomonas aeruoginosa

Which of the following microorganisms would find hypotonic conditions most damaging?

Protozoa

The time interval from parent cell to two new daughter cells is called ______.

the generation time

The cell wall will help prevent the cell from bursting in ______ conditions.

hypotonic

This microbe is photosynthetic, but in the absence of light it can use organic compounds as an energy source. Its carbon source is an organic compound. The appropriate classification for this organism would be ______.

photoheterotroph

Microorganisms require large quantities of ______ for use in cell structure and metabolism.

macronutrients

Helicobacter pylori is a causative agent of Peptic Ulcers. It is a neutrophile that survives the acidity of the host's stomach by producing _________ around itself, thereby neutralizing the environmental acidity.

ammonia

Whether an organism is a phototroph or a chemotroph depends on its source of energy.

true

What defines a chemoheterotroph in terms of its energy and carbon sources?

Uses chemical energy from organic compounds; organic compounds as the carbon source

Organisms, such as Escherichia coli, that have an optimal growth temperature around 37oC are considered to be ______________________________.

Hint: Psychrophiles, Psychrotrophs, Mesophiles, or Thermophiles.

Mesophiles

Listeria monocytogenes has been known to cause issues with human health because of its ability to survive and grow in both the refrigerator and the freezer. It can do this because the microbe is a ___________________.

Hint: Psychrophile, Psychrotroph, Mesophile, or Thermophile.

Psychrotroph

Organisms, such as Clostridiumsp., that cannot survive in an oxygen-rich environment because they lack the enzymes needed to eliminate its toxic byproducts are referred to as ______________________________.

Hint: obligate aerobe, obligate anaerobe, facultative aerobe, facultative anaerobe, aerotolerant aerobe, or aerotolerant anaerobe.

obligate anaerobe

A ______________________________, such as Mycobacterium tuberculosis, is an organism that grows best in levels of carbon dioxide that are higher than those normally found within the atmosphere.

Hint: Capnotroph, Microaerophile, Carbonphile, or Capnophile.

Capnophile

Describe the effects of hypotonic and hypertonic solutions on the bacterium Mycoplasma and compare them to the effects on a typical bacterial cell (representing the majority of bacteria). Discuss how their structural differences influence their responses.

Hint: Which bacterial type would swell (become turgid) and remain intact, swell (become turgid) and eventually burst (lyse), or dehydrate and eventually shrivel (undergo plasmolysis) in each environment?

In a hypotonic solution, a typical bacterial cell swells but remains intact due to its rigid cell wall, whereas Mycoplasma swells and may lyse because it lacks a cell wall.

In a hypertonic solution, both cells lose water and shrink, but the typical bacterium undergoes plasmolysis while Mycoplasma shrivels due to dehydration.

Unlike eukaryotic cells that must navigate the complexities of their nuclear envelope during cell division, prokaryotes have no such constraints and reproduce themselves by way of ______________________________.

Hint: The answer involves a simpler mechanism of replication than mitosis.

binary fission

Because bacteria lack a nuclear envelop, they typically have a generation time of about 30 minutes or less. This means that just one (1) bacterial cell can proliferate into ______________________________ cells in five (5) hours.

1024

During the ______________________________ phase of bacterial growth, the microbes are not yet growing and dividing because they are becoming acclimated to their new environment.

lag

A facultative halophile (a halo-tolerant organism), like Staphylococcus sp., can survive even moderately high levels of ______________________________, which would kill most other microbes.

Hint: acidity, pressure, temperature, salt, oxygen, or CO2.

salt