Exam 1

_____________are specialized molecules secreted to bind ferric ion (Fe3+) and transport it into the cell.

• Aquaporins

• Siderophores

Siderophores

Other than bacterial cell wall, name one key difference between Gram positive and negative cells.

• Outer membrane

• cell wall

• Inner membrane

• DNA

Outer membrane

Viruses are not microbial cells.

True/False

True

Define barophiles, mesophiles, psychrophiles, and thermophiles.

[A] is an organism with optimal growth between 15 °C and 45 °C. [B] are microbes that can grow in extreme cold temperatures below 15 °C. [C] are species adapted to growth at high temperatures (50-80 °C). [D] are organisms that adapted to grow at overwhelmingly high pressures (up to 1000 atm).

[A] Mesophiles [B] Psychrophiles [C] Thermophiles [D] Barophiles

Transmission electron microscopy commonly has a resolution of ________ the highest resolution possible for light microscopy.

• 10,000X

• 1,000X

• 10X

• 100X

1,000X

Distinguish bacteriostatic and bactericidal.

Bactericidal inhibits the growth of microorganisms.

True/False

False

[A] are viruses that kill bacterial cells via physical contacts.

Bacteriophages

The majority of nitrogen in soil and marine environments is fixed by ___________________.

• UV light.

• E. coli.

• free-living bacteria and archaea.

free-living bacteria and archaea.

Which of these cellular components helps withstand turgor pressure?

• Cell membrane

• Cell outer membrane

• Cell inner membrane

• Cell wall

Cell wall

Bacterial biofilms are formed when nutrients are plentiful.

True/False

True

Barophiles do not require high pressure to grow.

True/False

False

Define acidophiles, alkaliphiles, and neutralophiles.

[A] are bacteria that grow between pH 5 and pH 8. [B] are bacteria and archaea that live in extremly acidic environments (pH 0-5). [C] occupy the opposite end of the pH spectrum, growing best at values ranging from pH 9 to pH 11.

[A] Neutralophiles [B] Acidophiles [C] Alkaliphiles

Based on what you have learned from one of the chapter reading assignments, give a synonym to each of the following terms.

Use one of these keys: attached; abiotic; biotic; free moving;

Sessile: [A]

Planktonic: [B]

Organic: [C]

Inorganic: [D]

[A] Attached [B] Free moving [C] Biotic [D] Abiotic

The bacterium Bacillus subtilis has a round-shaped cell.

True/False

False

List two common shapes of bacteria.

Bacilli and cocci

True/False

True

Gram-_____________ bacteria are more resistant to antibiotics.

• Positive

• Negative

Negative

Human pathogens are________________.

• mesophilic.

• thermophilic.

• psychrophilic.

Mesophilic

Biofilms are a complex, multicellular, sessile microbial community.

True/False

True

The capsule polysaccharides form a slippery mucous layer that inhibits _________________.

• osmosis.

• lysis.

• phagocytosis.

• diffusion.

phagocytosis

Name two examples of biocontrol.

Probiotics and insects.

True/False

False

What is the cellular morphology of Escherichia coli?

• Spirochete

• Rod

• Circular

• Coccobacilli

Rod

The membrane needs to remain ________ so that it can expand as cells grow larger and so that proteins needed for solute transport can be inserted into the membrane.

• rigid

• fluid

• warm

Fluid

A microbe is commonly defined as a ________ that requires a microscope to be seen.

• virus

• multicellular eukaryote

• bacterium

• living organism

• single-cellular prokaryote

living organism

Which of these cellular components helps withstand osmotic pressure?

• Cell membrane

• Cell inner membrane

• Cell outermembrane

• Cell wall

Cell membrane

Differentiate among complex, synthetic, selective, and defined media.

[A] or [B] media contain known lists of chemical components. Minimally [C] media contain only the specified nutrients essential for the growth of a given organism. [D] or rich media contain many, undefined nutrients. [E] media contain antimicrobial agent that limits the growth of certain group of microbes.

[A] Synthetic [B] defined [C] defined [D] complex [E] Selective

Describe the mechanisms employed by microbes to protect against osmotic stress. Which of these is incorrect?

• Increasing intracellular level of compatible solutes elevates cytoplasmic osmolarity without any detrimental effects, making it unnecessary for water to leave the cell.

• Cells also contain pressure-sensitive channels that can be used to leak solutes out of the cell.

• None

• The mechanosensitive channels allow small solutes to escape, lowering internal osmolarity and preventing too much water from entering the cell.

• When stranded in a hypertonic medium, bacteria try to protect their internal water from leaving the cell by synthesizing or importing compatible solutes that increase intracellular osmolarity.

None

Which of the following fix CO2?

• autotrophs

• symbionts

• heterotrophs

Autotrophs

Which of the following would be MOST appropriate to visualize viral particles being assembled inside an infected bacterial cell?

• transmission electron microscopy

• dark-field microscopy

• atomic force microscopy

transmission electron microscopy

Which of the following methods is used to to isolate pure culture?

• Dilution streaking method

• spread plate method

• complex media

Dilution streaking method

Bacteria are generally much bigger than fungi.

True/False

False

Name the shape of a cell containing the following protein(s). Use one these keys: circular; rod

FtsZ forms: [A]

FtsZ and MreB forms: [B]

[A] circular [B] rod

Compare and contrast Lazzaro Spallanzani’s, Louis Pasteur’s, and John Tyndall’s experiments that tested spontaneous generation.

[A] showed that sterilization prevent the growth of microbes and that microbes are replicated (Cell fission). He used sealed flask in his experiment. [B] proved that oxygen is required for the growth of microbial species. He used swan-necked flask in his experiment. [C] showed that heat can eliminate spores formed by microbes. These scientist were attempting to disprove the theory of spontaneous generation.

[A]  Lazzaro Spallanzani [B] Louis Pasteur [C] John Tyndall

Which of the following is a micronutrient?

• zinc

• carbon

• nitrogen

zinc

List one example to each of the following antimicrobials:

• Disinfectant: Ethanol

• Biocontrol: Bacteria

• Sterilization: Autoclave

True/False

True

Cell wall helps withstand osmotic pressure.

True/False

False

Analyze the relationship between solutes and water activity. Which of these is incorrect?

• The more solutes there are in a solution, the more water available for microbes to use for growth.

• The more solutes there are in a solution, the less water available for microbes to use for growth.

• The less solutes there are in a solution, the less water available for microbes to use for growth.

• Interactions between water and solutes in solution will lower water activity.

• All but two

• All but one

All but two

Name the Gram color of the following bacteria. Use one of these keys: purple; red

Gram-negative bacteria: [A]

Gram-positive bacteria: [B]

[A] Red [B] Purple

You have isolated a bacterium that you believe to be the causative agent of a new disease in frogs. How would you test the third of Koch’s postulates?

• Show that the bacterium is not present in healthy frogs.

• Determine the shape of the bacterial cells.

• Grow a pure culture of the bacterium outside the frog.

• Isolate the bacterium from a sick frog.

• Inject the bacteria into a healthy frog.

Inject the bacteria into a healthy frog.

Name the enzyme that is involved in metabolizing lactose in milk.

Lactase

LB agar/broth media were made during your virtual lab. Write the full name of LB: [A]

Luria Bertani

Define biofilms. Which of these is incorrect?

• Biofilms are composed of planktonic (freely moving) cells.

• Biofilms are a community of microbes growing on a solid surface.

• Biofilms are formed when food is scarce.

• Biofilms are composed of micro colonies of bacterial cells.

• They are made of multi-layers of cells.

Biofilms are composed of planktonic (freely moving) cells.

High pressures, such as 1000 ATM, are bactericidal to barosensitive organisms.

True/False

True

LB is a minimally defined medium.

True/False

False

Bacterial growth curve is demonstrated below. Name each number with a respective growth phase (1, ,2, 3, and 4). Use one of these keys: death phase; lag phase; log phase; stationary phase.

1. [A]

2. [B]

3. [C]

4. [D]

[A] Lag phase [B] Log Phase [C] Stationary phase [D] Death phase

What is the standard sterilization method for the controlled study of microbes?

• irradiation

• filter sterilization

• autoclaving

• pasteurization

• boiling

Autoclaving

The proteins embedded in a membrane require that region to be _________________.

• flexible.

• crystalline.

• negatively charged.

• hydrophobic.

Hydrophobic

Uncharged weak acids/bases can readily diffuse across cell membrane and cause pH stress.

True/False

True

Which of the following have evolved to grow in conditions extremely different from those optimal for humans?

• extremophiles

• halophiles

• psychrophiles

Extremophiles

Define antisepsis, disinfection, sanitation, and sterilization.

[A] is when all living cells, spores, and viruses are destroyed on an object. [B] is the killing or removal of disease producing organisms from inanimate surfaces. [C] removes pathogens from the surface of living tissues. [D] reduces the microbial population to safe levels and cleaning and disinfecting an object.

[A] Sterilization [B] Disinfection [C] Antisepsis [D] Sanitation

Psychrophiles are viable but not cultivable below 15°C.

True/False

False

Water can move across a membrane via passive diffusion but that movement is aided by _________.

• active transport

• siderophores

• porins

Porins

Explain why some bacteria appear purple after being Gram stained, while others appear pink?

• It is because Gram-positive bacteria have thick cell walls that pick up the stain readily.

• It is because Gram-positive bacteria have thin cell walls that pick up the stain readily.

It is because Gram-positive bacteria have thick cell walls that pick up the stain readily.

The molecule cardiolipin is found in starving microbial cells.

True/False

True

Instructions: Use your text book (chapter 4, pgs 140-142) to answer this question.

Given bacterium A has the following information, determine the final number of the cell using the formula given below:

Generation time = 30 min

Total time of incubation = 30 min

Original number of cell = 100 cfu/ml

Formula: N_t = N_o x 2n

Determine each of the following items

n = [A] generation

N_o = [B] cfu/ml

N_t = [C] cfu/ml

[A] 1 [B] 100 [C] 200

Bleach is an antiseptic chemical.

True/False

False

Probiotics can ONLY help with food digestion.

True/False

False

Carbon and cobalt are examples of macronutrients.

True/False

False

Psychrotrophs can grow at temperatures below 0 °C.

True/False

False

Who developed the germ theory of disease?

• Robert Koch

• Louis pasteur

• Antoni Leeuwenhoek

• Robert Hooke

Robert Koch

Cell membrane helps withstand turgor pressure.

True/False

False

Spores can be eliminated at 100°C.

True/False

False

The most widely used solidifying agent is ________. It is derived from seaweed.

• Starch

• Agar

Agar

The foodborne bacterium Listeria monocytogenes is ________________.

• psychrophilic.

• thermophilic.

• mesophilic.

psychrophilic