chp 1

What is the role of the ocular lens?

To recreate the image in the viewer's eye

Specify which of the following is a major microbial ecosystem.

plants and animals

Based on your understanding of the chapter material and the information in the passage, which of the following correctly describe ways that microbes affect life?

1. Microbes affect oxygen availability in different habitats, both raising and lowering concentrations 2. Microbial cells are more abundant than human cells within the human body. 3. Microbes affect agricultural productivity.

Which type of microscope would allow the viewer to see ribosomes inside a cell?

A transmission electron microscope

Which of the following are limitations of antibiotics?

Antibiotics may be toxic. Antibiotics are not effective in treating viral infections. Treatment with antibiotics can lead to the emergence of resistant strains.

Why is a specimen smaller than 200 nm not visible with a light microscope?

Anything smaller than 200 nm cannot interact with visible light.

Hypothesize the most plausible reason why scientists accepted spontaneous generation for so many years.

Biology was primarily an observational science for many hundreds of years until the acceptance of the scientific method.

Why do electron microscopes have higher resolving power than light microscopes?

Electrons have a smaller wavelength than visible light, leading to higher resolution.

Which statement illustrates how the development of enrichment culture techniques by Beijerinck contributed to our knowledge of microbial diversity?

Enrichment culture technique allows targeting of specific metabolic groups by using selective nutrients and incubation conditions.

Identify which of the following situations would be harmful rather than beneficial.

Escherichia coli in ground meat

Drag the choices below to indicate whether each represents a genuine helpful or harmful role of microbes in human society.

Helpful - Used to produce products such as antibiotics Found in root nodules of legumes Used in bioremediation Form the normal human gut microbiome Harmful - Involved in food spoilage Grow as biofilms in storage tanks, ship's hulls, and drains Can be plant pathogens

Differentiate between industrial microbiology and biotechnology.

Industrial microbiology uses naturally occurring microbes to make low-cost products, while biotechnology uses genetically engineered microbes to make high-cost products.

S. aureus has been isolated from George's infected wound. To satisfy Koch's postulates, what would George's doctor need to do with the isolated S. aureus?

Inject the S. aureus into an animal, observe whether the animal gets an infection similar to George's, and isolate the same strain of S. aureus from the infection.

How does the malachite green stain enter an endospore?

It is heated.

What is meant by light rays being divergent?

It is spreading out

What is the role of lenses in microscopy?

Lenses focus either light or electrons to create a magnified image of a specimen.

Further characterization of the S. aureus isolated from George's wound reveals that the strain is MRSA. Why is George's doctor concerned that MRSA has been identified as the causative agent of George's infection?

MRSA is transmissible.

Which of the following is an example of a dye used in a simple stain?

Methylene blue

Which of the following is a lens found on electron microscopes but not on light microscopes?

Projector lens

Which of the following best states the germ theory of disease?

Some microorganisms can cause disease.

Due to their small size, microbes often must be examined using microscopy in order to visualize their structures. Specimens are often stained for viewing. Of the choices below, which one is not a good reason to stain a specimen?

Staining helps to keep microbes alive on a slide longer to view motility.

The plaque (microbial biofilm) that forms between your teeth is a highly anaerobic (oxygen-free) environment, even though the mouth is one of the most aerobic habitats in the body and most of the bacteria living there can use oxygen if it is available. Why is there no oxygen in the plaque between your teeth?

The bacteria living between the teeth have used up the oxygen.

In 1861, Pasteur conducted his now-famous experiments using flasks with long necks bent into an S-shape. Imagine that you are a scientist working in Pasteur's lab at this time. You decide to tip the flasks so that broth enters the long S-shaped neck. You then return the flask to its upright position. Predict the most likely outcome of tipping one of Pasteur's S-necked flasks.

The broth would become contaminated with microbes because they were trapped in the neck.

In a typical brightfield microscope (seen in the animation), at which point does magnification begin?

The objective lens

One of the first set of experiments to refute spontaneous generation was done in 1688 by Francesco Redi. Which of the following statements regarding Francesco Redi's experiments is true?

The results of his experiment demonstrated that living organisms are derived from other living organisms.

What happens to the light rays when they hit the specimen?

They are reflected, refracted, or absorbed by the specimen.

Which of the following is a characteristic shared by both electron and light microscopes?

They both employ the use of objective lenses.

What is the fate of the electrons that interact with a specimen in an electron microscope?

They may be absorbed, reflected, or refracted by the specimen.

How are negative stains different from other types of stains?

They stain the background, leaving the cells colorless.

What is the fundamental purpose of staining in light microscopy?

To increase the contrast and visibility of the specimen

Following an endospore stain, how does one distinguish endospores from vegetative cells?

Vegetative cells are pink, endospores are green.

Bacteria can have positive, neutral, or negative effects on humans and other macroorganisms. Which of the following would be a negative association?

a microbial biofilm in a pipeline

Arrange the following types of microorganisms in the order in which they evolved on Earth.

anaerobes, anoxygenic phototrophs, oxygenic phototrophs, aerobes, multicellular organisms

Which of the following best explains how organisms are currently placed into the three major cell lineages or domains?

analysis of ribosomal RNA genes

The step in Koch's postulates that most critically enabled him to determine that a particular microbe was the cause, and not an effect, of a particular disease was __________.

cells from a pure culture of the suspected pathogen must cause the disease in a healthy susceptible animal

Martinus Beijerinck developed the enrichment culture technique to isolate metabolically-distinct microbes from complex natural samples, like soil and water, by manipulating the

culture conditions and nutrients.

Distinguish which list of structural properties and activities are true for ALL cells.

cytoplasmic membrane, ribosomes, metabolism, evolution

Although the existence of microorganisms was surmised long before, their discovery depended upon a technological development (the microscope) in order for scientists to

make direct observations of microbes.

Like all forms of life on Earth, all microbial cells perform three major types of activities:

metabolism, growth, and evolution.

Frederick Griffith performed an experiment in which a live culture of avirulent "rough" strain Streptococcus pneumoniae bacteria were mixed with dead cells of virulent "smooth" Streptococcus pneumoniae bacteria. Subsequently, the "rough" bacteria were "transformed" into "smooth" bacteria capable of killing mice. This experiment demonstrated that

molecular genetic information can be transferred between bacterial cells.

Pasteur's experiments refuting the theory of spontaneous generation were crucial to the advancement of the field of microbiology because they led to the development of all EXCEPT which of the following?

optical isomers

Arrange Koch's postulates in the correct order.

pathogen present in all cases of disease; pathogen grown in pure culture; pathogen able to cause disease in healthy host; pathogen re-isolated

To study the evolutionary relationships of the earliest forms of life on Earth we need to examine a structure that is present in all cells and changes very slowly over time. All life on Earth was initially divided into three main Domains: the Bacteria, the Archaea, and the Eukarya, based on the similarities of their

ribosomal RNA.

Electron microscopy can produce images with much higher magnification and resolution than light microscopy due to

the shorter wavelength of an electron.