MMI Exam 1 Study Guide

Microbes are a dominant form of life on Earth because of their population sizes. Microbiologists have estimated the number of bacterial cells to be 5 × ______.

10³⁰

Which characteristic most directly distinguishes prokaryotic cells from eukaryotic cells?

Presence of a membrane-bound nucleus

What is the correct order of microbes from smallest to largest?

Virus → bacterium → protozoan

In order of increasing complexity, the 3 major groups of microorganisms are ____.

Noncellular microbes → prokaryotic microbes → eukaryotic microbes

Bacteria can be considered the dominant form of life on Earth by these statements except one?

Bacteria are composed of eukaryotic cells

Cells that contain a nucleus are ______; cells that lack a nucleus are ______.

Eukaryotic; prokaryotic

Which statement best describes microbial diversity?

Microorganisms are found in nearly every environment on Earth

Eukaryotic organisms are grouped based upon analysis of ____.

18S rRNA

Which rRNA molecule is commonly used to study evolutionary relationships among bacteria?

16S rRNA

Which rRNA molecule is commonly used in phylogenetic studies of eukaryotic organisms?

18S rRNA

What can you say about the microorganism with a nucleus?

It is eukaryotic

Microbe with genetic material core covered with protein coat is ____.

Virus

A ______ cell has ______ but lacks ______.

Prokaryotic; a single circular chromosome; a nucleus

Bacteria inhabit all parts of the biosphere. Which statement best explains this?

They possess diverse metabolic and survival capabilities

Which group contains organisms that are generally considered noncellular?

Viruses

What type of microscope was used to produce the images below?

dark field microscope

Calculate the magnification for a 10X ocular lens used with a 100X objective lens.

1000X

Light is reflected off the surfaces of the specimen into the objective lens.

Dark-field microscopy

What two features of a microscope are essential for a microbiologist?

Magnification and resolution

Using the information from the image below, determine the magnification of the microbe.

110x

Select the order of lens used to bend light and magnify a specimen before it reaches your eyes when using a light microscope.

Condenser → objective → ocular

What type of objective produces an image with higher magnification?

100X oil immersion

A microscope has a 10X ocular lens and a 40X objective lens. What is the total magnification?

400X

Which microscope component concentrates light onto the specimen?

Condenser

Increasing magnification without improving resolution would primarily result in:

A larger but not necessarily clearer image

Why is immersion oil used with a high-power objective?

To increase the refractive index between the specimen and objective

Which microscopy technique is particularly useful for viewing specimens that have been made to fluoresce?

Fluorescence microscopy

Which technique provides contrast by using differences in refractive index within an unstained specimen?

Phase-contrast microscopy

Which type of microscopy is especially useful for observing the three-dimensional distribution of fluorescently labeled structures?

Confocal microscopy

Which microscope generally provides the highest resolution for examining very small cellular structures?

Electron microscope

Which of the following statements about the bacterial chromosome is incorrect?

It is contained in the nucleus

Identify the bacterial shape.

Spirilla

The image shown is a ______.

staphylococcus

Which bacterial organelle determines the shape of the cell?

Cell wall

Which one is not a function of the bacterial cell wall?

Regulate molecule traffic into and out of the cell

Bacteria with outer membrane containing lipopolysaccharide ______.

Have a Gram-negative cell wall

Which bacterial morphology describes spherical cells?

Coccus

Which arrangement describes spherical bacterial cells occurring in chain-like arrangement?

Streptococci

Which arrangement describes spherical bacteria arranged as doublets?

Diplococci

Which bacterial shape is characterized by a curved or comma-like appearance?

Vibrio

What is the primary structural component responsible for maintaining bacterial cell shape?

Cell wall

What is the major consequence of damage to the bacterial cell wall in a hypotonic environment?

Osmotic lysis

Which structure contains the primary genetic material of most bacteria?

Nucleoid

Which structure is found in both prokaryotic and eukaryotic cells?

Ribosome

Which feature is characteristic of a typical Gram-negative bacterial cell envelope?

Outer membrane and relatively thin peptidoglycan layer

Which feature is characteristic of Gram-positive bacteria?

A thick peptidoglycan cell wall

Which molecule is a major component of the outer membrane of Gram-negative bacteria?

Lipopolysaccharide

Which cellular structure controls movement of substances into and out of the bacterial cell?

Plasma membrane

The endomembrane system includes which combination of structures?

Nuclear envelope, RER, SER, Golgi, peroxisomes

Which cell structure likely arose according to the autogenous hypothesis?

golgi apparatus

Which of the following organelles is responsible for protein folding and packaging?

Golgi apparatus

Advantages of multicellularity include ____.

A longer life span and large organism size

Which of the following descriptions of eukaryotic cells is true?

They are 10-100X larger than prokaryotes

Lysosomes contain ____.

Acid hydrolases

The endosymbiotic hypothesis ____.

Explains the origins of mitochondria and chloroplasts

Which structure is present in plant cells but generally absent from animal cells?

Cell wall

Which molecule is a major structural component of fungal cell walls?

Chitin

Which organelle is primarily associated with protein synthesis when ribosomes are attached to its surface?

Rough ER

Which organelle is particularly involved in lipid synthesis and detoxification?

Smooth ER

Which organelle contains acid hydrolase enzymes that digest macromolecules and cellular debris?

Lysosome

Which organelle is primarily responsible for ATP production in eukaryotic cells?

Mitochondrion

Which observation provides evidence supporting the endosymbiotic hypothesis for mitochondria?

Mitochondria contain their own DNA and ribosomes

According to the endosymbiotic hypothesis, chloroplasts originated from an association involving:

An ancestral eukaryotic cell and a photosynthetic prokaryote

Mycelia are derived from tightly woven ____.

Hyphae

The ingestion of ____ produced by Aspergillus species may cause liver damage and death in humans.

Aflatoxin

What is the primary photosynthetic pigment found in all algae?

Chlorophyll a

Mushrooms, puffballs, and rusts are classified as ____.

Basidiomycota

Which group includes many common molds and yeasts?

Fungi

Yeast form in dimorphic fungi grows well at an optimum temperature of?

37°C

What pigment produced by brown algae is unique for its coloration?

Fucoxanthin

A mass of interconnected fungal hyphae is called a:

Mycelium

Which structure is responsible for photosynthesis in many algal cells?

Chloroplast

Which molecule is the primary photosynthetic pigment found across algae?

Chlorophyll a

Pediculus humanus corporis is to body lice as Pediculus humanus capitis is to:

Head lice

Which of the following infections is transmitted by the Anopheles mosquitoes?

Malaria

Which of the following helminths causes pinworm infections that can spread via oral-fecal transmission between toddlers?

Enterobius vermicularis

What is the best way to prevent infection by gastrointestinal parasitic worms?

Sanitary conditions and basic hygienewater filtration

Which parasite is commonly associated with pinworm infection?

Enterobius vermicularis

Which practice would most directly reduce transmission of many intestinal helminths?

Proper handwashing and sanitation

Which organism causes malaria?

Plasmodium

Which arthropod serves as the vector for malaria parasites?

Anopheles mosquito

Which type of parasite is characterized by a multicellular worm-like body?

Helminth

Which transmission route is particularly important for many intestinal parasites?

Fecal-oral transmission

During the lytic cycle, viral DNA can rapidly spread through a bacterial population via binary fission.

False

______ has drastically reduced the number of viral infections humans once suffered.

Immunization

The infectious agent that caused the abnormal appearance of peach is a __.

Viroid

Which of the following viruses is linked to cancer?

Human papillomavirus (HPV)

Which of the following defines the nature of viruses?

Obligate intracellular pathogens

The core of a virus particle can contain all the following nucleic acids EXCEPT ____.

Both DNA and RNA

Viral identification from a patient specimen can be accurately and rapidly performed using PCR in the clinical laboratory.

True

In a DNA virus replication cycle, self-assembly occurs in the __.

Nucleus

Viruses are not generally referred to as living things, because they ____.

Lack standard cell organelles

Which component of a virus surrounds and protects its viral nucleic acid?

Capsid

Which statement about viruses is most accurate?

Viruses require host cells for replication

A bacteriophage is a virus that infects:

Bacteria

What occurs during the lytic cycle of a bacteriophage?

Viral particles are produced and the host cell is typically lysed

Which technique can be used to rapidly detect specific viral nucleic acid sequences in a clinical specimen?

PCR

Which characteristic most strongly supports the classification of viruses as noncellular infectious agents?

They lack the cellular machinery required for independent metabolism and reproduction

Which viral structure is responsible for recognizing and attaching to host-cell receptors?

Capsid or viral attachment proteins

Which viral replication strategy involves integration of viral genetic material into the host genome?

Lysogenic cycle