chapter 11

Which of the following statements about nitrifiers are TRUE?

they convert ammonium to nitrite

Sulfur and sulfate-reducing bacteria

Found in mud with organic material and oxidized sulfur compounds.

Which of the following statements about the economic impact of fungi is FALSE?

Fungi commonly cause serious human diseases that lead to loss of work hours.

Clostridium species

Generally in endospore form in soil, but will germinate to vegetative form when anaerobic conditions arise. Gram-positive rods.

Mycobacterium species

Generally pleomorphic (variable shape) rods that stain poorly and resist destaining due to waxy lipids in their cell wall structure. Several species cause human diseases.

Nitrifying bacteria

Gram-negative bacteria that obtain energy by oxidizing inorganic compounds like ammonia.

Hydrogen-oxidizing bacteria

Gram-negative obligate chemolithotrophs, use H2 as an energy source with O2 as a terminal electron acceptor.

Pseudomonas species

Gram-negative rods with polar flagella. Often produce pigments. Widespread in soil and water. Most are harmless, but some can be opportunistic pathogens of humans.

Sulfur-oxidizing bacteria (characteristics)

Gram-negative rods/spirals, may form filaments, obtain energy by oxidizing hydrogen sulfide and thiosulfate with O2 as a terminal electron acceptor.

Micrococcus species

Gram-positive cocci found in soil, dust particles, inanimate objects, skin; tolerates dry and moderately salty conditions.

Propionibacterium species

Gram-positive pleomorphic (irregular shaped) rods, fermenters, often used in Swiss cheese production.

Lactic acid bacteria

Gram-positive, catalase-negative, grow in aerobic environments but only ferment, producing acidic conditions

Nanoarchaea

Grows as 400 nm spheres attached to the surface of - and most likely parasitizing - the Ignicoccus species.

Which of the statements about chemotrophs is FALSE?

Lactic acid bacteria such as Lactobacillus obtain their ATP by oxidizing glucose, using lactic acid as their terminal electron acceptor.

Which of the following statements about symbiotic fungal relationships is FALSE?

Lichens are an association between a fungus and an orchid.

Thermophilic extreme acidophiles

Members grow optimally at or below pH 2. One was originally isolated from a coal waste pile. Two others were isolated inhabiting acidic areas in regions that spew sulfurous gases.

Bacteria in aquatic environments have evolved various mechanisms to maximize nutrient acquisition and retention. Why?

Most aquatic environments lack a steady supply of nutrients.

Cyanobacteria have evolved elaborate mechanisms for preventing O2 from coming into contact with the nitrogenase enzyme. Why?

Nitrogenase enzyme complexes are damaged or destroyed by O2.

Sulfur oxidizers

Obligate aerobes that use O2 as a terminal electron acceptor, generating sulfuric acid. Only grow above 50°C and at a pH between 1 and 6.

Sulfur-reducing hyperthermophiles

Obligate anaerobes that use sulfur as a terminal electron acceptor, generating H2S. Often isolated from hot sulfur-containing environments such as sulfur hot springs and hydrothermal vents. Some even have possible growth temperatures above 100°C.

Methane-generating hyperthermophiles

Oxidize H2, using CO2 as a terminal electron acceptor to yield gas. Can grow in temperatures as high as 97°C.

Thermus species

Stain Gram-negative, but have an unusual cell wall. Survive well in high heat, due to their interesting heat-resistant enzymes.

Deinococcus species

Stain Gram-positive, with an odd multilayer cell wall that lets the cells resist high levels of gamma radiation (also due to their extensive DNA repair enzyme activities).

Members of the genus Mycoplasma have no cell wall, making them somewhat unique in the microbial world. How do they prevent osmotic lysis?

Their plasma membrane is rich in sterols to help provide added strength and rigidity.

What do the pathogens Plasmodium species, Toxoplasma gondii, Cryptospirdium parvum, and Cyclospora cayetenansis have in common?

They all have apical complexes.

Check all the TRUE statements about mycorrhizae.

They increase the surface area of plant roots They are another name for fungal gardens grown by ants. they produce toxins and are pathogenic to humans. They increase the absorptive ability of plants.

Unusual movement mechanisms (example Magnetospirrilum)

Using a special type of flagellum housed within the periplasm to move through thick mud/sediment towards nutrients, or using a string of magnetic crystals in the cell to orient within the Earth's magnetic field to migrate towards nutrient-rich areas.

Corynebacterium species and Enterobacteriaceae family members are examples of _________ anaerobes, meaning that they preferentially use aerobic respiration if O2 is available, but can ferment if it is not.

facultative

helminths

flatworms absorb nutrients parasitically

The rhizobia group of microbes

form a nodule that creates an endosymbiotic relationship between legume plants and the bacterial cells.

Which of the following leads to genetic diversity?

hyphal fusion

Members of this group of microbes can break down glycogen deposited in the vaginal lining in response to estrogen. This helps to drop the pH in the area, preventing infections.

lactic acid bacteria

Which of the following statements about lichens are FALSE?

lichens are disease causing plant parasites

The apical complex (also called the apicoplast) of Apicocomplexans is unique to this group of protozoans. The organelle is a remnant that no longer functions for photosynthesis but is essential for cell survival. The apicoplast has its own genome that codes for apicoplast structures and proteins, and is well conserved across members of the apicomplexan group. Loss of the apicoplast genome in T. gondii and Plasmodium sp. results in the death of the organisms. This information is important because

medications targeting the apicoplast genome may be used for treating diseases such as malaria and toxoplasmosis.

Ascomycetes

often form lichens most common fungal group produce antibiotics such as penicillin

Chemilithotrophs

oxidize reduced inorganic chemicals to obtain energy, H2, use electron acceptor other than o2, CO2, sulfur

An organism that have a vegetative form of multinucleated amoeba-like cells that produce fungal-like spores are

plasmodial clime molds.

protozoa

plasmodium calcium carbonate shell classified by locomotion may lack mitochondria

Thriving in terrestrial environments Which of the statements is FALSE?

rhizobia transfer some of their DNA to the host plant

Agrobacterium species

stimulate tumor-like growths in plants to obtain nutrients.

Sulfur-oxidizing bacteria

sulfolobus species at surface of acidic sulfur-containing hot springs. *obligates aerobes *oxidize sulfur compounds *generate sulfuric acid

Which of the following about Agrobacterium tumefaciens is FALSE?

A. tumefaciens causes a plant disease called "root gall" that is characterized by swollen nodules on the roots of plants.

Formation of storage granules (example Thiomargarita)

Accumulation of sulfur, nitrate, phosphate, etc. within the cell's cytoplasm.

Which of the following statements about fungal structure are TRUE?

All fungi are multicellular. All fungi are unicellular. A visible mass of fungal hyphae is called a mycelium. The hyphae of parasitic fungi are called haustoria. Some fungi can be both unicellular and multicellular.

The clonal selection theory states that

B cells that recognize a given epitope multiply to form a family of cells.

Predator of other organisms (example Bdellovibrio)

Bacteria may prey upon other bacterial cells directly, form symbiotic relationships with larger eukaryotic organisms in exchange for nutrients, or reside within fish/protozoa without either harming or helping the host organisms.

Which of the following is NOT a member of the Enterobacteriaceae family (Gram-negative rods, glucose fermenters, some members motile with peritrichous flagella, some members lactose fermenting)?

C. diphtheriae

Sheathed bacteria (example Sphaerotilus)

Cells form chains encased within a tube. This plays a protective role, allowing the cells to attach to solid objects in nutritionally favorable habitats.

Which of the following relating to bacterial diversity is FALSE?

During unfavorable conditions, myxobacteria travel as a pack to a new location.

Prosthecate bacteria (example Caulobacter)

Extensions of the cytoplasm and cell wall are used to increase surface area for absorption of nutrients (and possibly for attachment to solid surfaces).

A man who had recently travelled to the Ohio River valley presented at the emergency room with non-specific respiratory symptoms, including a cough and feelings of malaise. A chest X ray was negative for tuberculosis. A sputum sample was taken and cultured. A Gram stain revealed some large (12 micrometers) round cells. Examination of the cultures revealed both mycelium and some microconidia. Based on this information, the likely cause of the infection was

a fungus

One of the most important jobs of dendritic cells is

activation of T cells by breakdown of whole antigens and presentation of antigenic epitopes on MHC molecules.

Which of the following about fungi is FALSE?

all fungi a unicellular

A unicellular microorganism was recovered from a hot spring (95°C) in Wyoming. After observation, it was determined that the microbial cells lack a nucleus, have a cell wall that lacks peptidoglycan, and have 70S ribosomes. Analysis of the plasma membrane reveals that the lipids contain long-chained branched hydrocarbons with ether linkages. Please choose the domain in which this organism would be classified, based on the description provided.

archaea

Methanogens

are a group of methane producing archaea, oxide H2 gas to generate ATP. alternatives include formate, methanol, acetate. CO2 as terminal electron acceptor. Smaller energy yield than other electron acceptors. sewage, swamps, marine, segments, rice paddies, digestive tracts.

Nitrifiers

are diverse group of gram-negatives *oxidize inorganic nitrogen compounds for energy *concern to farmers using ammonium nitrogen *can deplete water of O2 if wastes high in ammonium *two groups; usually grow in close association: ammonium oxidizers : nitrosomonas, nitrosoccocus

Basidiomycetes

asexual reproduction usually absent frequently absent spores borne on club shaped structures

Zygomycetes

cause bread spoilage spores capable of dormancy hyphae lack septa

Based on what you know about the myxobacteria, for which of the following could they serve as an experimental model?

cell to cell communications and cooperation

Negative selection in B and T lymphocytes occurs when

cells bind to self antigens too strongly.

fungi

cells walls with chitin saprophytic used to make beer and wine may be dimorpic

Slime molds and water molds are protists that were once classified as fungi. This error was made because slime and water molds often look like fungi and behave like fungi. However, at a cellular and molecular level, slime and water molds are completely unrelated to fungi. This development of similar characteristics by unrelated organisms is referred to as ______.

convergent evolution

Which of the following about algae are TRUE?

they use carbon dioxide as a carbon source they are autotrophic they use sunlight's as an energy source they may directly cause human disease algae form the basis of the aquatic food chain they may produce toxins that cause human disease their cell walls contain cellulose they are photosynthetic they are eukaryotes they lack an organized vascular system

chytrids

usually aquatic flagellated reproductive cells sometimes found in mammalian gut