Chapter 27 Quiz

Which of the following is a structure that permits conjugation to occur?

sex pilus -Sex pili are specialized for holding two prokaryote cells together long enough to transfer DNA during conjugation.

Which of the following obtain energy by oxidizing inorganic substances; energy that is used, in part, to fix CO2?

chemoautotrophs -Chemoautotrophs need only an inorganic molecule like CO2 as a carbon source but obtain energy by oxidizing inorganic substances.

An ecological relationship between organisms of different species that are in direct contact can best be described as _____.

symbiotic -An ecological relationship between organisms that are in direct contact is called symbiosis.

Which of the following are responsible for many human diseases?

parasitic chemoheterotrophs -one symbiotic organism, the parasite, benefits at the expense of the host. -Chemoheterotroph must consume organic molecule for both energy and carbon.

Bioremediation is _____.

the use of organisms to remove pollutants from the environment -The use of organisms to remove pollutants from air, water, and soil is called bioremediation.

Which of the following requires ATP to function, and permits some species to respond to taxes (plural of taxis)?

flagellum

Which of the following statements is not true?

x-Only bacteria have histones associated with DNA. -Only some archaea use CO2 to oxidize H2, releasing methane. -The cell walls of archaea lack peptidoglycan. -Both archaea and bacteria generally lack membrane-enclosed organelles. -Archaea and bacteria have different membrane lipids.

Genetic variation in bacterial populations cannot result from

x- meiosis. -transformation. -transduction. -mutation. -conjugation.

The typical prokaryotic flagellum features

a complex "motor" embedded in the cell wall and plasma membrane.

Which statement is true about obligate anaerobes?

They are poisoned by O2. -Some obligate anaerobes live exclusively by fermentation; others extract chemical energy by anaerobic respiration, in which substances other than O2 accept electrons at the "downhill" end of electron transport chains.

Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?

decomposer does not involve symbiosis. aggregate with methane-consuming archaea, gut mutualist, pathogen, and skin commensalist all involve symbiosis.

The following question refers to structures found in a gram-positive prokaryotic cell. Which of the following is composed almost entirely of peptidoglycan?

cell wall -Gram positive bacteria have simple cell walls with large amount of peptidoglycans.

a prokaryote that obtains both energy and carbon as it decomposes dead organisms

Heterotroph and Chemotroph

Which of the following involves metabolic cooperation among prokaryotic cells?

-biofilms x:endospore formation binary fission photoautotrophy endotoxin release

Foods can be preserved in many ways by slowing or preventing bacterial growth. Which of these methods would not generally inhibit bacterial growth?

Closing previously opened containers: Prevents more bacteria from entering, and excludes O2.

Which of the following is an important source of endotoxin in gram-negative species?

cell wall

How does the large amount of genetic variation observed in prokaryotes arise?

1. They have extremely short generation times and large populations. 2. They can exchange DNA with many types of prokaryotes by way of horizontal gene transfer. -The short generation times and large population sizes in most prokaryotic species, coupled with their ability to exchange genes, helps to increase genetic variability beyond what we would expect in asexually reproducing organisms.

Which of the following use light energy to synthesize organic compounds from CO2?

photoautotrophs

How are archaeans most similar to bacteria?

the shape of their chromosomes and plasmids -Prokaryotes typically have circular chromosomes and plasmids

Which of the following traits do archaeans and bacteria share?

1) presence of a plasma membrane 2) lack of a nuclear envelope

The prokaryotic organisms most likely to be found living in salt ponds are the _____.

halophiles -These archaea live in salty environments such as the Dead Sea.

Which of these statements about prokaryotes is correct?
A) Genetic variation in bacteria is not known to occur, nor should it occur, because of their asexual mode of reproduction.
B) They divide by binary fission, without mitosis or meiosis.
C) Their genetic material is confined within a nuclear envelope.
D) The persistence of bacteria throughout evolutionary time is due to their genetic homogeneity (i.e., sameness).
E) Bacterial cells conjugate to mutually exchange genetic material.

B) they divide by binary fission, without mitosis or meiosis.

Many physicians administer antibiotics to patients at the first sign of any disease symptoms. Why can this practice cause more problems for these patients, and for others not yet infected?

Overuse of antibiotics can select for antibiotic-resistant strains of bacteria.

Which two structures play direct roles in permitting bacteria to adhere to each other, or to other surfaces?
1. capsules
2. endospores
3. fimbriae
4. plasmids
5. flagella

1 & 3 capsules and fimbraie (attachment pili)

Assuming that each of these possesses a cell wall, which prokaryotes should be expected to be most strongly resistant to plasmolysis in hypertonic environments?

extreme halophiles

Photoautotrophs use

light as an energy source and CO2 as a carbon source.

What is the primary ecological role of prokaryotes?

breaking down organic matter

Modes of obtaining nutrients, used by at least some bacteria, include all of the following except

heteroautotrophy.

Which statement about endotoxins is true?

Endotoxins are released only when bacteria die and their cell walls break down. -Endotoxins are a component of the outer membrane of gram-negative bacteria.

How can prokaryotes be considered to be more successful on Earth than humans?

Prokaryotes are much more numerous, have more biomass, occupy more diverse habitats, and are more diverse in metabolism.

Prokaryotic ribosomes differ from those present in eukaryotic cytosol. Because of this, which of the following is correct?

Some selective antibiotics can block protein synthesis of bacteria without effects on protein synthesis in the eukaryotic host.

Mutualism

Both symbiotic organism benefits

Commensalism

One symbiotic organism benefits while the other is neither harmed nor helped by the relationship.

Parasitism

One symbiotic organism, the parasite, benefits at the expense of the host.

Nutrient recycler or decomposers

breaks down corpses, dead vegetation, and waste products ad unlocking supplies of carbon, nitrogen, and other element essential for life.

In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf’s nonliving, waxy covering, while inhibiting the growth of other microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, it causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring decompose the plant. What is the correct sequence of ecological roles played by the bacterium in the situation described here? Use only those that apply.
1. nutrient recycler
2. mutualist
3. commensal
4. parasite
5. primary producer

2, 4, 1

Gram-positive prokaryotic cell

bacteria have simple cell walls with large amounts of peptidoglycans.

Gram-negative bacteria

-have more complex cell walls with less peptidoglycan. Generally more deadly than gram positive species. -The lipopolysaccharides on the walls of gram-negative species bacteria are often toxic, and the outer membrane protects the pathogens from the defenses of their hosts. -Gram-negative bacteria are commonly more resistant than gram gram positive species to antibiotics because the outer membrane impedes entry of the drug. (archaea)

Gram stain

a valuable tool for identifying specific bacteria based on differences in their cell wells.

Not present in all bacteria, this cell covering enables cells that possess it to resist the defenses of host organisms:

capsule

Which statement about the genomes of prokaryotes is correct?

The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleoid region.

Nucleoid Region

Region where the prokaryotic chromosome is located.

Which of these is the most common compound in the cell walls of gram-positive bacteria?

peptidoglycan

phototrophs

Organism that obtain energy from light

autotrophs

Organisms that need only an inorganic compound such as CO2 as a carbon source

chemotroph

organism that obtain energy from chemicals in their environment

heterotroph

organisms that requires at least one organic nutrient- such as glucose- as a carbon source.

Photoautotrophs

are photosynthetic organisms that harness light energy to drive the synthesis of organic compound from CO2 or other inorganic compound such as HCO3- ex. (prokaryotes – cyanbacteria_ (eukaryotes – plants and algae)

Chemoautotrophs

needs only an inorganic molecule like CO2 as a carbon source but obtain energy by oxidizing inorganic substances. Ex. (hydrogen sulfide H2S, ammonia NH3, ferrous ions FE2+) (Only Prokaryotes)

Which of the following are responsible for high levels of O2 in Earth’s atmosphere?

photoautotrophs

Photoheterotrophs

use light to generate ATP but obtain their carbon in organic form. (this mode of nutrition is restricted to a few marine and halophillic prokaryotes)

Chemoheterotrophs

must consume organic molecules for both energy and carbon. ( this nutritional mode is found widely in prokaryotes, protists, fungi, animals, and even some parasitic plants.

Which statement about the domain Archaea is false?
A) Some archaeans can inhabit solutions that are nearly 30% salt.
B) The genomes of archaeans are unique, containing no genes that originated within bacteria.
C) Genetic prospecting has recently revealed the existence of many previously unknown archean species.
D) Some archaeans are adapted to waters with temperatures above the boiling point.
E) Some archaeans can reduce CO2 to methane.

B) the genomes of archeans are unique, containing no genes that originated within bacteria.

Only certain prokaryotes can perform nitrogen fixation. Although nitrogen-fixing prokaryotes have been found in the guts of animals, conditions in most animals suppress nitrogen fixation. Thus, how do most animals gain access to fixed nitrogen?

They may ingest nitrogen fixers, they may ingest plants that harbor nitrogen fixers, or plants that absorbed nitrogen from the soil, or they may ingest other animals that have done any of those things.

The thermoacidophile, Sulfolobus acidocaldarius lacks peptidoglycan. What is likely to be true of this species?
1. It is a bacterium.
2. It is an archaean.
3. The optimal pH of its enzymes will lie above pH 7.
4. The optimal pH of its enzymes will lie below pH 7.
5. It could inhabit certain hydrothermal springs.
6. It could inhabit alkaline hot springs.

2, 4, and 5

Bacteria that live around deep-sea, hot-water vents obtain energy by oxidizing inorganic hydrogen sulfide belched out by the vents. They use this energy to build organic molecules from carbon obtained from the carbon dioxide in seawater. These bacteria are _____.

chemoautotrophs -They use inorganic molecules (in redox reactions) for energy, and carbon dioxide for carbon.

Jams, jellies, preserves, honey, and other foodstuffs with a high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment

undergo death by plasmolysis.

plasmolysis

is the process in plant cells where the cytoplasm pulls away from the cell wall due to the loss of water through osmosis. This occurs in a hypertonic solution. The reverse process, cytolysis, can occur if the cell is in a hypotonic solution resulting in a lower external osmotic pressure and a net flow of water into the cell. Through observation of plasmolysis and deplasmolysis it is possible to determine the tonicity of the cell’s environment as well as the rate solute molecules cross the cellular membrane.

Genes for the resistance of antibiotics are usually located _____.

on plasmids -Genes for the resistance of antibiotics are usually located on plasmids.

plasmids

is a small DNA molecule that is physically separate from, and can replicate independently of, chromosomal DNA within a cell. Most commonly found as small circular, double-stranded DNA molecules in bacteria, plasmids are sometimes present in archaea and eukaryotic organisms. In nature, plasmids carry genes that may benefit survival of the organism (e.g. antibiotic resistance), and can frequently be transmitted from one bacterium to another (even of another species) via horizontal gene transfer. Artificial plasmids are widely used as vectors in molecular cloning, serving to drive the replication of recombinant DNA sequences within host organisms.

Endospore

is a dormant, tough, and non-reproductive structure produced by certain bacteria from the Firmicute phylum.[1] The name "endospore" is suggestive of a spore or seed-like form (endo means within), but it is not a true spore (i.e., not an offspring). It is a stripped-down, dormant form to which the bacterium can reduce itself. Endospore formation is usually triggered by a lack of nutrients, and usually occurs in Gram-positive bacteria. In endospore formation, the bacterium divides within its cell wall. One side then engulfs the other. Endospores enable bacteria to lie dormant for extended periods, even centuries. Revival of spores millions of years old has been claimed.[2] When the environment becomes more favorable, the endospore can reactivate itself to the vegetative state. Most types of bacteria cannot change to the endospore form. Examples of bacteria that can form endospores include Bacillus and Clostridium.[3]

What is the function of fimbriae?

they are used to attach the cell to its substrate or to other prokaryotes. -They are hair-like projections that aid in attachment. They are also known as attachment pili to distinguish them from the pili used in conjugation.