Question 1

The most ancient type of organisms on Earth originated:

Accepted Answer

The most ancient type of organisms on Earth, such as bacteria and archaea, are believed to have originated around 3.5 billion years ago, based on fossil evidence and molecular studies.

Question 2

Because they differ from all other living organisms by lacking a discrete nucleus and many other cell inclusions, Bacteria and Archaea are considered to be:

Accepted Answer

Bacteria and Archaea are considered prokaryotic because they lack a discrete nucleus and many other cellular structures that are found in eukaryotic cells.

Question 3

Which of the following is NOT true of horizontal (lateral) transfer of genetic information?

Accepted Answer

Horizontal (lateral) transfer of genetic information involves the transfer of genes between organisms in a manner other than traditional reproduction (parent to progeny), thus A is not true.

Question 4

A protein that can move protons and other ions across a cellular membrane is called a:

Accepted Answer

Proton pumps are specialized proteins found in cellular membranes that actively transport protons (H⁺ ions) across the membrane, often against their concentration gradient, using energy typically derived from ATP. This process is crucial for various cellular functions, including maintaining pH balance and driving the synthesis of ATP in mitochondria and chloroplasts.

Question 5

Which of the following characteristics do not occur in ANY cyanobacterium?

Accepted Answer

Cyanobacteria are known for their ability to undergo photosynthesis (A), sometimes produce toxins that can poison natural bodies of water (B), generate oxygen as a byproduct of photosynthesis (C), and some can detect the Earth's magnetic field (E). However, they do not generate methane (D); methane production is typically associated with archaea and some bacteria under anaerobic conditions, not cyanobacteria.

Question 6

There is great diversity of shape among microbes. Form is one of the ways different taxa can be distinguished. Which of the following shapes are not found among the microbes?

Accepted Answer

Microbes exhibit a variety of shapes, including rods (bacilli), spheres (cocci), curved shapes, and spirals. However, octagonal shapes are not a recognized form among microbes.

Question 7

Which of the following is NOT a function of slimy mucilage in microbes?

Accepted Answer

Ultraviolet radiation protection is not a function of slimy mucilage in microbes.

Question 8

Microorganisms may aggregate and glue themselves to teeth to form dental plaque. This is an example of:

Accepted Answer

A biofilm is a community of microorganisms that adhere to surfaces, such as teeth, and produce a protective and adhesive matrix. Dental plaque is a common example of a biofilm.

Question 9

Some individual microbes secrete small molecules that induce other microbes to settle nearby. The aggregation that forms responds collectively to stimuli and moves in common to new sites and secretes mucilage. This process is called:

Accepted Answer

Quorum sensing is the process through which microbes communicate and coordinate their behavior based on their population density, including aggregation and collective movement.

Question 10

Which of the following statements is NOT true of Gram-positive bacteria?

Accepted Answer

Gram-positive and Gram-negative bacteria are not classified by "gram molecular weight," but rather by their cell wall composition and response to Gram staining. The statement about gram molecular weight is incorrect and not a criterion used in distinguishing these types of bacteria.

Question 11

Flagella occur in both prokaryotes and eukaryotes. Which of the following statements DOES NOT describe how the flagella of prokaryotes and eukaryotes differ?

Accepted Answer

The filament of eukaryotic flagella is not multilayered; it is composed of microtubules arranged in a "9+2" structure, whereas prokaryotic flagella are made of a single type of protein called flagellin.

Question 12

Which of the following structures allow microbes to glide across surfaces?

Accepted Answer

Pili are hair-like structures on the surface of some bacteria that can help in movement across surfaces through a process known as "twitching motility."

Question 13

Binary fission is:

Accepted Answer

Binary fission is a method of cell division by simple splitting, commonly seen in prokaryotic organisms like bacteria. It does not involve the complex processes of mitosis or meiosis.

Question 14

Which of the following diseases is NOT caused by endospore-forming bacteria?

Accepted Answer

Pneumonia is not typically caused by endospore-forming bacteria. Botulism, anthrax, tetanus, and lockjaw (another name for tetanus) are diseases caused by endospore-forming bacteria such as Clostridium botulinum (botulism), Bacillus anthracis (anthrax), and Clostridium tetani (tetanus and lockjaw).

Question 15

The oldest spores from which bacteria have been successfully cultured were:

Accepted Answer

The correct answer is E) 250 million years old. Scientists have successfully revived bacterial spores from salt crystals that are approximately 250 million years old, making them the oldest known spores from which bacteria have been cultured.

Question 16

The process whereby genetic exchange occurs by way of viruses carrying genes from one microbe to another is known as:

Accepted Answer

Transduction is the process where bacteriophages (viruses that infect bacteria) carry genetic material from one bacterium to another, facilitating genetic exchange.

Question 17

A bacterial "bloom" is:

Accepted Answer

A bacterial "bloom" refers to a rapid increase in the population of bacteria in an aquatic environment, which can change the color of the water. This is often visible in lakes, ponds, or the sea and can be due to various factors, including excess nutrients.

Question 18

Which of the following series is arranged in the correct sequence of occurrence during the fixation and subsequent use of nitrogen?

Accepted Answer

The correct sequence starts with atmospheric nitrogen, which is then fixed into ammonia by bacterial nitrogenase. This ammonia is then converted by plants or algae into forms they can use, followed by the synthesis of proteins using the fixed nitrogen.

Question 19

Organisms that fix nitrogen are called:

Accepted Answer

Diazotrophs are organisms that fix atmospheric nitrogen into a form that is usable by plants. This process is crucial for the nitrogen cycle in ecosystems.

Question 20

A lichen is an example of:

Accepted Answer

Lichens represent a mutualistic relationship between a fungus and an alga or cyanobacterium, where both organisms benefit from living together.

Quiz 27: Bacteria and Archaea