Question 1

are chromalveolates that commonly are found decomposing dead animals in freshwater habitats.

Accepted Answer

Water molds, also known as oomycetes, are chromalveolates that commonly decompose dead animals in freshwater habitats. Plasmodial and cellular slime molds are not decomposers of dead animals, and brown algae are marine organisms.

Question 2

Multicellular organisms evolved from three different ancestral lineages: chromalveolates,unikonts,and archaeplastids.Of these,fungi and animals evolved from two different lineages of and land plants are .

Accepted Answer

Fungi and animals evolved from the unikont lineage, while land plants evolved from the archaeplastid lineage. Chromalveolates are not ancestral lineages of these groups.

Question 3

Which of the following is a parasitic excavate that causes African sleeping sickness,a disease spread by the tsetse fly?

Accepted Answer

Trypanosoma is a parasitic excavate that causes African sleeping sickness, which is spread by the tsetse fly. Plasmodium causes malaria, paramecium is a free-living protozoan, and amoeba causes amoebiasis, which is typically spread through contaminated water or food.

Question 4

Barry Marshall and his collaborators showed that

Accepted Answer

Barry Marshall and his collaborators showed that Helicobacter pylori bacteria cause chronic gastritis and stomach ulcers.

Question 5

Evidence for the relatively close relationship of archaea to eukaryotes includes

Accepted Answer

Archaea and eukaryotes both have several kinds of relatively complex RNA polymerases, while bacteria have a single, less complex RNA polymerase. This is evidence of a closer evolutionary relationship between archaea and eukaryotes. Peptidoglycan is found in the cell walls of bacteria, but not in archaea or eukaryotes, and the absence of introns is a characteristic of bacteria, not eukaryotes or archaea. While both archaea and eukaryotes have circular DNA, eukaryotic DNA is wrapped around histone proteins, while archaeal DNA is not.

Question 6

The three diseases that represent high- priority threats as biological weapons today are

Accepted Answer

Anthrax, plague, and botulinum toxin are the three diseases that represent high-priority threats as biological weapons today according to the Center for Disease Control and Prevention (CDC) and Department of Defense (DoD). These diseases have the potential to cause widespread illness, death, and social disruption if used in a bioterrorism attack.

Question 7

Individual prokaryote cells are about eukaryote cells; collectively,all prokaryote cells on Earth .

Accepted Answer

Individual prokaryote cells are generally smaller than eukaryote cells, often about one-tenth the size. However, collectively, the total biomass of prokaryotes on Earth is estimated to be significantly larger than that of eukaryotes, potentially around ten times as much.

Question 8

One difference between gram- positive and gram- negative bacteria is

Accepted Answer

Gram-positive bacteria have a thicker layer of peptidoglycan in their cell walls which traps the crystal violet-iodine stain used in the Gram stain procedure, causing them to appear purple. Gram-negative bacteria have a thinner layer of peptidoglycan and an outer membrane, which allows for the crystal violet-iodine stain to be washed out during the decolorization step of the Gram stain procedure, causing them to appear pink.

Question 9

Chemoautotrophic bacteria obtain their carbon from and their energy from .

Accepted Answer

Chemoautotrophic bacteria obtain their energy from reactions involving inorganic chemicals and their carbon from CO2. They do not require sunlight or organic molecules as a carbon source. Methane is not necessarily a source of carbon for all chemoautotrophic bacteria.

Question 10

The main ingredient of oil is

Accepted Answer

Diatoms are a major component of phytoplankton and are one of the primary sources of organic material that, over millions of years, can transform into oil.

Question 11

Kelp,a seaweed that is anchored to the seafloor by rootlike structures and can grow to heights of 60 m,is a kind of

Accepted Answer

Kelp is a type of brown alga, not a green alga, water mold, or diatom.

Question 12

Which of the following is a member of the domain Archaea?

Accepted Answer

Methanogens are a type of Archaea, which are a group of organisms that are distinct from bacteria and eukaryotes. Spirochetes and chlamydias are both types of bacteria, and gram-positive bacteria refers to a specific group of bacteria distinguished by their cell walls.

Question 13

You collect a protist from a rotting log and grow it in a petri dish containing E.coli,which it engulfs.For a while the protists multiply as single cells.Then the E.coli run short,and the protists aggregate to form a clump,which rises up to become a stalked structure with a globular head.What kind of protist have you got?

Accepted Answer

The formation of a stalked structure with a globular head after running short of food suggests that the protist is a cellular slime mold.

Question 14

are heterotrophic protists; _ are photoautotrophic protists.

Accepted Answer

Protozoans are heterotrophic protists, while algae are photoautotrophic protists.

Question 15

Unlike archaean and eukaryote cell walls,bacterial cell walls contain a unique substance called

Accepted Answer

Only bacterial cell walls contain peptidoglycan, which is a unique substance that provides structural support and protection to the cell. Glycogen is a type of energy storage molecule found in some cells, but it is not part of the cell wall. Cellulose is a substance found in the cell walls of plants and some protists, but not in bacteria or archaea. Phospholipids are a major component of all cell membranes, but they are not unique to bacterial cell walls.

Question 16

In what way does the green alga Ulva resemble land plants?

Accepted Answer

The green alga Ulva has a complex life cycle with alternation between multicellular diploid and haploid generations, which is a characteristic shared with land plants.

Question 17

The largest group of prokaryotes is the ,which obtain both energy and carbon from .

Accepted Answer

Chemoheterotrophs obtain energy and carbon from organic molecules, which includes the largest group of prokaryotes. Photoautotrophs obtain their energy from light and carbon from inorganic molecules, while chemoautotrophs obtain both energy and carbon from inorganic molecules. Autotrophs, in general, obtain their carbon from inorganic molecules such as carbon dioxide.

Question 18

Which of the following organisms first introduced oxygen into Earth's atmosphere?

Accepted Answer

Cyanobacteria, also known as blue-green algae, were the first organisms to introduce oxygen into Earth's atmosphere through photosynthesis. This process began around 2.4 billion years ago and eventually led to the development of Earth's oxygen-rich atmosphere. Green algae and plants evolved later and also contribute to the oxygen content in the atmosphere, but cyanobacteria were the pioneers in this process. Early protozoans are not known to have played a significant role in oxygen production.

Question 19

In secondary endosymbiosis,a(n)became endosymbiotic in a(n)_ .

Accepted Answer

In secondary endosymbiosis, an autotrophic eukaryotic protist becomes endosymbiotic within a heterotrophic eukaryotic protist, leading to the formation of complex plastids.

Question 20

Intestinal gas is evidence of active _ in one's digestive tract.

Accepted Answer

Methanogens are microorganisms that produce methane gas as a byproduct of their metabolism. They are commonly found in the digestive tracts of animals, including humans. Therefore, the presence of intestinal gas indicates the activity of methanogens in the digestive tract.

Quiz 16: Microbial Life: Prokaryotes and Protists