Question 1

Which of the following traits do archaeans and bacteria share?
1)composition of the cell wall
2)presence of plasma membrane
3)lack of a nuclear envelope
4)identical rRNA sequences

Accepted Answer

Both archaeans and bacteria have a plasma membrane and lack a nuclear envelope. However, the composition of their cell walls can differ, and their rRNA sequences are not identical.

Question 2

Match the numbered terms to the description that follows.Choose all appropriate terms.
1)autotroph
2)heterotroph
3)phototroph
4)chemotroph
Description: an organism that relies on photons to excite electrons within its membranes

Accepted Answer

Phototrophs are organisms that rely on photons to excite electrons within its membranes, and this is the only choice that fits this description. Autotrophs create their own food through photosynthesis, and chemotrophs obtain energy from chemicals, while heterotrophs obtain energy by consuming organic matter. Therefore, choices A, C, D, and E are incorrect.

Question 3

You have found a new prokaryote.What line of evidence would support your hypothesis that the organism is a cyanobacterium?

Accepted Answer

Cyanobacteria are known for their ability to form colonies and produce oxygen through photosynthesis. This is a defining characteristic of this group of bacteria, so if the new prokaryote also has these traits, it is likely a cyanobacterium.

Question 4

Carl Woese and collaborators identified two major branches of prokaryotic evolution.What was the basis for dividing prokaryotes into two domains?

Accepted Answer

Woese and his collaborators used genetic characteristics, specifically ribosomal RNA sequences, to divide prokaryotes into two domains: Bacteria and Archaea. This was because ribosomal RNA is highly conserved across all living organisms, making it a useful tool for studying evolutionary relationships.

Question 5

Regarding prokaryotic genetics,which statement is correct?

Accepted Answer

Mutation is a primary source of variation in prokaryote populations, as they do not undergo meiosis and sexual reproduction. Prokaryotes can still exchange genetic material through horizontal gene transfer via conjugation, transduction, and transformation, but mutation is the primary mechanism for generating genetic diversity. Option A is incorrect as crossing over only occurs during meiosis in eukaryotes. Option B is incorrect as prokaryotes do not have gametes or fertilization. Option C is partially correct, but it incorrectly refers to the union of haploid gametes in prokaryotes. Option E is also incorrect as prokaryotes do not have a distinct sexual life cycle.

Question 6

If archaeans are more closely related to eukaryotes than to bacteria,then which of the following is a reasonable prediction?

Accepted Answer

The larger ribosomes are a characteristic of eukaryotes, and since archaeans are more closely related to eukaryotes than to bacteria, it is reasonable to predict that archaeal ribosomes should be larger than typical prokaryotic ribosomes. The other options are not necessarily related to the evolutionary relationship between archaeans and eukaryotes.

Question 7

We have overwhelming evidence that Bacteria and Archaea are masters of adaptation.Which key characteristic enables these prokaryotes to occupy almost every habitat on earth?

Accepted Answer

Prokaryotes have a wide range of metabolic pathways that allow them to utilize various organic and inorganic compounds for energy and growth. This metabolic diversity enables them to adapt to different environmental conditions and occupy almost every habitat on earth. Small size, fast reproductive rate, high mutation rate, and presence of a protective cell wall are also important characteristics of prokaryotes, but do not fully explain their ability to adapt to a wide range of environments.

Question 8

Match the numbered terms to the description that follows.Choose all appropriate terms.
1)autotroph
2)heterotroph
3)phototroph
4)chemotroph
Description: an organism that obtains both carbon and energy by ingesting prey

Accepted Answer

Heterotrophs obtain carbon by ingesting other organisms and energy from the organic molecules in those organisms. Chemotrophs obtain energy by oxidizing chemical compounds and may obtain carbon from either organic or inorganic sources. Autotrophs obtain carbon from inorganic sources like carbon dioxide and energy from either sunlight (phototrophs) or chemical compounds (chemotrophs). Since this description specifically mentions ingestion, it rules out phototrophs and leaves us with heterotrophs and chemotrophs. Therefore, the best choice(s) are D (heterotroph and chemotroph).

Question 9

Match the numbered terms to the description that follows.Choose all appropriate terms.
1)autotroph
2)heterotroph
3)phototroph
4)chemotroph
Description: a prokaryote that obtains both energy and carbon as it decomposes dead organisms

Accepted Answer

The description fits a heterotroph, which obtains energy by consuming other organisms or organic matter, and a chemotroph, which obtains energy through chemical reactions. Autotrophs, on the other hand, produce their own organic matter using energy from the sun (phototrophs) or chemical reactions (chemotrophs). Therefore, options C and E are incorrect, as they include autotrophs, and option B is incorrect, as it only includes chemotrophs. The correct answer is D, as it includes both heterotrophs and chemotrophs.

Question 10

Extreme halophiles

Accepted Answer

Extreme halophiles are microorganisms that live in highly saline (salty) environments, such as the Dead Sea or salt flats. They are able to survive in these extreme conditions by adapting to the high salt concentration.

Question 11

Which statement about the domain Archaea is true?

Accepted Answer

Recent genetic prospecting has indeed revealed the existence of many previously unknown archaean species. Option B is incorrect as there are certain archaeans that can reduce CO₂ to methane. Option C is incorrect as archaeans do contain genes that originated within bacteria. Option D is incorrect as there are many archaeans that inhabit environments with high salt concentrations. Option E is incorrect as there are many archaeans that are adapted to extreme temperatures, including those above the boiling point.

Question 12

Which of the following is least associated with the others?

Accepted Answer

Binary fission is a method of asexual reproduction for prokaryotes, while the other choices all involve some form of gene transfer or exchange between individuals.

Question 13

All the following are correct about antibiotic resistance,except

Accepted Answer

The answer of All the following are correct about antibiotic...

Question 14

In Fred Griffith's experiments,harmless R strain pneumococcus became lethal S strain pneumococcus as the result of which of the following?
1)horizontal gene transfer
2)transduction
3)conjugation
4)transformation
5)genetic recombination

Accepted Answer

The answer of In Fred Griffith's experiments,harmless R strain pneumococcus...

Question 15

Which of these statements about prokaryotes is correct?

Accepted Answer

Prokaryotes divide by binary fission, which is a type of asexual reproduction where one cell divides into two identical daughter cells. Unlike eukaryotic cells, they do not undergo mitosis or meiosis. Choice A is incorrect because bacterial conjugation involves the transfer of genetic material from one bacterial cell to another through a pilus, but it is not a mechanism of sexual reproduction. Choice B is partially correct, as plasmids are small, circular DNA molecules that can replicate independently from the bacterial chromosome, but not all genetic material is confined within plasmids. Choice D is incorrect because although bacteria may have similar genetic makeup, genetic variation can occur through mechanisms such as mutation and horizontal gene transfer. Choice E is also incorrect because genetic variation does occur in bacteria despite their asexual mode of reproduction.

Question 16

Hershey and Chase performed an elegant experiment that convinced most biologists that DNA,rather than protein,was the genetic material.This experiment subjected bacteria to the same gene transfer mechanism as occurs in

Accepted Answer

Hershey and Chase's experiment involved using bacteriophages (viruses that infect bacteria) to show that DNA is the genetic material transferred to bacteria during infection, a process known as transduction.

Question 17

Which of the following describe all existing bacteria?

Accepted Answer

All existing bacteria are small in size, found everywhere, and have a wide range of metabolic capabilities. While some bacteria are pathogenic, not all bacteria fall into this category. Similarly, while some bacteria are extremophiles (able to survive in extreme environments), this is not true of all bacteria. Morphological diversity is also present but not universal among bacteria.

Question 18

Mitochondria are thought to be the descendants of certain alpha proteobacteria.They are,however,no longer able to lead independent lives because most genes originally present on their chromosome have moved to the nuclear genome.Which phenomenon accounts for the movement of these genes?

Accepted Answer

Horizontal gene transfer is the movement of genes between organisms without the inheritance from a parent. It is a mechanism of genetic exchange that enables unicellular organisms to acquire novel capabilities. This process could account for the movement of genes from mitochondria to the nuclear genome during evolution.

Question 19

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

Accepted Answer

Chemoautotrophs obtain energy by oxidizing inorganic substances and use this energy, in part, to fix CO₂. The other choices obtain energy from different sources and have different methods of carbon fixation.

Question 20

Biologists sometimes divide living organisms into two groups: autotrophs and heterotrophs.These two groups differ in ________.

Accepted Answer

Autotrophs are organisms that can produce their own organic compounds, such as sugars and amino acids, from inorganic sources like carbon dioxide and water. They do this through photosynthesis or chemosynthesis. Heterotrophs, on the other hand, cannot make their own organic compounds and must consume other organisms for their nutrients. They may do this through ingestion, absorption, or symbiosis. The source of energy and the electron acceptors may vary for both autotrophs and heterotrophs, but the key difference is in their mode of nutrition.

Quiz 27: Bacteria and Archaea

Which of the following traits do archaeans and bacteria share? 1) composition of the cell wall 2) presence of plasma membrane 3) lack of a nuclear envelope 4) identical rRNA sequences

Match the numbered terms to the description that follows.Choose all appropriate terms. 1) autotroph 2) heterotroph 3) phototroph 4) chemotroph Description: an organism that relies on photons to excite electrons within its membranes