Question 1

A prokaryotic cell:

Accepted Answer

Prokaryotic cells do not have a nucleus. They also lack membrane-bounded organelles and have a cell wall made of peptidoglycan, not chitin. The size of prokaryotic cells can vary, but they are generally smaller than eukaryotic cells.

Question 2

A cell membrane is not:

Accepted Answer

The cell membrane is a fluid structure, composed of a bilayer of phospholipids with embedded proteins, and has a mosaic arrangement of various molecules. It is not a rigid structure.

Question 3

Penicillin halts bacterial infections:

Accepted Answer

Penicillin interferes with the construction of the cell wall of bacteria, thereby weakening and ultimately killing the bacteria. This makes the cell membrane unstable, leading to the lysis (breakdown) of the bacterial cell. Penicillin does not stimulate a person's immune system, cause DNA mutations, or damage the cell membrane directly.

Question 4

The kingdoms in the domain Eukarya include:

Accepted Answer

The kingdoms within the domain Eukarya are Animalia, Plantae, and Protista. Choice A is incorrect as Monera is now classified within the domain Bacteria, and Animalia is included in Eukarya. Choice B is incorrect as Archaea is not part of Eukarya. Choice C is incorrect as Bacteria is not part of Eukarya. Choice D is incorrect as Bacteria is not part of Eukarya and Protista is a separate kingdom.

Question 5

The scientist (scientists)given credit for making the first record of microorganisms from observations with his (their)microscopes is (are):

Accepted Answer

Antony van Leeuwenhoek is given credit for making the first record of microorganisms from observations with his microscope. He observed microorganisms in a variety of samples, including water and dental scrapings. Although Robert Hooke is known for his work with microscopes, he did not actually observe microorganisms. Mathias Schleiden and Theodore Schwann are known for their work on cell theory, not microorganisms. Louis Pasteur is known for his work with microbiology and germ theory, but he did not make the first observation of microorganisms. Rudolf Virchow is known for his work in pathology, not microbiology.

Question 6

The original three tenets of the cell theory are:

Accepted Answer

The original three tenets of the cell theory are that all organisms are made of one or more cells, the cell is the fundamental unit of life, and all cells come from preexisting cells. Option B accurately describes these three tenets. Option A is incorrect because while it is true that all organisms have DNA, this was not one of the original tenets of the cell theory. Option C is incorrect because while all organisms are made of cells and all cells produce proteins, these were not part of the original tenets of the cell theory. Option D is incorrect because not all cells have a nucleus, only eukaryotic cells do. Option E is incorrect because while all organisms are made of one or more cells and all cells do contain DNA, the original tenets of the cell theory did not include this information.

Question 7

The three domains in the Woese system of classification are:

Accepted Answer

The Woese system of classification divides all living organisms into three domains - Archaea, Bacteria, and Eukarya. Option A and D have the same three domains, but they use different names for the same domain - Monera is now split into Archaea and Bacteria. Option B includes Protista as a domain, but the Woese system groups Protista with other organisms in the Eukarya domain. Option C has an overlap in domains, grouping Eukarya and Protista as separate domains despite the fact that Protista is a subcategory of Eukarya in this system. Therefore, the best choice is E, which accurately represents the Woese system of classification.

Question 8

Members of Archaea are often referred to as extremeophils because they live in conditions of extreme:

Accepted Answer

Archaea are known to live in extreme conditions such as high temperature (thermophiles), high salinity (halophiles), and extreme pressure (barophiles). Therefore, all options given in the question (temperature, salinity, and heat) are correct.

Question 9

The primary structural component of a cell membrane is:

Accepted Answer

The primary structural component of a cell membrane is the phospholipid molecule. The phospholipid molecules form a bilayer that makes up the basic structure of the membrane. Proteins are also an important component of the cell membrane, but they are not the primary structural component. Cholesterol molecules help to stabilize the membrane but are not the primary structural component. Enzymes and sugar molecules attached to proteins are not structural components of the membrane.

Question 10

A micrometer is:

Accepted Answer

A micrometer is one-millionth of a meter, which is 0.000001 of a meter.

Question 11

A eukaryotic cell:

Accepted Answer

A eukaryotic cell has membrane-bounded organelles, such as a nucleus, mitochondria, and endoplasmic reticulum. Prokaryotic cells, on the other hand, lack membrane-bounded organelles. Additionally, a eukaryotic cell typically does not have a cell wall with peptidoglycan as seen in bacterial cells. Eukaryotic cells can vary in size, but are generally larger than prokaryotic cells.

Question 12

Cancerous cells:

Accepted Answer

All of the listed options are correct. Cancerous cells divide uncontrollably, invade surrounding tissues by squeezing into spaces where normal cells cannot, create their own blood supply (a process called angiogenesis), and secrete biochemicals that break down surrounding healthy tissues (a process called invasion).

Question 13

The cell wall of bacteria:

Accepted Answer

All of the choices are correct. The cell wall of bacteria helps prevent the cell from bursting, protects the cell, contains peptidoglycan, and gives the bacterium a distinctive shape.

Question 14

The scientist (scientists)given credit for disproving the theory of spontaneous generation is (are):

Accepted Answer

Louis Pasteur conducted experiments in the mid-1800s that demonstrated that living organisms only arise from pre-existing living organisms, and disproved the theory of spontaneous generation. His experiments involved boiling a nutrient broth in a flask with a long neck that allowed air to enter but prevented dust and microorganisms from entering. The broth remained clear until he broke off the neck, causing microorganisms from the air to enter the flask and contaminate the broth. This experiment showed that microorganisms in the air were the source of contamination, not spontaneous generation.

Question 15

The scientist (scientists)given credit for first using the term cell to describe the basic unit of life is (are):

Accepted Answer

Robert Hooke is credited with first using the term "cell" in 1665 when he described the structure of cork under a microscope.

Question 16

The scientist (scientists)given credit for formulating the "cell theory" is (are):

Accepted Answer

Mathias Schleiden and Theodore Schwann formulated the "cell theory" in 1839. This theory states that all living organisms are composed of cells and that cells are the basic unit of life. While Hooke observed cells in cork and Leeuwenhoek observed microorganisms, they did not formulate the cell theory. Virchow contributed to the cell theory by stating that all cells arise from pre-existing cells through cell division, but he did not formulate the entire theory. Pasteur's work addressed microbial fermentation and the concept of germ theory, but did not directly contribute to the formation of the cell theory.

Question 17

The scientist (scientists)given credit for adding the third tenet (all cells come from preexisting cells)to the cell theory is (are):

Accepted Answer

Rudolf Virchow is credited with adding the third tenet to the cell theory that states "all cells come from preexisting cells". He proposed this idea in 1858, based on his observations of cell division. Robert Hooke, Antony van Leeuwenhoek, and Mathias Schleiden and Theodore Schwann are all important figures in the history of cell theory, but they did not add the third tenet. Louis Pasteur is known for his work on germ theory and pasteurization, which revolutionized microbiology, but his contributions did not directly relate to the cell theory.

Question 18

The ways by which a cell avoids surface limitations to diffusion does not include:

Accepted Answer

Having a nucleus does not affect the cell's ability to diffuse substances across its membrane, as the nucleus is enclosed by its own membrane and does not interfere with the cell membrane's functions. The other answer choices (B, C, D, E) all relate to the cell's surface area to volume ratio and how it can be increased to enhance diffusion.

Question 19

The smallest certifiable living organism is:

Accepted Answer

Mycoplasma is a bacterium that lacks a cell wall and is therefore smaller than other bacteria. It is considered the smallest certifiable living organism. Viruses and nanobes are not considered living organisms because they cannot reproduce on their own and require a host cell to do so. Giardia is a protozoan, but it is larger than Mycoplasma.

Question 20

A phospholipid molecule:

Accepted Answer

A phospholipid molecule has two parts- a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail. The hydrophilic head contains a phosphate group and a glycerol molecule that are attracted to water, while the hydrophobic tail consists of fatty acids that are repelled by water. Therefore, the correct choice is C, which states that a phospholipid molecule has a hydrophilic head that is attracted to water.

Quiz 3: The Dynamic Cell