Question 1

In addition to his work with bacteria, Louis Pasteur also suggested that something even smaller than a bacterium was the cause of rabies. What did Louis Pasteur accomplish that furthered our understanding of viral diseases?

Accepted Answer

Louis Pasteur developed a vaccine for rabies, which was the first successful vaccine for a viral disease. This helped further our understanding of viral diseases and the development of vaccines to combat them. Pasteur did not discover that viruses could be based on RNA rather than DNA, see a virus under a microscope, determine the life cycle of a virus, or invent the microscope.

Question 2

Pathogenic bacteria are becoming increasingly deadly because

Accepted Answer

Antibiotic resistance is a growing problem due to the overuse and misuse of antibiotics. This means that bacteria are becoming more difficult to treat with existing antibiotics, making them more deadly. Other options may contribute to the problem, but antibiotic resistance is the most significant factor.

Question 3

Which hypothesis suggests that both polypeptides and RNA arose at the same time?

Accepted Answer

Alexander Cairns-Smith's simultaneous evolution of polypeptides and RNA hypothesis suggests that both polypeptides and RNA arose at the same time.

Question 4

Which of the following molecules is thought to have been absent from the primitive reducing atmosphere of early Earth?

Accepted Answer

Oxygen (O2) is thought to have been absent from the primitive reducing atmosphere of early Earth.

Question 5

Which of the following scientist(s) received a Nobel Prize in Chemistry for their discovery that RNA can be both a substrate and an enzyme?

Accepted Answer

Thomas Cech and Sidney Altman received the Nobel Prize in Chemistry in 1989 for their discovery that RNA molecules can catalyze chemical reactions, making them both substrates and enzymes (also known as ribozymes).

Question 6

The hypothesis that RNA and polypeptides evolved simultaneously was proposed by

Accepted Answer

The answer of The hypothesis that RNA and polypeptides evolved...

Question 7

Which genus of bacteria causes more diseases in humans than any other?

Accepted Answer

Streptococcus bacteria cause a wide range of diseases, including strep throat, scarlet fever, pneumonia, and flesh-eating infections. Therefore, it is the genus of bacteria that causes more diseases in humans than any other.

Question 8

Microbiology is the study of microbes. Which of the following is considered a microbe?

Accepted Answer

All options listed (archae, protists, viroids, and bacteria) are considered microbes, therefore E is the correct choice.

Question 9

Although microbes are often equated with pathogens, not all are pathogenic and some help humans maintain their health. Which of the following are synthesized by bacteria that live in the human intestine?

Accepted Answer

The answer of Although microbes are often equated with pathogens,...

Question 10

Miller's laboratory experiments showed that

Accepted Answer

Miller's experiments demonstrated that organic molecules could be synthesized from inorganic precursors under conditions thought to resemble those of early Earth, specifically showing that simple organic molecules such as amino acids could be formed from primitive gases.

Question 11

Bacteria cause diseases in humans when they

Accepted Answer

Bacteria cause diseases in humans by carrying genes that code for virulence factors that allow them to harm humans. This can include factors that aid in bacterial attachment, invasion of tissues, and toxin production, among others.

Question 12

If the hypothesis that protocells arose in a "RNA world" is correct, which of the following would be necessary to shift to a "DNA world"?

Accepted Answer

Each of the listed options (A through D) describes a necessary component for the transition from an RNA world, where RNA serves as both the genetic material and catalytic molecules, to a DNA world, where DNA becomes the primary genetic material. This transition would require mechanisms to convert RNA to DNA (including changing ribose to deoxyribose), replicate DNA, and transcribe DNA back into RNA for protein synthesis.

Question 13

Which of the following forms of energy is thought to have been involved in the production of large organic molecules in the primitive reducing atmosphere?

Accepted Answer

All of the answer choices could have potentially contributed to the production of large organic molecules in the primitive reducing atmosphere on early Earth. Radioactivity and heat from the Earth's core could have provided energy for chemical reactions, electrical energy could have been generated by lightning, and radiation from the sun could have contributed to the energy input as well. Therefore, it is likely that a combination of these energy sources contributed to the production of large organic molecules during early Earth's history.

Question 14

The protein-first hypothesis

Accepted Answer

The protein-first hypothesis posits that early proteins (or polypeptides) were the first molecules to give rise to life, suggesting that sophisticated enzymes capable of synthesizing nucleic acids like DNA and RNA evolved from simpler molecules available in the prebiotic world, such as those found in the ocean. This contrasts with the RNA world hypothesis, which proposes RNA as the first self-replicating molecule.

Question 15

Louis Pasteur conducted an experiment to answer the question of whether or not living things can arise spontaneously from nonliving materials. In this experiment, he used two flasks of sterile broth. What were the results of this experiment?

Accepted Answer

Pasteur's experiment showed that living things came from outside the sterile broth and did not arise spontaneously from nonliving materials. The flask with the curved neck did not allow outside air (and any potential microorganisms) to enter, therefore no growth occurred. However, growth did occur in the other flask that allowed outside air to enter, demonstrating that living things came from outside the sterile broth.

Question 16

The fact that a nucleic acid is a very complicated molecule suggests that

Accepted Answer

The complexity of nucleic acids implies that their synthesis likely required catalytic assistance, such as that from enzymes, rather than occurring purely by chance. This does not rule out the RNA-first hypothesis but suggests a more complex prebiotic chemistry.

Question 17

Which of the following is the correct order, from simple to complex, showing the origin of life?

Accepted Answer

The correct order from simple to complex in the origin of life starts with the basic elements (carbon, hydrogen, oxygen, nitrogen - C, H, O, N), which combine to form amino acids. These amino acids then link together to form proteins, which are crucial for the structure and function of living organisms. The placeholders (CH₄ and NH₃) likely represent complex biological structures or systems that would come after proteins in the hierarchy of biological complexity.

Question 18

The synthesis of DNA or RNA from the organic soup would have been guided by the actions of enzymes in the

Accepted Answer

The answer of The synthesis of DNA or RNA from...

Question 19

What form of energy did the electric spark in the Miller-Urey experiment simulate?

Accepted Answer

The electric spark in the Miller-Urey experiment was meant to simulate lightning, which is a source of energy that could have been present in the early Earth's atmosphere.

Question 20

Bacteria can be beneficial in which of the following ways?

Accepted Answer

All of the answer choices describe ways that bacteria can be beneficial, including bioremediation, industrial applications, crowding out harmful bacteria, and wastewater purification.

Quiz 28: Microbiology