BIOL 250 Exam 1 Study Guide
Questions with Actual Detailed
Answers 2025-2026 Updated.
Binary Fission - Answer Cell division in bacteria in which one cell divides into two cells
Why do bacterial cells not undergo mitosis and meiosis? - Answer 1) Prokaryotic cells do not
possess the machinery to produce spindle fibers and therefore cannot move chromosomes
around in the cell
2) Replication of DNA in a prokaryote does not occur in one phase, but instead occurs
continuously
3) Most bacteria have only one circular chromosome that is attached to the cell membrane
Bacteria undergo four different phases of growth. These phases, in order, are: - Answer Lag,
log, stationary, death
Which of the following can influence the length of the lag phase of growth? - Answer 1)
Conditions of the new media that bacteria is transferred to
2) Conditions of the old media that bacteria is transferred from
3) Characteristics of the individual organism
A culture of E. coli contains 1000 cells/ml with a generation time of 30 minutes. How many
organisms would be present after a period of 2 hours? - Answer 16,000 cells/ml
Why is it impossible for a culture of bacteria, in a single tube, to remain in the log phase of the
growth cycle forever? - Answer 1) Nutrients in the media are depleted as the number of
bacteria increase
2) Metabolic wastes accumulate as the number of bacteria increase
3) Space is limited as the number of bacteria increase
4) Metabolic wastes accumulate and space is limited as the number of bacteria increases
Bacterial growth is measured by estimating - Answer The number of viable cells per milliliter
of culture
Which of the following techniques rely on the concept that under the proper conditions, only
living bacteria will divide and form a visible colony on agar? - Answer Standard plate count
and serial dilution
,Which type of bacteria can grow at low temperatures (below 25°C)? - Answer Psychrophiles
E. coli is a bacteria that can grow in the presence or absence of oxygen, which would classify it
as a/an - Answer Facultative anaerobe
Which of the following types of organisms would thrive only in an environment in which there
was 85% CO2 and 15% O2? - Answer Microaerophiles
A media that has a constituent that causes an observable change in the medium when a
particular biochemical reaction takes place is known as - Answer Differential media
Chemicals such as penicillin disrupt cell wall synthesis. Penicillin is most effective against
replicating cells. In which phase of growth would you expect penicillin to be most active? -
Answer log phase
In which of the following stages of growth does new growth occur at the same rate as cell die
off? - Answer Stationary Phase
The theory of spontaneous generation states that: - Answer living organisms arise from non-
living sources.
Koch's Postulates - Answer 1) The specific causative agent must be found in every case of the
disease.
2) The disease organism must be isolated in pure culture.
3) Inoculation of a sample of the culture into a healthy, susceptible animal must produce the
same disease.
4) The disease organism must be recovered from the inoculated animal.
Many antibiotics are produced by species of _______. - Answer Fungi
Which of these statements fits best with the Germ Theory of Disease? - Answer Disease can
be spread when a microbe is passed from person to person
Louis Pasteur - Answer Disproved spontaneous generation through the use of swan-necked
flasks. Yeast selected, identified disease-causing organisms, vaccine development
o Yeast selection for desired wine flavor
o Identified 2 microorganisms that cause silkworm diseases
o 1st indiv was a vaccine (rabies)
, Carolus Linnoeus - Answer Created binomial nomenclature
Anton Van Leeuwenhoek - Answer *Father of microbiology*. Saw "animalcules" in pond
water. Scraped plaque off of teeth. 300x total magnifaction to observe living mircroorganism
Robert Hooke - Answer Built compound microscope. Coined the term "cells"
-used cork
Robert Koch - Answer Created Koch's Postulates to determine if an organism caused disease.
Coined term "pure culture"
-like evaluating cause of illness, or root of disease, identified causative agent for: Anthrax,
Tuberculosis, Cholera.
• Factors that held together the germ theory of disease
• Using them he identified certain causative angents:
• Anthrax -> Bacillus anthrosis
• TB-> Mycobacterium tb
• Cholera-> Vibrio cholera (vibrio has a comma shape, associated with a lot of water.
Bubonic Plague - Answer Caused by Yersinia pestis, found in fleas, killed about 25 million
poeople
Hippocrates - Answer Recognized the spread of illness. father of medical ethics. established
medical ethics. He associated particular signs and symptoms with certain illnesses and realized
that diseases could be transmitted from one person to another by clothing or other objects
Mosaic Laws - Answer Involved the use of sanitary practices to avoid illness
Pure Culture - Answer Culture comprised of only one type of organism
Which of the following microorganisms are acellular? - Answer Viruses
Which of the following microorganism lack a nucleus? - Answer Viruses, archaea, bacteria
Place Koch's postulates in the correct order:
1. The disease organism must be isolated in pure culture
2. The disease organism must be recovered from an inoculated animal
Questions with Actual Detailed
Answers 2025-2026 Updated.
Binary Fission - Answer Cell division in bacteria in which one cell divides into two cells
Why do bacterial cells not undergo mitosis and meiosis? - Answer 1) Prokaryotic cells do not
possess the machinery to produce spindle fibers and therefore cannot move chromosomes
around in the cell
2) Replication of DNA in a prokaryote does not occur in one phase, but instead occurs
continuously
3) Most bacteria have only one circular chromosome that is attached to the cell membrane
Bacteria undergo four different phases of growth. These phases, in order, are: - Answer Lag,
log, stationary, death
Which of the following can influence the length of the lag phase of growth? - Answer 1)
Conditions of the new media that bacteria is transferred to
2) Conditions of the old media that bacteria is transferred from
3) Characteristics of the individual organism
A culture of E. coli contains 1000 cells/ml with a generation time of 30 minutes. How many
organisms would be present after a period of 2 hours? - Answer 16,000 cells/ml
Why is it impossible for a culture of bacteria, in a single tube, to remain in the log phase of the
growth cycle forever? - Answer 1) Nutrients in the media are depleted as the number of
bacteria increase
2) Metabolic wastes accumulate as the number of bacteria increase
3) Space is limited as the number of bacteria increase
4) Metabolic wastes accumulate and space is limited as the number of bacteria increases
Bacterial growth is measured by estimating - Answer The number of viable cells per milliliter
of culture
Which of the following techniques rely on the concept that under the proper conditions, only
living bacteria will divide and form a visible colony on agar? - Answer Standard plate count
and serial dilution
,Which type of bacteria can grow at low temperatures (below 25°C)? - Answer Psychrophiles
E. coli is a bacteria that can grow in the presence or absence of oxygen, which would classify it
as a/an - Answer Facultative anaerobe
Which of the following types of organisms would thrive only in an environment in which there
was 85% CO2 and 15% O2? - Answer Microaerophiles
A media that has a constituent that causes an observable change in the medium when a
particular biochemical reaction takes place is known as - Answer Differential media
Chemicals such as penicillin disrupt cell wall synthesis. Penicillin is most effective against
replicating cells. In which phase of growth would you expect penicillin to be most active? -
Answer log phase
In which of the following stages of growth does new growth occur at the same rate as cell die
off? - Answer Stationary Phase
The theory of spontaneous generation states that: - Answer living organisms arise from non-
living sources.
Koch's Postulates - Answer 1) The specific causative agent must be found in every case of the
disease.
2) The disease organism must be isolated in pure culture.
3) Inoculation of a sample of the culture into a healthy, susceptible animal must produce the
same disease.
4) The disease organism must be recovered from the inoculated animal.
Many antibiotics are produced by species of _______. - Answer Fungi
Which of these statements fits best with the Germ Theory of Disease? - Answer Disease can
be spread when a microbe is passed from person to person
Louis Pasteur - Answer Disproved spontaneous generation through the use of swan-necked
flasks. Yeast selected, identified disease-causing organisms, vaccine development
o Yeast selection for desired wine flavor
o Identified 2 microorganisms that cause silkworm diseases
o 1st indiv was a vaccine (rabies)
, Carolus Linnoeus - Answer Created binomial nomenclature
Anton Van Leeuwenhoek - Answer *Father of microbiology*. Saw "animalcules" in pond
water. Scraped plaque off of teeth. 300x total magnifaction to observe living mircroorganism
Robert Hooke - Answer Built compound microscope. Coined the term "cells"
-used cork
Robert Koch - Answer Created Koch's Postulates to determine if an organism caused disease.
Coined term "pure culture"
-like evaluating cause of illness, or root of disease, identified causative agent for: Anthrax,
Tuberculosis, Cholera.
• Factors that held together the germ theory of disease
• Using them he identified certain causative angents:
• Anthrax -> Bacillus anthrosis
• TB-> Mycobacterium tb
• Cholera-> Vibrio cholera (vibrio has a comma shape, associated with a lot of water.
Bubonic Plague - Answer Caused by Yersinia pestis, found in fleas, killed about 25 million
poeople
Hippocrates - Answer Recognized the spread of illness. father of medical ethics. established
medical ethics. He associated particular signs and symptoms with certain illnesses and realized
that diseases could be transmitted from one person to another by clothing or other objects
Mosaic Laws - Answer Involved the use of sanitary practices to avoid illness
Pure Culture - Answer Culture comprised of only one type of organism
Which of the following microorganisms are acellular? - Answer Viruses
Which of the following microorganism lack a nucleus? - Answer Viruses, archaea, bacteria
Place Koch's postulates in the correct order:
1. The disease organism must be isolated in pure culture
2. The disease organism must be recovered from an inoculated animal
