MICRO CHAPTER 1 - 3 - 7 - 8

What is the most common method of reproduction in bacteria?

• Budding

• Binary fission

• Sexual reproduction

• Spore formation

Answer explanation

Bacteria usually reproduce by binary fission, where one cell divides into two identical cells

What is the name of the protein that forms the Z ring during bacterial cytokinesis?

• MreB

• Crescentin

• FtsZ

• Tubulin

Answer explanation

FtsZ is a tubulin-like protein that forms the Z ring, playing a key role in septation during cell division

Which environmental factor directly affects enzyme activity in microbes?

• Pressure

• Temperature

• Color

• Shape

Answer explanation

Enzymes have optimal temperatures at which they function; high temperatures can denature enzymes

Which type of bacteria grows best at very high salt concentrations (above 2M)?

• Mesophiles

• Psychrophiles

• Halophiles

• Extreme halophiles

Answer explanation

Extreme halophiles require salt concentrations above 2M for optimal growth

Which of the following is NOT a phase in the bacterial growth curve?

• Lag phase

• Death phase

• Balance phase

• Exponential phase

Answer explanation

The bacterial growth curve includes lag, exponential, stationary, and death phases

Which bacteria require oxygen but at lower levels than atmospheric oxygen (2-10%)?

• Obligate anaerobes

• Microaerophiles

• Facultative anaerobes

• Aerotolerant anaerobes

Answer explanation

Microaerophiles require oxygen for growth but at lower concentrations (2-10%)

What is biofilm primarily made of?

• Lipids

• Polysaccharides, proteins, and DNA

• Pure water

• Carbohydrates only

Answer explanation

Biofilms are complex communities surrounded by extracellular polymeric substances (EPS)

What term describes microbes that grow optimally between pH 0 and pH 5.5?

• Acidophiles

• Thermophiles

• Alkaliphiles

• Neutrophiles

Answer explanation

Acidophiles prefer acidic environments with pH between 0 and 5.5

What method is used to isolate single colonies of bacteria on an agar plate?

• Pour plate

• Spread plate

• Streak plate

• Membrane filtration

Answer explanation

The streak plate method helps to isolate individual bacterial colonies

Which phase of microbial growth is characterized by active synthesis of enzymes but no immediate increase in cell number?

• Lag phase

• Exponential phase

• Stationary phase

• Death phase

Answer explanation

During the lag phase, cells prepare for division by synthesizing materials, but no immediate growth in number occurs