MCQ on Bacteria Pdf

Bacteria MCQ with Answers Pdf:

What are Bacteria?

  • Bacteria in a broad sense are prokaryotes, which refer to a large class of primitive single cells whose nuclei are not encapsulated by a nuclear membrane and only have naked DNA called nucleoid regions (or nucleoids). 
  • Bacteria are grouped into two major groups of eubacteria and archaea.
  • Bacteria are mainly composed of cell membrane, cytoplasm, ribosome and other parts, and some bacteria also have special structures such as capsule, flagella and fimbriae. 
  • Most bacteria are between 0.5 and 5 μm in diameter. 
  • Bacteria have autotrophic and heterotrophic nutrition modes, among which the heterotrophic saprophytic bacteria are important decomposers in the ecosystem, enabling the carbon cycle to proceed smoothly. 
  • Some bacteria will fix nitrogen, so that nitrogen can be converted into the form of bioenergy utilization.

Classification of Bacteria:

  1. It can be divided into three categories according to the shape, namely: cocci, bacilli and spirochetes (including vibrio, spirochetes, helicobacter).
  2. According to the lifestyle of bacteria, it is divided into two categories: autotrophic bacteria and heterotrophic bacteria, of which heterotrophic bacteria include saprophytic bacteria and parasitic bacteria. 
  3. According to the oxygen demand of bacteria, they can be divided into aerobic (completely aerobic and microaerophilic) and anaerobic (incomplete anaerobic, aerobic tolerant and completely anaerobic) bacteria. 
  4. According to the classification of bacteria survival temperature, it can be divided into three categories: cold, normal temperature and high temperature.

Bacterial Reproduction:

  • Bacteria generally reproduce asexually by binary fission.
  • Under suitable conditions, most bacteria reproduce extremely quickly, and it takes only 20 to 30 minutes to divide once. 
  • Cocci can divide from different planes and form different arrangements after division. 
  • The generation of bacteria depends on the type of bacteria and is affected by environmental conditions. 
  • The generation of bacteria is generally 20 to 30 minutes, and the generation of individual bacteria is slower, such as 18 to 20 hours for the generation of Mycobacterium tuberculosis.
  • Bacterial division can be divided into 4 steps: the first step is nuclear replication and cell elongation; the second step is to form a diaphragm; the third step is to form a clear cell wall; the fourth step is cell division and daughter cells are separated.

Multiple Choice Questions on Bacteria and its Structure:

1. Who discovered bacteria?

A. Leeuwenhoek

B. Hook

C. Altman

D. Crick

Answer: A

2. Which type of the Cocci are called micrococcus?

A. Monococcus

B. Streptococcus


D. Staphylococcus

Answer: A

3. Anthrax is caused by the gram-positive rod named as

A. Bacillus

B. Bacillus anthracis

C. Bacillus sabtlis

D. Bacillus cereus

Answer: B 

4. Flagella in bacteria enable them to________

A. reproduce. 

B. locomote. 

C. Thrive in nutrient agar. 

D. Adhere to tissue surfaces. 

Answer: B

5. In bacteria, plasmid is

A. Extrachromosomal material

B. Main DNA

C. Non-functional DNA

D. Repetitive genes

Answer: A

6. Parasitic bacteria are predominantly___________

A. Intracellular

B. Intercellular

C. Obligate

D. None of the above

Answer: A

7. Which of the following statements explains why parasitic bacteria generally evolve faster than their hosts_______

A. Bacteria face greater choices than their hosts

B. Bacteria have less DNA than the host

C. Bacteria reproduce primarily sexually

D. The reproductive cycle of bacteria is generally shorter than that of the host

Answer: D

8. The denitrifying bacteria are________

A. Micrococcus denitrificans

B. Pseudomonas

C. Thiobacillus

D. All of the above

Answer: D

9. Which one of the following sets includes bacterial diseases?

A. Malaria, mumps, polio

B. Cholera, typhoid, mumps

C. Tetanus, TB, malaria

D. Diphtheria, leprosy, plague

Answer: D

10. Bacteria resembles_______

A. Nostoc species

B. Mitochondria

C. Chlamydomonas

D. None of the above

Answer: A

11. Which of the following bacteria is motile_______

A. S. typhi

B. K. pneumoniae

C. B. anthracis

D. Shigella

Answer: A

12. Rod-shaped bacteria are called___________

A. Vibrio

B. Cocci

C. Bacilli

D. Spirili

Answer: C

13. Which of the following statement is true about cell wall of gram-positive bacteria________

A. cell wall comprises of many layers

B. the cell wall is thicker than the associated gram-negative bacteria

C. Cell wall comprises of teichoic acids

D. All of the above

Answer: D

14. The viruses that attack bacteria are_______

A. Bacterial viruse

B. Bacterial pathogens

C. Bacteriophages

D. Various

Answer: C

15. Pili in bacteria represent_______

A. Extra chromosomal genetic element

B. Protoplasmic outgrowth of donor cells

C. Small flagella

D. Special bacterial cilia

Answer: B

16. The bacterial cell division occurs by_________

A. Mitosi

B. Meiosis

C. Conjugation

D. Binary-fission

Answer: D

17. The differences between Gram positive and Gram negative bacteria is shown to reside in the_________

A. Cell wall

B. Nucleus

C. Cell membrane

D. Mesosomes

Answer: A

18. Both types of bacteria present in salt lakes and hot springs are characterized by______

A. Reproduction of genetic material in extreme environments

B. sensitive to penicillin

C. Does not undergo fission reproduction in extreme environments

D. no cell wall

Answer: A

19. The characteristic shape of the bacteriais maintained because of

A. Capsule

B. Cell wall

C. Cell membrane

D. Slime layer

Answer: B

20. These bacteria grow anaerobically on cellulosic material, produce large amounts of methane along with carbon dioxide and hydrogen and are collectively called methanogens. Examples of such bacteria are:

A. Methanobacterium

B. Methanobrevibacter

C. Methanococcus

D. All of these

Answer: D

21. Which one of the following combinations is mismatched?

A. Glycocalyx- maybe capsule or slime layer

B. Pili- Respiration

C. Cell wall- protective, determines the shape, prevents from bursting

D. Flagella, Pili and Fimbriae- the surface structure of bacteria cell

Answer: B

22. Which organism reproduces offspring without going through meiosis and fertilization______

A. bacteria

B. rabbit

C. frog

D. wheat

Answer: A

23. Which of the following is not part of the basic structure of bacteria______

A. flagella

B. Nucleus 

C. Plasmid

D. cell wall

Answer: B

24. Which of the following cannot  occurs in bacterial reproduction_____

A. Splitting of centromeres

B. DNA replication

c. cell wall formation

D. protein synthesis

Answer: A

25. Which statement about Escherichia coli is true_______

A. Tetracycline inhibits protein synthesis in cells

B. High-producing human insulin strains can be obtained by mutation breeding

C. Cells contain only four bases A, T, C, and

G. T2 phage infects cells without causing cell lysis

Answer: A

26. The statement about nitrifying bacteria is correct:

① It contains ribosomes but not chloroplasts 

② It contains DNA and RNA, and the DNA is located on chromosomes 

③ Because it is an aerobic microorganism, it contains mitochondria 

④ Inheritance does not follow Mendel’s laws genetic mutation 

A. ②③④

B. ①④⑤

C. ①②③⑤

D. ①②④⑤

Answer: B

27. Mendel’s laws of inheritance do not apply to unicellular organisms such as bacteria, the main reason is: unicellular organisms such as bacteria

A. Genetic material is not DNA

B. Genetic material is not on chromosomes

C. Usually asexual reproduction

D. no nucleus

Answer: C

28. False statement about Bacillus anthracis_______

A. It has the structure of cell wall, cell membrane, cytoplasm and nucleoid

B. Reproduction by binary fission

C. Outside the nucleocapsid, there is an envelope composed of polysaccharides, proteins and lipids

D. Assimilation type is chemoheterotrophy

Answer: C

29. Which statement about actinomycetes is incorrect is________

A. A multicellular prokaryotic organism

B. Usually composed of branched hyphae

C. Intrabasal mycelium is related to nutrient absorption

D. Aerial hyphae are associated with sporogenesis

Answer: A

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