biology MCQs - 11th class Chapter 06 Mcqs

1

Who was the first scientist to report the existence of microbes like bacteria and protozoa, calling them 'animalcules'?

A

Louis Pasteur

B

Robert Koch

C

Antonie Van Leeuwenhoek

D

Edward Jenner

2

Robert Koch formulated the 'germ theory of disease' after studying bacteria that caused which disease?

A

Anthrax

B

Fowl Cholera

C

Rabies

D

Smallpox

3

Bacteria are classified into eubacteria and which other smaller division?

A

Protobacteria

B

Archaeobacteria

C

Actinobacteria

D

Cyanobacteria

4

What is the approximate size range of the smallest bacteria, such as Mycoplasma?

A

100 to 200 µm

B

1.1 to 1.5 µm

C

0.1 to 0.5 µm

D

2.0 to 6.0 µm

5

A bacterial arrangement consisting of a square of 4 cocci is known as a:

A

Sarcina

B

Tetrad

C

Diplococcus

D

Staphylococcus

6

Which bacterial shape is described as a thick, rigid spiral?

A

Vibrio

B

Spirochete

C

Spirillum

D

Bacillus

7

In which arrangement do flagella surround the entire bacterial cell?

A

Monotrichous

B

Lophotrichous

C

Amphitrichous

D

Peritrichous

8

The protein that makes up the flagella in bacteria is called:

A

Pilin

B

Keratin

C

Flagellin

D

Peptidoglycan

9

Pili, used in the conjugation process, are primarily found on which type of bacteria?

A

Gram-positive bacteria

B

Gram-negative bacteria

C

All bacteria

D

Cyanobacteria

10

The cell envelope in bacteria collectively includes the capsule, slime, and what other structure?

A

Cell membrane

B

Cytoplasm

C

Cell wall

D

Ribosome

11

In the Gram staining procedure, Gram-positive bacteria retain the primary dye and appear what color?

A

Pink

B

Red

C

Purple

D

Green

12

What percentage of dry weight in some Gram-positive bacterial cells is composed of peptidoglycan?

A

10%

B

25%

C

50%

D

75%

13

Bacterial cell membranes differ from eukaryotic cell membranes because they lack:

A

Proteins

B

Lipids

C

Sterols like cholesterol

D

Enzymes

14

The nuclear material in a bacterial cell, which is a single, circular DNA molecule, is called the:

A

Nucleus

B

Chromosome

C

Plasmid

D

Nucleoid

15

What are the self-replicating, circular DNA molecules found in some bacteria that are not essential for growth but may carry drug resistance genes?

A

Ribosomes

B

Mesosomes

C

Plasmids

D

Granules

16

Mesosomes are invaginations of the cell membrane and are involved in DNA replication and what other process?

A

Protein synthesis

B

Photosynthesis

C

Cell division

D

Food storage

17

Spores produced within the vegetative cells are known as:

A

Exospores

B

Endospores

C

Cysts

D

Akinetes

18

Which type of bacteria synthesizes its own organic compounds from inorganic substances?

A

Heterotrophic

B

Parasitic

C

Saprophytic

D

Autotrophic

19

Photosynthetic bacteria use which compound as a hydrogen source instead of water?

A

Ammonia (NH3)

B

Methane (CH4)

C

Hydrogen Sulphide (H₂S)

D

Nitrate (NO3)

20

Bacteria that can grow either in the presence or absence of oxygen are known as:

A

Aerobic

B

Anaerobic

C

Microaerophilic

D

Facultative

21

What is the phase of the bacterial growth curve where there is rapid growth and bacteria divide at an exponential rate?

A

Lag phase

B

Log phase

C

Stationary phase

D

Decline phase

22

The transfer of genetic material from a donor bacterium to a recipient using specialized sex pili is called:

A

Binary fission

B

Transformation

C

Transduction

D

Conjugation

23

The process of using physical agents to destroy all life forms is known as:

A

Antisepsis

B

Disinfection

C

Sterilization

D

Pasteurization

24

Chemical substances used on living tissues to inhibit the growth of microorganisms are called:

A

Disinfectants

B

Antibiotics

C

Antiseptics

D

Chemotherapeutic agents

25

The term 'vaccine' was derived by Pasteur from the Latin word 'Vacca', meaning:

A

Disease

B

Cow

C

To protect

D

Medicine

26

Misuse of which antibiotic can affect the auditory nerve and cause deafness?

A

Penicillin

B

Tetracycline

C

Streptomycin

D

Erythromycin

27

Cyanobacteria were previously known as:

A

Green algae

B

Red algae

C

Brown algae

D

Blue green algae

28

The photosynthetic system of cyanobacteria resembles eukaryotes because they have chlorophyll a and what else?

A

Photosystem I

B

Photosystem II

C

Phycobilisomes

D

Chloroplasts

29

The reserve food material in cyanobacteria is stored as:

A

Starch

B

Lipids

C

Glycogen

D

Protein

30

In cyanobacteria, what are the specialized cells helpful in the fixation of atmospheric nitrogen?

A

Hormogonia

B

Akinetes

C

Trichomes

D

Heterocysts

31

What is the term for a grape-like cluster arrangement of cocci?

A

Streptococcus

B

Sarcina

C

Staphylococcus

D

Tetrad

32

A chain of rod-shaped bacteria is called:

A

Diplobacillus

B

Streptobacillus

C

Coccobacillus

D

Vibrio

33

What structure protects some bacteria from phagocytosis and provides greater pathogenicity?

A

Pili

B

Flagella

C

Slime capsule

D

Cell wall

34

Which of Koch's postulates states that a pure culture will produce the disease when inoculated into a susceptible animal?

A

First postulate

B

Second postulate

C

Third postulate

D

Fourth postulate

35

Bacteria that require a low concentration of oxygen for growth are known as:

A

Obligate aerobes

B

Facultative anaerobes

C

Microaerophilic

D

Aerotolerant

36

In the bacterial growth curve, which phase has a death rate equal to the rate of reproduction?

A

Log phase

B

Decline phase

C

Lag phase

D

Stationary phase

37

Pasteur developed vaccines for anthrax, rabies, and which other disease?

A

Tuberculosis

B

Smallpox

C

Fowl cholera

D

Diphtheria

38

Permanent discoloration of teeth in young children can be caused by the misuse of:

A

Penicillin

B

Streptomycin

C

Tetracycline

D

Aspirin

39

The components located in the thylakoid membranes of cyanobacteria that contain accessory pigments are called:

A

Phycocyanin

B

Phycobilisomes

C

Heterocysts

D

Glycogen bodies

40

Nostoc reproduces asexually by the formation of smaller pieces of filaments called:

A

Akinetes

B

Endospores

C

Hormogonia

D

Heterocysts

41

What is the primary function of pili in bacteria?

A

Motility

B

Conjugation

C

Photosynthesis

D

Respiration

42

The flexible, thin spiral-shaped bacteria are known as:

A

Spirillum

B

Vibrio

C

Spirochete

D

Bacillus

43

Which of these structures is NOT found in all bacterial cells?

A

Cell membrane

B

Ribosome

C

Cytoplasm

D

Capsule

44

Chemosynthetic bacteria oxidize inorganic compounds like ammonia and trap the released energy for their synthetic reactions. This process describes which bacteria?

A

Green sulphur bacteria

B

Purple sulphur bacteria

C

Nitrifying bacteria

D

Cyanobacteria

45

What is the term for dormant, thick-walled, desiccation-resistant forms that are not heat resistant?

A

Endospores

B

Exospores

C

Cysts

D

Akinetes

46

The largest known bacterium, Epulopiscium fishelsoni, can grow as large as:

A

100 µm

B

200 µm

C

500 µm

D

600 µm

47

A bacterial arrangement in packets of eight cells is described as a:

A

Tetrad

B

Sarcina

C

Staphylococcus

D

Streptococcus

48

The process where bacteria detect and move in response to chemical signals is called:

A

Phototaxis

B

Thermotaxis

C

Chemotaxis

D

Geotaxis

49

What is the main chemical component that distinguishes Gram-positive and Gram-negative cell walls?

A

Lipopolysaccharides

B

Teichoic acid

C

Peptidoglycan

D

Sterols

50

The cytoplasmic matrix and everything present within the plasma membrane is known as:

A

Protoplasm

B

Cytosol

C

Nucleoid

D

Protoplast