Free Kingdom Prokaryotae MCQs with Answers

31. The function of a cell wall in prokaryotes is:

• A. To give cells rigidity
• B. To give specific shape
• C. To protect from osmotic lysis
• D. All of Above

Explanation: All prokaryotic cells have a stiff cell wall located underneath the capsule (if there is one). This structure maintains the 'cell's shape', protects the cell interior, and prevents the cell from bursting when it takes up water. Since the bacterial cell wall is 'thick and rigid', it will maintain the shape of the cell and also 'protect it from osmotic lysis' just like the cell wall of plants. Hence, the correct option is 'D'.

32. Which of the following is true bacteria?

• A. Archea Bacteria
• B. Cyano Bacteria
• C. Eu-bacteria
• D. Both B and C

Explanation: Eubacteria, on the other hand, encompass a wide range of bacteria that can be found in various habitats, including soil, water, and the bodies of plants and animals. They are more familiar to us and are involved in various ecological roles, including decomposition, nitrogen fixation, and some can cause diseases. So, among the options given, C. Eubacteria is the correct answer because it represents the true bacteria that are commonly encountered in many different environments and play essential roles in various biological processes.

33. Purple non-sulphur bacteria is an example of which of the following?

• A. Heterotrophic bacteria
• B. Saprotrophic bacteria
• C. Chemosynthetic bacteria
• D. Photosynthetic bacteria

Explanation: Option A: Heterotrophic bacteria is incorrect because heterotrophic bacteria are bacteria that obtain their energy from organic compounds, rather than sunlight.Option B: Saprotrophic bacteria is also incorrect because saprotrophic bacteria are bacteria that obtain their energy by decomposing dead organic matter.Option C: Chemosynthetic bacteria is also incorrect because chemosynthetic bacteria are bacteria that obtain their energy from the oxidation of inorganic compounds, rather than sunlight.OpytionD: Purple bacteria or purple photosynthetic bacteria are gram-negative proteobacteria that are phototrophic which means they are capable of producing their food via photosynthesis. They are pigmented with bacteriochlorophyll a or b, together with various carotenoids, which give them colours ranging between purple, red, brown, and orange.

34. Which of the following types of bacterial reproduction is most similar to mitosis?

• A. Transduction
• B. Transformation
• C. Binary fission
• D. Conjugation

Explanation: Option A: Transduction is the process by which genetic material is transferred from one bacterium to another by a bacteriophage (a virus that infects bacteria).Option B: Transformation is the process by which bacteria take up DNA from their environment and incorporate it into their genome.Option C: Bacteria reproduce by binary fission. In this process, the bacterium, which is a single cell, divides into two identical daughter cells. The bacterial cell then elongates and splits into two daughter cells each with identical DNA to the parent cell.Option D: Conjugation is the process by which bacteria transfer genetic material between cells by direct cell-to-cell contact.

35. Which of the following structures provides greater pathogenicity to the bacteria?

• A. Slime
• B. Cell Wall
• C. Cell Membrane
• D. Capsule

Explanation: In the question, you need to identify the structure that provides greater pathogenicity to the bacteria. While each component has some effect on bacterial pathogenicity, the slime, which is a soluble sheath of macromolecules, provides greater pathogenicity to bacteria while also protecting them from phagocytosis. Hence, Option A is the correct answer.

36. The presence of peptidoglycan in gram-positive bacteria is:

• A. 40% of dry weight
• B. 50% of dry weight
• C. 10% of dry weight
• D. 80% of dry weight

Explanation: Gram-positive bacteria have a thick peptidoglycan layer, which comprises 50% of their dry weight.

37. Which of the following statements about the systemic effect of bacterial cells is true?

• A. Gram-negative bacteria are more likely to cause systemic effects because they lack an outer membrane, which means they can more quickly infect host cells
• B. Gram-negative bacteria are more likely to cause systemic effects because their outer membrane protects them from antibiotics
• C. Both Options A and B are correct
• D. None of these options are correct

Explanation: gram-negative bacteria have thinner membranes, which allows them to resist many antibacterial medicines.

38. If lipopolysaccharides did not appear in the wall of bacteria on staining then it will be known as _.

• A. Gram-negative
• B. Gram-positive
• C. Capsule
• D. Both Gram positive & negative

Explanation: The Gram stain procedure distinguishes between Gram positive and Gram negative groups by coloring these cells red or violet. Gram positive bacteria stain violet due to the presence of a thick layer of peptidoglycan in their cell walls, which retains the crystal violet these cells are stained with. Alternatively, Gram negative bacteria stain pink, which is attributed to a thinner peptidoglycan wall, which does not retain the crystal violet during the decoloring process. Gram-positive bacteria do not contain lipopolysaccharides, but carry surface teichoic acids, lipoteichoic acids and peptidoglycan instead. The outer membrane of Gram-negative bacteria contains lipopolysaccharides, proteins, and phospholipids. The bacterial capsule is a large structure of many bacteria. It is a polysaccharide layer that lies outside the cell envelope, and is thus deemed part of the outer envelope of a bacterial cell.

39. In cocci, three plane division results in the formation of sarcina which is a?

• A. Cube of 8 cocci
• B. Square of 4 cocci
• C. Irregular structure
• D. Triangular 6 cocci

Explanation: Sarcina is a genus of gram-positive cocci bacteria in the family Clostridiaceae. The genus takes its name from the Latin word "sarcina," meaning pack or bundle, after the cuboidal (2x2x2) cellular associations they form during division along three planes. Therefore option A is correct.

40. Which of the following bacteria possesses a spherical shape?

• A. Bacillus anthracis
• B. Escherichia coli
• C. Spirillum minus
• D. Staphylococcus aureus

Explanation: Staphylococcus aureus (cocci) is a round shaped bacteria. Since it is spherical in shape therefore it is the right choice here.