Free Kingdom Prokaryotae MCQs with Answers

391. How many organisms in the list given below are autotrophs? Lactobacillus, Nostoc, Chara, Nitrosomonas, Nitrobacter, Streptomyces, Saccharomyces, Trypanosoma, Porphyra, Wolffia.

• A. Four
• B. Five
• C. Six
• D. Three

Explanation: The autotrophs in the list given are: Nostoc Chara Porphyra Wolffia Autotrophs are organisms that can synthesize their own organic compounds using inorganic substances, such as carbon dioxide and sunlight or other forms of energy. They are capable of producing their own food through photosynthesis or chemosynthesis. The remaining organisms in the list are not autotrophs: Lactobacillus: Lactobacillus is a bacteria that is typically heterotrophic, meaning it obtains its energy from organic compounds produced by other organisms. Nitrosomonas and Nitrobacter: These are bacteria that are involved in the nitrogen cycle and are chemoautotrophs. They derive their energy from the oxidation of inorganic compounds, but they are not capable of photosynthesis. Streptomyces: Streptomyces is a genus of bacteria that is primarily decomposers and obtain their energy from breaking down organic matter. Saccharomyces: Saccharomyces is a yeast that is heterotrophic and obtains its energy from organic compounds. Trypanosoma: Trypanosoma is a parasitic protozoan that is heterotrophic and obtains its energy from consuming organic matter. Therefore, out of the organisms listed, four are autotrophs, and the remaining six are heterotrophs.

392. It occupies position near center of cell:

• A. Chromosome
• B. Plasmid
• C. Nucleoid
• D. Mitochondria

Explanation: The correct answer is the nucleoid. In prokaryotic cells, the nucleoid is the region where the cell's chromosomal DNA is concentrated. It is centrally located within the cell and is not enclosed by a membrane, unlike a nucleus in eukaryotic cells. This makes it unique to prokaryotes.Option A, Chromosome, refers to the DNA structure found within the nucleoid, not a separate entity. Option B, Plasmid, is a smaller DNA molecule that exists separately in the cytoplasm and is not centrally located. Option D, Mitochondria, are organelles found only in eukaryotic cells and thus not present in prokaryotes.

393. Cyanobacteria are_in nature.

• A. Autotroph
• B. Heterotroph
• C. Decomposer
• D. None

Explanation: The correct answer is: a) Autotroph.Cyanobacteria are classified as autotrophs because they have the capability to produce their own food through photosynthesis. They utilize sunlight to convert carbon dioxide and water into glucose and oxygen, acting as primary producers in their ecosystems. This distinguishes them from heterotrophs, which depend on other organisms for organic material, and decomposers, which break down dead organic matter. Option D is incorrect because cyanobacteria indeed have a defined mode of nutrition as autotrophs.

394. The several arrangements of cocci are based on their:

• A. Long chain of cells
• B. Types of division
• C. Shape
• D. All of the above

Explanation: The arrangements of cocci are determined by how they divide and remain connected. These arrangements include diplococcus (pairs), streptococcus (chains), staphylococcus (clusters), tetrads (groups of four), and sarcina (groups of eight). Each arrangement results from specific types of division and how the cells remain connected post-division. Therefore, the correct answer is that the arrangements are based on all these factors: long chains (as in Streptococcus), types of division, and their spherical shape. Options A, B, and C each describe only part of the picture, while Option D correctly encompasses all aspects.

395. Division of cocci in three planes results in formation of:

• A. Sacrinae
• B. Tetrad
• C. Staphylococcus
• D. All of the above

Explanation: The correct answer is Sacrinae because when cocci undergo division in three planes, they form a cubic arrangement of 8 cells. This is distinct from the other options: Tetrad occurs with division in two planes, creating a square of 4 cocci; Staphylococcus arises from random divisions resulting in irregular clusters; and All of the above is incorrect because not all arrangements are produced by division in three planes.

396. Comma shaped bacteria is:

• A. E. coli
• B. Vibrio
• C. Mycoplasma
• D. Bacillus

Explanation: The correct answer is Vibrio, which refers to bacteria that are characteristically comma-shaped. E. coli is rod-shaped, Mycoplasma can be spherical or pleomorphic due to its lack of a cell wall, and Bacillus is straight and rod-shaped. Thus, only Vibrio fits the description of being comma-shaped.

397. Which is a spiral shape bacteria?

• A. Spirochete
• B. E. coli
• C. Pseudomonas
• D. Streptococcus

Explanation: The correct answer is Spirochete because they are spiral-shaped bacteria. The spiral shape allows them to move in unique ways compared to other bacterial shapes. E. coli and Pseudomonas are both rod-shaped bacteria, while Streptococcus is spherical, forming chains, thus none of these match the spiral shape described in the question.

398. How many organisms in the list given below are Photoautotrophs? Lactobacillus, Nostoc, Chara, Nitrosomonas, Nitrobacter, Streptomyces, Saccharomyces, Trypanosoma, Porphyra, Wolffia.

• A. Four
• B. Five
• C. Six
• D. Three

Explanation: Photoautotrophs are organisms that can synthesize their own food using sunlight as an energy source. In the list provided, the photoautotrophs are:Nostoc: A cyanobacterium capable of photosynthesis.Chara: A green alga that performs photosynthesis.Porphyra: A type of red alga known for photosynthesis.Wolffia: A type of aquatic plant that is photosynthetic.The other organisms in the list are not photoautotrophs:Lactobacillus: A heterotrophic bacterium.Nitrosomonas: A chemoautotrophic bacterium involved in the nitrogen cycle, relying on inorganic compounds for energy.Nitrobacter: Similar to Nitrosomonas, it is also chemoautotrophic.Streptomyces: A heterotrophic bacterium that decomposes organic matter.Saccharomyces: A heterotrophic yeast.Trypanosoma: A parasitic protozoan that is heterotrophic.Therefore, the correct answer is that four organisms are photoautotrophs, while the rest are not.

399. A bacterium divides every 36 minutes. If a culture containing 105 cells/ml is grown for 180 minutes, what will be cell concentration after that period?

• A. 175 x 10^5 cells/ml
• B. 5 x 10^5 cells/ml
• C. 35 x 10^5 cells/ml
• D. 32 x 10^5 cells/ml

Explanation: The bacterium divides every 36 minutes. The total time given is 180 minutes. To find out how many times the bacterium divides during this period, divide 180 by 36, which equals 5. The formula for exponential growth is N(t) = N0 * 2n, where N0 is the initial number of cells, and n is the number of divisions. Here, N0 = 105 cells/ml and n = 5. Therefore, N(t) = 105 * 25 = 105 * 32 = 32 x 105 cells/ml. Thus, the correct answer is 32 x 105. The other options are incorrect as they do not account for the accurate number of divisions or exponential growth.

400. Bacterial ribosome lie in/on:

• A. Cytoplasm
• B. Nuclear membrane
• C. RER
• D. Cell Wall

Explanation: The correct answer is A) Cytoplasm, as bacterial ribosomes are found in the cytoplasm of the cell where they carry out protein synthesis.