Free Biodiversity and Variety of Life MCQs with Answers

2911. The germ theory of diseases was formulated by _.

• A. Louis Pasteur
• B. Robert Koch
• C. Christain Gram
• D. None of above

Explanation: Germ Theory states that microorganisms known as pathogens or "germs" can lead to disease. Robert Koch determined guidelines to prove that a disease is caused by a specific organism.

2912. A type of bacterial cell that completely surrounded by flagella is called :

• A. Diplococcus
• B. Peritrichous
• C. Monotrichous
• D. A tetrad

Explanation: Bacteria can be classified according to the number of flagella on their cell wall, and peritrichous is a type will many flagella all over the cell .

2913. Which of the following statements about the systemic effect of bacterial cells are true?

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

Explanation: d) None of these options is correct.This option is the most accurate. Both Option A and Option B have inaccuracies in their statements. Gram-negative bacteria do have an outer membrane, and their systemic effects are not solely due to the absence of this membrane or its protective function against antibiotics. The systemic effects of bacterial infections depend on various factors, including the pathogenicity of the bacteria, the host's immune response, and the release of bacterial toxins.

2914. In cocci, three plane division results in formation of sarcina which is a -----------

• A. Cube of eight cocci
• B. Square of four cocci
• C. Irregular structure
• D. Triangular 6 cocci

Explanation: Option A is correct since Sarcina is a cube of 8 cocci.

2915. Under the microscope, the bacteria appear a bluish-purple colour. Which class of bacteria are on the slide?

• A. Gram-positive
• B. Gram-negative
• C. Both A and B
• D. None of these

Explanation: Correct option: A (fact) (Gram positive bacteria retain bluish purple dye when being tested). If the bacteria appear bluish-purple under the microscope, it indicates that they have retained the crystal violet stain after the Gram staining procedure. Gram-positive bacteria have a thick peptidoglycan layer in their cell wall, which allows them to retain the crystal violet stain and appear purple. Gram-negative bacteria, on the other hand, have a thinner peptidoglycan layer and are counterstained with a red or pink color. Therefore, the bacteria on the slide are most likely Gram-positive.

2916. Robert Koch discovered bacteria that cause?

• A. Tuberculosis and thyphoid
• B. Tuberculosis and measles
• C. Tuberculosis and cholera
• D. All of the above

Explanation: German physician Robert Koch was one of the founders of bacteriology. He discovered the anthrax disease cycle (1876) and the bacteria responsible for tuberculosis (1882) and cholera (1883).

2917. Who discovered the bacteria causing Tuberculosis and also developed various techniques of media preparation and maintenance of pure culture?

• A. Robert Koch
• B. Louis Pasteur
• C. Alexander Fleming
• D. Leeuwenhoek

Explanation: Robert Koch was a German scientist who discovered the causative agents for deadly diseases like tuberculosis, cholera, and anthrax. He discovered solid culture media and was the first to obtain a pure culture of bacteria.

2918. Freshwater proteroants pumped out excess water by a special structure called:

• A. Oral groove
• B. Contractive vacuole
• C. Vesicle
• D. Vacuole

Explanation: Freshwater protozoans or Protoctista pump excess water out of their body with the help of contractile vacuole because they do not have an osmoregulatory mechanism like human beings.

2919. A Dutch scientist first observed very small creatures in:

• A. Vinegar
• B. Saliva
• C. Rainwater
• D. All of these options are correct

Explanation: Small creatures were first seen by Antony Leeuwenhoek, he called these creatures animalcules.

2920. Name the vertebrates which are without jaws.

• A. Osteichthyes
• B. Cyclostomata
• C. Chondrichthyes
• D. None of these

Explanation: Cyclostomi, often referred to as Cyclostomata, is a group of vertebrates that comprises the living jawless fishes: the lampreys and hagfishes.