Microbiology & Biotechnology MCQ (With Explanation )- 1

1. Which immunoglobuline mostly found in Saliva is……?

A). IgM     B). IgG     C). IgE      D) IgA

2. Killer cells is part of ?

A). T cells    B). B cells   C). Monocytes   D). Macrophage

3. Negroes have high resistance to which diseases?

A). Yellow fever  B). Plague   C). AIDS    D).Pellagra

4. Causative agent for Megaloblastic anemia?

A). Ring worm   B). Fish tapeworm C). Dog tapeworm D). None of above

5. Characteristic of Clostridium tetani has after staining?

A). Cluster   B). Chain of beads  C). Safety pin  D). Drum stick

6.Negative staining give information about?

A). Flagella   B). Capsule  C). Spore    D). All

7. Which of following is capable of forming fungal ball

A). Mucor   B).Rhizopus    C). Aspergillus  D). Penicillium

8. Causative microorganism of Syphils?

A). Chalamydia   B). Treponema  C). Chlamydospores  D). Leptospira interrogans

9. The mechanism by which most fungi cause disease is?

A). Hypersensitivity   B). Lecithinase Production

C). Exotoxin production  D). Coagulase production

10. Part responsible for movement in bacteris is?

A). Capsule   B). Mesosomes  C). Pill    D). Flagella

Answer with Explanation:-

Ans 1. D  Immunoglobulin A (IgA, also referred to as sIgA) is an antibody that plays a critical role in mucosal immunity. More IgA is produced in mucosal linings than all other types of antibody combined; between three and five grams are secreted into the intestinal lumen each day. This accumulates up to 15% of the total immunoglobulin produced in the entire body.

In its secretory form, IgA is the main immunoglobulin found in mucous secretions, including tears, saliva, colostrum and secretions from the genitourinary tract, gastrointestinal tract, prostate and respiratory epithelium. It is also found in small amounts in blood. The secretory component of sIgA protects the immunoglobulin from being degraded by proteolytic enzymes, thus sIgA can survive in the harsh gastrointestinal tract environment and provide protection against microbes that multiply in body secretions.

Ans  2. A  Natural Killer Cells (or NK cells) are a type of cytotoxic lymphocyte critical to the innate immune system. The role NK cells play is analogous to that of cytotoxic T cells in the vertebrate adaptive immune response. NK cells provide rapid responses to virally infected cells and respond to tumor formation, acting at around 3 days after infection. Typically immune cells detect MHC presented on infected cell surfaces, triggering cytokine release, causing lysis or apoptosis.

Ans 3. A  Yellow fever, known historically as Yellow Jack, is an acute viral disease. In most cases symptoms include fever, chills, loss of appetite, nausea, muscle pains particularly in the back and headaches. They typically get better after several days. In some people, a toxic phase follows, in which liver damage causes yellow skin and can lead to death. Because of the increased risk of bleeding, yellow fever belongs to the group of hemorrhagic fevers.

The yellow fever virus is spread by the bite of female mosquitoes. In cities this is primarily mosquitoes of the Aedes aegypti species. It only infects primates and several species of mosquito. The virus is a 40 to 50 nm enveloped positive-sense RNA virus, the first human virus discovered and the namesake of the genus Flavivirus. The disease may be difficult to distinguish from other illnesses, especially in the early stages. To confirm a suspicious case blood sample testing via PCR is required.

Ans 4. B  Megaloblastic anemia (or megaloblastic anaemia) is an anemia (of macrocytic classification) that results from inhibition of DNA synthesis during red blood cell production.When DNA synthesis is impaired, the cell cycle cannot progress from the G2 growth stage to the mitosis (M) stage. This leads to continuing cell growth without division, which presents as macrocytosis. Megaloblastic anemia has a rather slow onset, especially when compared to that of other anemias. The defect in red cell DNA synthesis is most often due to hypovitaminosis, specifically a deficiency of vitamin B₁₂ and/or folic acid.

                                       Diphyllobothrium

Several parasites consume Vit.B12 from the host -- for their on profit. Hookworms will feed on the blood --while tapeworms will rob nutrients.

Parasites can disturb the absorption of Vit.B12 for instance

Giardia Lamblia

Diphyllobothrium latum -- fish tapeworm

Enterobius vermicularis -- pinworm
Necator americanos and Ancylostoma duodenale -- both hookworm

Diphyllobothrium is a genus of tapeworm which can cause Diphyllobothriasis in humans through consumption of raw or undercooked fish. The principal species causing diphyllobothriosis is Diphyllobothrium latum, known as the broad or fish tapeworm, or broad fish tapeworm.

Ans 5. D  

Clostridium tetani is a box-car shaped, anaerobic bacterium of the genus species Clostridium. Like other Clostridium genus species, it is Gram-positive, and its appearance on a gram stain resembles tennis rackets or drumsticks. C. tetani is found as spores in soil or in the gastrointestinal tract of animals. C. tetani produces a potent biological toxin, tetanospasmin, and is the causative agent of tetanus, a disease characterized by painful muscular spasms that can lead to respiratory failure and, in up to 40% of cases, death.

Ans 6. B   Negative Stain 

 

Purpose:  To determine morphology, arrangement and size of bacteria, that may be affected by heat fixing.

Principle: The negative stain uses the dye nigrosin, which is an acidic dye.  By giving up a proton (as an acid) the chromophore of the dye becomes negatively charged.  Because the cell wall is also negatively charged only the background around the cells will become stained, leaving the cells unstained.

Ans 7. C  An aspergilloma, also known as a mycetoma or fungus ball, is a clump of fungus which exists in a body cavity such as the lung. It is associated with the Aspergillus species, but Zygomycota and Fusarium may also form similar structures.

Aspergillus is a fungus whose spores are present in the air we breathe, but does not normally cause illness. However an individual with a weakened immune status may be susceptible to aspergillus infection.

Ans 8. B  Syphilis is a sexually transmitted infection caused by the spirochete bacterium Treponema pallidum subspecies pallidum. The primary route of transmission is through sexual contact; it may also be transmitted from mother to fetus during pregnancy or at birth, resulting in congenital syphilis.

Ans 9. A   Hypersensitivity pneumonitis (HP) is a complex syndrome caused by an exaggerated immune response to the inhalation of a large variety of organic particles. The most frequent antigens that cause HP worldwide are bird proteins (pigeon breeders' disease) and bacteria (Saccharopolyspora rectivirgula). However, fungi are also implicated in many cases, including occupational and nonoccupational outbreaks.

Molecular action of mold spores from inhalation exposure starts in the alveolar regions of the lungs. Mold particles embed themselves in the alveoli and are attacked by macrophages. Phagocytosis, engulfing and ingesting particulate matter by macrophages, is the first step when absorbing or digesting particles. Large numbers of macrophages are present on the alveolar walls. If particles are digestible, the macrophages will dissolve the particles and release the products into the lymph. Initial phases of this process, and the reactions involved, are not completely understood for mold toxins.

Ans 10. D  

A flagellum is a lash-like appendage that protrudes from the cell body of certain prokaryotic and eukaryotic cells. The word flagellum in Latin means whip. The primary role of the flagellum is locomotion but it also often has function as a sensory organelle, being sensitive to chemicals and temperatures outside the cell. Flagella are organelles defined by function rather than structure. There are large differences between different types of flagellum; the prokaryotic and eukaryotic flagella differ greatly in protein composition, structure, and mechanism of propulsion, however both are used for swimming