The daily requirement of vitamin B12 is:

 # The daily requirement of vitamin B12 is: 

A. 0.25-0.67 mcg per day

B. 3-5 mcg per day

C. 0.5-0.7 mcg per day

D. 1-2 mcg per day

The correct answer is D. 1-2 mcg per day.

Vitamin B12 plays a crucial role in maintaining healthy nerve function, supporting red blood cell production, and aiding in DNA synthesis. This range is in line with the daily recommended intake for vitamin B12 for most adults, which is typically around 2.4 mcg per day according to various health guidelines.

Organism most commonly seen in lung abscesses is:

 # Organism most commonly seen in lung abscesses is: 

A. Candida albicans 

B. Herpes zoster virus 

C. Oropharyngeal flora 

D. Staphylococcus aureus

(PSC KOSHI 2081)

The correct answer is C. Oropharyngeal flora. 

Lung abscesses are typically caused by aspiration of bacteria from the oropharyngeal flora. This flora includes a mix of aerobic and anaerobic bacteria normally found in the mouth and throat. When these bacteria are aspirated into the lungs, they can cause an infection leading to a lung abscess.

While the other options listed can cause infections in the lungs, they are not the most common cause of lung abscesses:

Candida albicans (A): This fungus is a common cause of opportunistic infections, but it is not the most common cause of lung abscesses.

Herpes zoster virus (B): This virus causes shingles and can rarely lead to lung complications, but it is not a common cause of lung abscesses.

Staphylococcus aureus (D): While this bacterium can cause pneumonia and other lung infections, it is not the most common cause of lung abscesses.

Tetany is caused by:

 # Tetany is caused by:

A. Hyperglycemia 

B. Hypocalcemia 

C. Clostridium tetani 

D. Low oxygen level

The correct answer is B. Hypocalcemia.

Tetany is a condition characterized by involuntary muscle contractions, cramps, and spasms. The primary cause of tetany is hypocalcemia, which is a low level of calcium in the blood. Calcium plays a crucial role in muscle contraction and nerve function. When calcium levels are low, nerves become hyperexcitable, leading to the uncontrolled muscle contractions seen in tetany.

Hyperglycemia (A): High blood sugar levels are associated with diabetes, not tetany.

Clostridium tetani (C): This bacterium causes tetanus, a different condition characterized by muscle stiffness and spasms.

Low oxygen level (D): While low oxygen can cause various symptoms, it is not the primary cause of tetany.

Reference: Hypocalcemia and Tetany: Causes, Symptoms, and Treatment (webmd.com)

Intrusion of tooth is resisted by:

 # Intrusion of tooth is resisted by:

A. Apical and interradicular fibers

B. Oblique and horizontal fibers

C. Alveolar crest and oblique fibers

D. All Periodontal fibers

The correct answer is C. Alveolar crest and oblique fibers.

The principal fibers of periodontal ligament are arranged in six groups and are named according to their

location and direction of attachment. 

1. Transseptal group

Location: These fibers run into the interproximal space over the crest of alveolar bone and get inserted in the cementum of neighboring tooth.

Function: They have the innate capacity to reconstruct themselves in periodontal disease even there is destruction of the alveolar bone. This unique property of fibers is responsible for returning teeth to their original state after orthodontic therapy.

2. Alveolar crest group (apico-oblique)

Location: Cervical root to alveolar crest of alveolar bone proper

Function: Prevent extrusion and lateral tooth movements

3. Horizontal group

Location: Mid root to adjacent bone proper

Function: Resists horizontal forces

4. Oblique group (coronal-oblique)

Location: Apical one-third of root to adjacent bone proper

Function: Resists vertical masticatory stresses and convert them into tension on alveolar bone

5. Apical group

Location: Apex of root to fundic proper

Function: Prevent tooth tipping, resist luxation and protect neurovascular supply to the tooth

6. Interradicular group

Location: Between roots to alveolar bone proper

Function: Prevent luxation, torquing and tooth tipping