1641. Which of these is not a region of the spinal cord ?

A. Thoracic
B. Pelvic *
C. Lumbar
D. None of these

1642. The shape of the external ear is due to :

A. Elastic cartilage *
B. Fibrocartilage
C. Articular cartilage
D. None of these

1643. The external surface of the stomach is covered by :

A. Mucosa
B. Serosa *
C. Parietal peritoneum
D. None of these

1644. Which of the following is not a human organ system ?

A. Integumentary
B. Muscular
C. Epithelial *
D. None of these

1645. Which of the following does not depend on the depth of the aquatic environment in a predictable way?

A. Salinity *
B. Temperature
C. Penetration by sunlight
D. None of these

1646. The quantity of available nutrients __________ from the lower levels of the energy pyramids to the higher ones :

A. Increases
B. Decreases *
C. Remains stable
D. None of these

1647. Which of the following is not a major sub division of the biosphere ?

A. Hydrosphere
B. Stratosphere *
C. Lithosphere
D. None of these

1648. Vaccination is synonymous with __________ immunity :

A. Natural active
B. Artificial passive
C. Artificial active *
D. None of these

1649. When a partient’s immune system becomes reactive to a drug , this is an example of :

A. Super infection
B. Drug resistance
C. Allergy *
D. None of these

1650. What is the smallest unit of heredity ?

A. Chromosomes
B. Gene *
C. Nucleotides
D. None of these