The 'Bundle of His' and 'Purkinje fibers' are specialized structures found in the: MCQ with Answer and Explanation

Explanation:
Rheumatoid arthritis is an autoimmune disease where the immune system attacks the synovial membranes of joints, causing inflammation and joint damage. Tetanus is bacterial (Clostridium tetani), typhoid is bacterial (Salmonella typhi), malaria is protozoan (Plasmodium). Autoimmune diseases result from failure of self-recognition by immune cells. Other examples: type 1 diabetes, multiple sclerosis, lupus.

Explanation:
In primary succession on a bare, lifeless rock (xerosere), the pioneer species are usually lichens (a symbiotic association of fungi and algae or cyanobacteria). Lichens can survive in harsh, dry conditions and secrete acids that slowly weather the rock, contributing to soil formation. Once a thin layer of soil is formed, mosses can colonize, followed by herbs, grasses, shrubs, and eventually a climax forest community.

Explanation:
The adult vertebral column consists of 33 vertebrae (though some are fused: 5 sacral and 4 coccygeal). The femur (thigh bone) is the longest and strongest bone. The skull is composed of 22 bones (cranium and facial bones), some fused but the mandible is movable. The rib cage has 12 pairs of ribs. The stapes in the ear is the smallest bone.