The element that is a key component of the thyroid hormones T₃ and T₄ is: MCQ with Answer and Explanation

Explanation:
The joints between skull bones are immovable fibrous joints called sutures, where bones are tightly connected by dense connective tissue. Hinge joint (elbow, knee) allows movement in one plane. Ball and socket (shoulder, hip) allows multi-directional movement. Pivot joint (atlas-axis) allows rotational movement. Sutures fuse completely in old age.

Explanation:
Typhoid is caused by the bacterium Salmonella typhi, transmitted through contaminated food and water. Influenza (flu) is a viral disease, malaria is protozoan (Plasmodium), AIDS is viral (HIV). Common bacterial diseases include cholera, tuberculosis, diphtheria, tetanus. Typhoid fever is characterized by prolonged fever, headache, and rose spots on the skin. Widal test is used for diagnosis.

Explanation:
The neuron is the basic structural and functional unit of the nervous system, consisting of a cell body, dendrites, and an axon. It transmits electrical impulses.