The condition characterized by a lack of melanin in skin, hair, and eyes is: MCQ with Answer and Explanation

Explanation:
Calcitonin, secreted by the thyroid gland, reduces blood calcium by inhibiting osteoclast activity and promoting calcium deposition in bones. Parathyroid hormone raises calcium. Thyroxine regulates metabolism, insulin lowers blood glucose.

Explanation:
Typhoid fever is caused by Salmonella typhi, transmitted through contaminated food and water. Widal test is used for diagnosis. Cholera is Vibrio cholerae.

Explanation:
Carbohydrates are the body's primary and most readily available source of energy, broken down into glucose for immediate cellular use. Proteins are essential 'body-building' foods, providing amino acids necessary for the growth, repair, and maintenance of tissues, muscles, and enzymes. Fats are essential macronutrients; they provide concentrated energy, are crucial for cell membrane structure, aid in the absorption of fat-soluble vitamins, and provide essential fatty acids. Thus, statements 1 and 2 are correct.