Explanation

• Iodine deficiency causes goiter, an enlargement of the thyroid gland.
• Iodine is essential for the production of thyroid hormones.
• Severe iodine deficiency during pregnancy or early childhood can impair brain development.

Last verified on 07-09-2026

Explanation

• Myopia (Nearsightedness) is an eye defect in which near objects are clear but distant objects appear blurred.
• It occurs when the image forms in front of the retina instead of on it.
• It is corrected by using a concave (diverging) lens.
• The concave lens helps to shift the image back onto the retina.

Last verified on 01-04-2026

Explanation

• Allergy is an abnormal immune response to harmless substances like dust or pollen.
• It occurs when the body reacts excessively to an allergen.
• This reaction involves the immune system producing antibodies.
• Thus, allergy is mainly due to an antigen–antibody reaction.

Last verified on 23-04-2026

Explanation

• Depression is classified as a psychological and medical mood disorder
• It disrupts normal work and social life.
• Low mood or ongoing sadness
• Loss of pleasure in hobbies.
• Changes in sleep or weight

Explanation

• An endemic disease is a disease that is constantly present in a specific population or geographic area.
• Examples:
• Malaria
• Chickenpox
• Dengue Fever

Additional information 

• Epidemic: A sudden, unexpected spike in cases within a specific community or region.
• Pandemic: An epidemic that has spread globally, covering multiple countries or continents.

Last updated by NA on 16-07-2026