i) AIDS is a viral disease called Acquired Immuno Deficiency Syndrome.
ii)  It is caused by Human Immunodeficiency Virus (HIV).

(i) Cancer is an abnormal and uncontrolled division of cells that invade and destroy surrounding tissue forming a tumor or neoplasm (new growth).
 

(i) Diabetes mellitus is a chronic metabolic disorder.
(ii) It is characterized by increased blood glucose level due to insufficient, deficient or failure of insulin secretion.
(iii) This is the most common pancreatic endocrine disorder.

A person who is habituated to a drug due to its prolonged use is called drug addict. This is called drug addiction or drug abuse.

The treatment of cancer involves the following methods:
(i) Surgery: Tumours are removed by surgery to prevent further spread of cancer cells.
(ii) Radiation therapy: Tumour cells are irradiated by lethal does of radiation while protecting the surrounding normal cells.
(iii) Chemotherapy: It involves administration of anticancerous drugs which prevent cell division and are used to kill cancer cells.
(iv) Immunotherapy: Biological response modifiers like interferons are used to activate the immune system and help in destroying the tumors.

Symptoms: Diabetes mellitus is associated with several metabolic alterations. The most important symptoms are.
(i) Increased blood glucose level (Hyperglycemia)
(ii) Increased urine output (Polyuria) leading to dehydration.
(iii) Loss of water leads to thirst (Polydipsia) resulting in increased fluid intake.
(iv) Excessive glucose excreted in urine (Glycosuria).
(v) Excess hunger (Polyphagia) due to loss of glucose in urine.
(vi) Fatigue and loss of weight.

Behavioural Changes:
Adverse effects among adolescents are:
(i) Drop in academic performance, absence from school or college.
(ii) Lack of interest in personal hygiene, isolation, depression, fatigue and aggressive behaviour.
(iii) Deteriorating relationship with family and friends.
(iv) Change in food and sleeping habits.
(v) Fluctuation in body weight and appetite.

Insulin deficiency occurs due to destruction of \(\beta \)-cells of the pancreas.

Type-2 Non-Insulin Dependent diabetes mellitus.

Lung cancer, bronchitis and pulmonary tuberculosis, emphysema, Hypoxia, increased blood pressure, gastric and duodenal ulcers.