Diseases like dysentery, cholera, typhoid, etc., are more common in over crowded human settlements. Why?
Dysentery, cholera and typhoid are more common in crowded settlements because these are infectious diseases and spread from person to person contact. Water gets contaminated with the excreta of infected people and causes the spread of infection to other people.
From which plant cannabiniods are obtained? Name any two cannabinoids. Which part of the body is effected by consuming these substances?
Cannabinoids are obtained from the inflorescence of the plant Cannabis sativa. Marijuana, hashish, charas, ganja are some cannabinoids. These chemicals interact with cannabinoid receptors of the body, mainly present in the brain. Cardiovascular system of the body is effected adversly by consuming these substances.
In the metropolitan cities of India, many children are suffering from allergy/asthma. What are the main causes of this problem. Give some symptoms of allergic reactions.
In metropolitan cities life style is responsible in lowering of immunity and sensitivity to allergens. More polluted environment like dust in surroundings increases the chances of allergy in children. Some symptoms of allergic reactions are sneezing, watery eyes, running nose and difficulty in breathing.
What is the basic principle of vaccination? How do vaccines prevent microbial infections? Name the organism from which hepatitis-B vaccine is produced.
The principle of vaccination is based on the property of 'memory' of immune system.
In vaccination, a preparation of antigenic proteins or inactivated/live but weakened pathogens is introduced into the body. The antigens generate primary immune response by producing antibodies along with memory B-cells and T-cells.
When the vaccinated person is attacked by the same pathogens, the existing memory B-cells and T-cells recognise the antigen and overwhelm the invaders with massive production of lymphocytes and antibodies.
Hepatitis-B vaccine is produced from yeast.
What is cancer? How is a cancer cell different from the normal cell? How do normal cells attain cancerous nature?
An abnormal and uncontrolled division of cells is termed as cancer. Genes called cellular oncogenes (c-onc) or proto-oncogens present in normal cells when activated under certain conditions lead oncogenic transformation of the normal cells leading cancer.
A cancer cell is different from the normal cell in following ways
| Cancer cell | Normal cell |
|---|---|
| Cancer cells divide in an uncontrolled manner. | Normal cells divide in a controlled manner. |
| The cells do not show contact inhibition. | The cells show contact inhibition. |
| Life span is indefinite. | Life span is definite. |