| I: | Salmonella typhi is a pathogenic bacterium which causes typhoid fever in human beings. |
| II: | These pathogens generally enter the small intestine through food and water contaminated with them |
| III: | The pathogen remains confined to the small intestine. |
| IV: | Intestinal perforation and death may occur in severe cases. |
| V: | Typhoid fever could be confirmed by Widal test. |
| 1. | Streptococcus pneumoniae and Staphylococcus aureus |
| 2. | Haemophilus influenzae and Streptococcus pneumoniae |
| 3. | Pneumocystis carinii and Mycoplasma hominis |
| 4. | Streptococcus pyogenes and Bacillus anthracis |
| 1. | Rhino viruses cause the common cold. |
| 2. | Rhino viruses infect the nose and respiratory passage and frequently involve the lungs. |
| 3. | The common cold is characterised by nasal congestion and discharge, sore throat, hoarseness, cough, headache and tiredness. |
| 4. | It spreads though droplets and through contaminated objects. |
| I: | Sporozoites are the infectious form for humans. |
| II: | The parasites initially multiply within the red blood cells and then attack the liver cells. |
| III: | The rupture of RBCs is associated with release of a toxic substance, haemozoin, which is responsible for the chill and high fever recurring every three to four days. |
| IV: | Fertilization occurs in human RBCs |
| 1. | Droplet |
| 2. | Direct contact |
| 3. | Contaminated water, vegetables, fruits, etc. |
| 4. | Mosquito Vector |
| Assertion (A): | Any subsequent encounter with the same pathogen elicits a highly intensified secondary response of the acquired immune system in our body. |
| Reason (R): | Acquired immune response retains the memory of previous encounters with the antigens. |
| 1. | Both (A) and (R) are True and the (R) correctly explains (A). |
| 2. | (A) is True; (R) is False |
| 3. | (A) is False; (R) is True |
| 4. | Both (A) and (R) are True but the (R) does not correctly explain (A). |