Explanation: In an incompatible blood transfusion, the antibodies in the recipient’s plasma bind to the antigens on the donor’s RBCs. This causes the red blood cells to agglutinate (clump together) and eventually undergo hemolysis (bursting). The released hemoglobin can block kidney tubules and cause kidney failure, which can be fatal if untreated. This is why blood group compatibility testing (cross-matching) is essential before transfusions.

Example:

If a person with blood group B (having anti-A antibodies) receives blood from a person with group A (which has A antigens), the recipient’s anti-A antibodies will attack the donor’s RBCs, leading to agglutination.

Explanation: Dehydration happens when the body loses excessive water through sweating, vomiting, diarrhea, or inadequate fluid intake. It disturbs the balance of electrolytes and reduces blood volume, leading to symptoms such as thirst, dry mouth, fatigue, and dizziness. To prevent dehydration, oral rehydration solutions (ORS) or adequate water intake are essential.

Explanation: Leguminous crops such as peas, beans, gram, and clover have a symbiotic relationship with Rhizobium bacteria in their root nodules. These bacteria convert atmospheric nitrogen into ammonia, enriching soil fertility naturally. Hence, legumes are used in crop rotation to restore nitrogen content in soil.

Diseases like Polio and Chicken Pox are caused by viruses. The Polio virus attacks the nervous system and can lead to paralysis, while the Varicella-zoster virus causes Chicken Pox, characterized by itchy blisters and fever. Viruses are acellular infectious agents that can reproduce only inside the living cells of a host organism.

Other options (for context)

• Bacteria: Cause diseases like tuberculosis, cholera, and typhoid, not polio or chicken pox.
• Protozoa: Cause diseases such as malaria and amoebiasis.
• Algae: Generally non-pathogenic; they do not cause human diseases like polio or chicken pox.

Explanation: The liver is the largest gland in the human body. It is located in the upper right part of the abdomen, just below the diaphragm. The liver performs multiple vital functions, including the secretion of bile (which helps in digestion of fats), detoxification of harmful substances, storage of glycogen (energy reserve), and the synthesis of proteins and cholesterol. It also plays a crucial role in regulating blood sugar levels and metabolism. The average adult human liver weighs about 1.2 to 1.5 kilograms.

Explanation: Acids do not turn red litmus to blue; they turn blue litmus paper red. Acids are sour in taste, corrosive in nature, and have a pH value less than 7. The statement that acids turn red litmus to blue is incorrect.

Explanation: In a parallel connection of resistances, the potential difference (voltage) across each resistor remains the same, while the current divides among the different branches according to their resistances. This property makes parallel circuits widely used in household electrical wiring.

Explanation: Fire extinguishers commonly used in houses and offices contain water, potassium bicarbonate (KHCO₃), and fluorocarbons. These chemicals help in extinguishing fires by cooling, cutting off oxygen supply, and preventing the spread of flames without leaving harmful residues.