All four statement is right before blood transfusion blood and tissue matching, in 2nd statement. due to allergy Blood pressure decrease because histamine release more so if we use antihistamines, steroids and adrenaline then blood pressure increase and cure allergy, in 3rd statement pneumonia and common cold is spreadable disease it is droplets infection, 4rth statement normal cells have tendency for contact inhibition(reduce the extra growth of surrounding cells) but in cancer this property not possible

Tissue and blood matching before transplantation

- The statement (a) is true. Tissue matching and blood matching is indeed essential before transplantation.
- Tissue matching is done to ensure compatibility between the donor and recipient tissues. This is important to minimize the risk of rejection of the transplanted organ or tissue by the recipient's immune system.
- The human leukocyte antigens (HLAs) play a crucial role in tissue matching. The HLA system is a group of proteins present on the surface of cells that help the immune system distinguish between self and non-self. Matching the HLAs between the donor and recipient increases the chances of a successful transplant.
- Blood matching, on the other hand, involves matching the blood type between the donor and recipient. Blood types are classified based on the presence or absence of specific antigens on the surface of red blood cells. A mismatch in blood types can lead to severe complications, such as hemolytic reactions, which can be life-threatening.

Symptoms of allergy and their treatment

- The statement (b) is true. Symptoms of allergy can be rapidly decreased with the use of antihistamines, adrenaline, and steroids.
- Allergies are immune responses triggered by exposure to allergens, such as pollen, dust mites, or certain foods. They can cause symptoms like sneezing, itching, watery eyes, and skin rashes.
- Antihistamines are commonly used to relieve allergy symptoms. They work by blocking the action of histamine, a chemical released by the immune system during an allergic reaction.
- Adrenaline (epinephrine) is a hormone and medication that can be used in severe allergic reactions, known as anaphylaxis. It helps to reverse symptoms like difficulty breathing, swelling, and low blood pressure.
- Steroids, such as corticosteroids, can also be used to reduce inflammation and suppress immune responses in allergic reactions. They are often prescribed in cases of severe or chronic allergies.

Transmission of pneumonia and common cold

- The statement (c) is true. Pneumonia and the common cold can indeed be spread to a healthy person through droplets from an infected person by coughing and sneezing.
- Pneumonia is a respiratory infection that can be caused by various pathogens, including bacteria, viruses, and fungi. The common cold is primarily caused by viral infections, most commonly rhinoviruses.
- When an infected person coughs or sneezes, tiny respiratory droplets containing the pathogens can be released into the air. These droplets can be inhaled by nearby individuals, leading to the transmission of the infection.
- It is important to practice good respiratory hygiene, such as covering the mouth and nose with a tissue or elbow when coughing or sneezing, to reduce the spread of pneumonia and the common cold.

Tumor cells and contact inhibition

- The statement (d) is true. Tumor cells do not show contact inhibition.
- Contact inhibition refers to the phenomenon where normal cells stop dividing when they come into contact with other cells. This mechanism helps maintain tissue structure and prevents overgrowth.
- In contrast, tumor cells often lose contact inhibition and continue to divide even when they are in contact with other cells. This uncontrolled cell division is one of the hallmarks of cancer.
- The loss of contact inhibition allows tumor cells to form masses or