Heart attack is the death of a segment of heart muscle caused by the loss of blood supply. It occurs when the blood flow that brings oxygen to the heart muscle is severely reduced or cut off completely. The blood supply is usually lost because a coronary artery, one that supplies blood to the heart muscle, is blocked by a blood clot (coronary thrombosis).

Correct Option: C

Heart attack is the death of a segment of heart muscle caused by the loss of blood supply. It occurs when the blood flow that brings oxygen to the heart muscle is severely reduced or cut off completely. The blood supply is usually lost because a coronary artery, one that supplies blood to the heart muscle, is blocked by a blood clot (coronary thrombosis).

Individuals with type O blood are often called universal donors. They can receive blood only from a group O individual, but can donate blood to individuals of any ABO blood group (i.e., A, B, O or AB).

Correct Option: D

Individuals with type O blood are often called universal donors. They can receive blood only from a group O individual, but can donate blood to individuals of any ABO blood group (i.e., A, B, O or AB).

Chloramines are a group of chemical compounds that contain chlorine and ammonia. It is used as a disinfectant for water. The particular type of chloramine used in drinking water disinfection is called monochloramine. Chloramine is chiefly a secondary disinfectant that are added to water that has already been disinfected with a primary disinfectant, often chlorine.

Correct Option: C

Chloramines are a group of chemical compounds that contain chlorine and ammonia. It is used as a disinfectant for water. The particular type of chloramine used in drinking water disinfection is called monochloramine. Chloramine is chiefly a secondary disinfectant that are added to water that has already been disinfected with a primary disinfectant, often chlorine.

Children who receive very little sunshine (source of vitamin D) suffer from rickets, a skeletal disorder that results from a lack of vitamin D. Rickets is most common in children who are between 6 and 36 months old. Rickets has mostly disappeared in developed countries due to the introduction of fortified foods, such as cereals with added vitamin D.

Correct Option: A

Children who receive very little sunshine (source of vitamin D) suffer from rickets, a skeletal disorder that results from a lack of vitamin D. Rickets is most common in children who are between 6 and 36 months old. Rickets has mostly disappeared in developed countries due to the introduction of fortified foods, such as cereals with added vitamin D.

Nitrogen-fixing bacteria are microorganisms capable of transforming atmospheric nitrogen into fixed nitrogen. Rhizobium is one such bacteria that is associated with leguminous plants (e.g., various members of the pea family). It invades the root hairs of host plants and convert free nitrogen to ammonia, which the host plant utilizes for its development.

Correct Option: A

Nitrogen-fixing bacteria are microorganisms capable of transforming atmospheric nitrogen into fixed nitrogen. Rhizobium is one such bacteria that is associated with leguminous plants (e.g., various members of the pea family). It invades the root hairs of host plants and convert free nitrogen to ammonia, which the host plant utilizes for its development.