Crop milk is a secretion from the lining of the crop of parent birds that is regurgitated to young birds. They are found among all pigeons and doves where they are referred to as pigeon milk. Crop milk is also produced by flamingos and some penguins. Crop milk bears little resemblance to mammalian milk, being a semi-solid substance somewhat like pale yellow cottage cheese.

Correct Option: B

Crop milk is a secretion from the lining of the crop of parent birds that is regurgitated to young birds. They are found among all pigeons and doves where they are referred to as pigeon milk. Crop milk is also produced by flamingos and some penguins. Crop milk bears little resemblance to mammalian milk, being a semi-solid substance somewhat like pale yellow cottage cheese.

Pernicious anemia is one of many types of the larger family of megaloblastic anemias. It is caused by loss of gastric parietal cells which are responsible, in part, for the secretion of intrinsic factor, a protein essential for subsequent absorption of vitamin B₁₂ in the ileum.

Correct Option: B

Pernicious anemia is one of many types of the larger family of megaloblastic anemias. It is caused by loss of gastric parietal cells which are responsible, in part, for the secretion of intrinsic factor, a protein essential for subsequent absorption of vitamin B₁₂ in the ileum.

Quinine, as a component of the bark of the cinchona tree, was used to treat malaria from as early as the 1600s. The bark of trees in this genus is the source of a variety of alkaloids, the most familiar of which is quinine, an antipyretic (anti-fever) agent.

Correct Option: C

Quinine, as a component of the bark of the cinchona tree, was used to treat malaria from as early as the 1600s. The bark of trees in this genus is the source of a variety of alkaloids, the most familiar of which is quinine, an antipyretic (anti-fever) agent.

The Passenger Pigeon or Wild Pigeon is an extinct North American bird. The species lived in enormous migratory flocks until the early 20th century, when hunting and habitat destruction led to its demise.

Correct Option: A

The Passenger Pigeon or Wild Pigeon is an extinct North American bird. The species lived in enormous migratory flocks until the early 20th century, when hunting and habitat destruction led to its demise.

A humming bird can rotate each of its wings in a circle, allowing them to be the only bird which can fly forwards, backwards, up, down, sideways or sit in sheer space. To hover, hummingbirds move their wings forward and backward in a repeated figure eight, much like the arms of a swimmer treading water. Humming birds can move instantaneously in any direction, start from its perch at full speed, and doesn't necessarily slow up to land.

Correct Option: D

A humming bird can rotate each of its wings in a circle, allowing them to be the only bird which can fly forwards, backwards, up, down, sideways or sit in sheer space. To hover, hummingbirds move their wings forward and backward in a repeated figure eight, much like the arms of a swimmer treading water. Humming birds can move instantaneously in any direction, start from its perch at full speed, and doesn't necessarily slow up to land.