Why is the bird's lung more efficient than a human?
a. the air in the bird's lung flows in both directions
b. the air in the bird's lung is mixed with dead air
c. the air in the bird's lung flows in one direction
c. the air in the bird's lung flows in a countercurrent direction

Option C.

Explanation:

The bird's lung are said as more efficient than a human or mammals.

The bird's are having small lungs with nine air sacs playing an important role in respiration.The air sacs allows a unidirectional flow of air inside the lungs while in human the air flow takes place in bidirectional. Unidirectional flow results in the flow of fresh air along with high oxygen content in bird's lung. So, there is more oxygen available to diffuse into the blood in bird lungs.

Hence, the correct option is C.

prophase: we can observe the chromosomes to coil up and condense. they become visible. nuclear membrane and envelope disintigrate.s

metaphase: chromosomes align at the center, the metaphase plate. spindle fibers attach to centromeres of the sister chromatids. they meet at kinetochores.

anaphase: sister chromatids are pulled towards each opposing centromere, set on different poles.

telophase: chromosomes are now clustered up only on either sides of the cell. nuclear membranes reform, and a new cell wall forms along the cell plate. this will lead to cytokinesis, the process that divides the cell membrane and forms the cell wall.

some fungi obtain their nutrients from a living host (plant or animal) and are called most biotrophic fungi have fairly narrow host ranges—they are specialized on a limited called rhizomorphs that allow the fungus to grow from one tree to another. ascospores are formed inside a sac-like structure called an ascus. so your answer is a