Answer:
a identification key
Explanation: because it identifys you
Lets consider the water drop as being part of the water in a lake. The water droplet evaporates and changes from a liquid state to a vapor state by gaining energy and travels up to the upper atmosphere. In the atmosphere the water droplet once again condenses in the clouds and is stored until it can be precipitated on to the land again in the form of rain or other forms of precipitation.
Answer:
Adaptive Immune System
Explanation:
The adaptive immune response consists of cellular immunity and humoral immunity. They both involve specialized cells for fighting off bacteria and viruses which is what the adaptive immune system is responsible for.
Answer:
Evolution in nature by natural selection only modifies the structures present in the ancestors and favors the better adapted structures.
Explanation:
An engineer can design the bones and muscles of the forelimbs of given organisms as per their needs and give rise to new unique structures for each of these organisms.
On the other hand, evolution in nature allows the modification of existing traits by the accumulation of variations. The adaptive variations in the traits are then favored by natural selection. Therefore, forelimbs of mammals such as horses, whales, and bats have evolved by modification of the forelimbs present in their common ancestors.
The limitation of modification of existing structures does not allow the formation of a completely new structure.
