I know this isn't answering your question but i think you will find it useful to visit the link pasted below. i just visited it and it explains pretty much everything about this.
A. Migration (birds migraye to warmer climates during colder months)
Answer:
Astrocytes
Explanation:
Astrocytes are specialized glial cells found in the brain and spinal cord, they are responsible for maintaining the electrolytic composition of the cerebrospinal fluid, induce the formation of the blood-brain barrier and act as a support and guide for neurons during migration. They keep the ionic composition of the extracellular fluid of the central nervous system through the water channels, Aquaporin-4 (AQP4) and K channels, located in the pedicle processes of the astrocytes in the perivascular space, these cells exchange K and water in said perivascular medium away from the neurons. Astrocytes selectively edematize during hypotonic stress, while neurons do not.
Answer:
When the organism inherits a mutated gene creating new colored organisms into the population, this can increase diversity. As more organisms inherit the same mutation, the population will become more variated, which can increase the organisms abilities to survive and adapt in a changing environment, and also improve the biological fitness of individuals; resulting in allowing more organisms to reproduce successfully.
Explanation: