Answer:
Myelination
Explanation:
The covering of myelin around the axons is called the myelin sheath. This myelin sheath helps in transfer of information faster and also in complex processes of the brain. The process of myelination begins in the PNS (peripheral nervous system).
The myelinated section are seperated from each other with a gap called nodes of ranvier. Glial cells (oligodendrocytes) forms the myelin sheath in the central nervous system and schwann cells (glial cells) forms the myelin sheath in peripheral nervous system. The propagation of electrical impulse in the myelinated fibers is by saltatory conduction that is from one node to another.
Answer:

Explanation:
Given -
Total Population - 
Individuals with homozygous HbA/hbA genotype - 
Individuals with homozygous hbs/hbs genotype -
Individuals with heterozygous hba/hbs genotype - 
Let us assume the given population is in Hardy Weinberg' equilibrium
The frequency of individuals in the given population with homozygous HbA/hba genotype is equal to number of individuals with homozygous HbA/hba genotype divided by total population.

The frequency of hba allele is equal to

Fossils are the remains or impression of the dead animals and plants that lived in the past.