<span>Alleles are two different forms of single gene that are located in specific position on a specific chromosome. It can be classified into two allele pairs: homozygous and heterozygous. In homozygous, both alleles are the same whether they are both dominant or recessive; while in heterozygous, one allele is dominant and the other is recessive.</span>
Descending tracts are the pathways by which motor
signals are pass through from the brain to lower motor neurones. Thus, all
the neurones within the descending motor system are classed as upper motor
neurones. The lower motor neurones then directly innervate muscles to produce
movement. Their cell bodies are found in the cerebral cortex or the brain stem,
with their axons remaining within the CNS.
b)1 unicellular- means one cell
In the first stages of Alzheimer’s disease, the patient
affected may experience symptoms, such as memory loss of certain events. As the
time passes, the patient may experience long-term memory loses, the patient may
also revert into being a child. Patients who has been diagnose with Alzheimer’s
Disease are commonly diagnosis with pneumonia, which may lead to their death.
