In passive transport, substances simply move from an area of higher concentration to an area of lower concentration, which does not require the input of energy. Concentration gradient, size of the particles that are diffusing, and temperature of the system affect the rate of diffusion
Answer:
retroviruses
segmented viruses
Explanation:
A retrovirus is a type of RNA virus that inserts a copy of its genome into the DNA of a host cell that it invades resulting in changing the original genome of that cell. There are about three examples of retroviruses, they are
* HIV
* Human T-lymphotropic virus type 1 (HTLV-1)
* Human T-lymphotropic virus type 2 (HTLV-II)
It should be understood that there is a difference between virus and retrovirus. This is that a retrovirus inserts its genome into the host's genome unlike the virus.
Segmented viruses are viruses that package all of their genome segments into a single particle.
In this case, these viruses have high rate rate of genetic mutation and adaptation.
Answer:
He meant that the supporting cells form a insulating coat on the nerve fibre called myelin seath. The myelin Sheath act similar to the rubber coating of household wiring because it electrically insulates the nerve fibre and speeds of conduction of nerve impulse..
Explanation:
- The supporting cells of the nervous system are together called neuroglia or glial cells.
- Unlike neurons these cells can divide in the mature nervous system and do not conduct nerve impulse.
- Out of six types of glial cells, four are located in the central nervous system (CNS) and they are;astrocytes, oligodendrocytes, ependymal cells and microglia.
- The remaining two types are the part of Peripheral nervous system (PNS) and include Schwann cells and Sattelite cells.
- Among these , the oligodendrocytes of the CNS and Schwann cells of the PNS forms myelin sheath on the axons of the nerve cell that act similar to the rubber coating on the household wiring.
- The myelin sheath electrically insulates the axon of a neuron and increase the speed of conduction of nerve impulse.
Though most prokaryotes have both a cell membrane and a cell wall, there are exceptions such as Mycoplasma (bacteria) and Thermoplasma ( archaea ) which only possess the cell membrane layer. The envelope gives rigidity to the cell and separates the interior of the cell from its environment, serving as a protective filter. Hope this helped!
