Explanation:
One of a number of alternative forms of the same gene occupying a given position, or locus, on a chromosome is allele.
Ectopic focus or ectopic pacemaker happens when an excitable group of cells outside the normal sinoatrial node causes premature heartbeat. Sinoatrial node (SA node) is the pacemaker of the heart. Most people experience ectopic focus but persistent occurrence may need the client/patient to visit the doctor. If a client or patient complains of ectopic focus, it is better to consider his/her activity before visiting the clinic. Ask, for example if the client/patient had a vigorous exercise because it might be causing the irregular heartbeat, how often is he/she experiences such irregularity in his/her heartbeat (acute ectopic foci is usually non-life threatening, however, chronic type requires medical help), his/her lifestyle (he/she might be using illegal drugs, smokes and/or drinks alcohol,had too much coffee etc). Again, history taking is very vital.
I think this would be the environment. That's my guess
Frog RBCs contain a DNA-bearing nucleus that is visible in the center of the cell. Human RBCs do not possess nucleus along with other cell organelles such as mitochondria, Golgi apparatus and endoplasmic reticulum in order to accommodate greater amount of haemoglobin in the cells. Denucleation of rbcs is an adaptation, Which makes the mammalian red blood cell effective at transporting oxygen/eliminating CO2.
