The function of a cell membrane is to protect the structures within the cell, give shape to the cell and support its structure.
Any trait which has a completely genetic basis with no environmental factors playing any role are traits that are inherited in a completely environmental fashion. There are some traits which are purely genetic and are therefore also determined only through genes. However, the majority of (phenotypical) traits are inherited and determined both by genes and environment.
Nematocysts: A capsule within specialized cells of certain coelenterates, such as jellyfish, containing a barbed, threadlike tube that delivers a paralyzing sting when propelled into attackers and prey. Also called stinging cell.