Yes. If they let anything in or out, the organism would die fairly quickly.
Solid materials
Mass is in everything; gas, liquid and solid. Everything has some sort of weight, after all! You might be thinking of defined shape, which is a characteristic only solids have.
Liquid
Phagocytosis
yes
can be done by molecular sieving, membranes and the sorts
All known living things have cells. There are many non-living things that do not have cells.
It enters capillaries and is carried to all parts of the body. Then it passes through the cell membranes and is used for building and maintaining the health of the cells. it turnes into a brown solid or waste and then comes out the rectum
They make up structural parts of cell membranes
They make up structural parts of cell membranes
The atom is the basis of everything. Atoms themselves are made up of different particles, but particles are not 'solid stuff' and atoms are. Everything which we can see - unaided - in the universe, is made of atoms. Without "solid stuff" we would not be here to observe whatever universe might otherwise exist in a 'particle-only" universe.
Blood has red cells and white cells, but I'm not sure what is meant by 'solid part'.
There are no "solids" because they're all in solution; the closest you might come is the membranes of the various blood cells, and/or the (temporarily) unconnected fat molecules that are normally fastened to various transport proteins.
A solid ball of cells is called a morula. A morula is an embryo that is at an early stage of embryonic development.
Cells make up the solid portion which is 45% of the blood. red blood cells, hemoglobin, whiteblood cells, and platelets.
The solid portion of the blood is mainly made up of red blood cells. There are white blood cells and platelets too.
They make up structural parts of cell membranes