It is always said that atoms are the smallest particles of which the whole world is built. does this also apply to our body? Do (body) cells also consist of atoms?

Answer

To answer this question, let’s go from largest to smallest:

First you have a body made up of organs. Those organs are made up of tissue and tissue consists of cells. The cells contain all kinds of organelles (e.g. chloroplast, endoplasmic reticulum,…) and all kinds of substances that the cell needs such as: proteins, DNA…
Those things are in turn made up of molecules: e.g. proteins from amino acids
and amino acids are made up of atoms.
Atoms, in turn, are made up of electrons and the nucleus, which contains protons and neutrons…
You also have a whole host of small particles such as photons, neutrinos,…but I think you can remember that atoms are indeed the building blocks of all matter.