Every cell of the organism has the same DNA sequence and same genes. However, not all genes are expressed in every single cell at the same time. Only those genes necessary for a specialised function of a specialised cell are expressed in the specialised cell. For example, skin cells have some different proteins than nerve cells. Genes responsible for those "skin proteins" are activated in skin cells and are turned off in nerve cells.
Atom refers to a tiny particle, which is the basic building block of all the substances and whose properties determine the characteristics of an element made up of only of those atoms.
All the living and nonliving matter in this world are made up of atoms and elements. Everything in the universe is matter, and matter comprises elements. Some of the elements are important to living things.
Elements are formed by atoms, and atoms comprise protons, electrons, and neutrons. The number of protons in an element's atom signifies the identity of the element.
Birds have great vision and can see throughout night and day
