They are both comprised of cells. Their cells both have a nucleus and cell surface membrane.
the bark is the part of an oak tree that is most like a human skin
preventing entry of pathogens
The upper skin of the leaf has a layer of wax on it, called a cuticle. This makes the leaf waterproof. The upper skin of the leaf has a layer of wax on it, called a cuticle. This makes the leaf waterproof.
ytiger skin protects the tiger but human prints are just some prints of humanns.
The outer layer of a leaf's skin is called the waxy cuticle, or just cuticle. You could also include the next layer, the epidermis layer. Mostly, though, the leaf's skin is called the 'Leaf surface'.
they all have numbers
The common name for lemon leaf is lemon balm.
Leaf
if you are talking about the flag no it is not but if you are talking about the leaf then yes it is a leaf and it is common
Human skin is well skin, and polar bears aren't human skin.
cloroplasts
Both has epidermis and dermis. Under epidermis, stratum corneum and stratum germintivum are common sublayers.