1. What is a membrane?

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answers. Use the "Hint" button to get a free letter if an answer is giving you trouble. You can also click on the "[?]" button to get a clue. Note that you will lose points if you ask for hints or clues!
Membrane is any sheet that
separates region from another
or permitting (selectively
completely) the passage substances.

The skin, example, can be
a membrane that
the exterior from interior of the
; cellophane, used in
laboratories to separate , acts
as a too.