Which of the following materials is not a living semi-permeable membrane?

Analyze the question: The question asks which material is not a living semi-permeable membrane. A living membrane comes from living tissue (plant or animal) and selectively allows some substances to pass through.

Explain the concept: Osmosis is the movement of water through a semi-permeable membrane from a region of high water potential (dilute solution) to a region of low water potential (concentrated solution).

Semi-permeable membranes fall into two groups:

• Living (biological) membranes: from living or once-living tissue, such as animal bladder, plant tissues, and the cell membrane.
• Non-living (artificial) membranes: made from non-biological material, such as cellophane (Visking tubing) and parchment paper.

Go through the options:

• A. Pig's bladder: animal tissue, so it is a biological membrane.
• B. Unripe pawpaw fruit: plant tissue, so it is biological.
• C. Yam tuber: plant tissue, commonly used in osmosis experiments, so it is biological.
• D. Sheet of cellophane: a synthetic material made from processed cellulose. It is semi-permeable but was never a living tissue, so it is not a living membrane.

Answer: The correct option is D. Sheet of cellophane.

Tip: In osmosis experiments, remember that cellophane and Visking tubing are the standard artificial membranes. When a question says "not living," look for the manufactured material. Pig's bladder, yam, and pawpaw all come from living organisms.