Problem 83 - Objective Biology for NEET

Question

Which one of the following is not a polymeric substance? (a) Rubber (b) Morphine (c) Protein (d) Cellulose

Step-by-Step Solution

Answer

The substance that is not a polymeric substance is Morphine.

Step 1: Understanding Polymeric Substances

Identify what a polymeric substance means. A Polymer is a substance which is made up of a large number of similar units.

Step 2: Classifying each substance

Rubber is a polymer made up of isoprene units. Proteins are polymers of amino acids. Cellulose is a polymer made up of glucose units.

Step 3: Identifying the non-polymer

Morphine is an alkaloid from the opium poppy. It is a compound but not made up of repeating subunits, so it is not a polymer.

Key Concepts

Understanding Rubber as a Polymer

Rubber is a fascinating material known for its elasticity. Naturally found as latex from certain trees, rubber is a polymer largely composed of isoprene units. When processed, these units link together to form long chains. This gives rubber its stretchy, flexible properties.

• Each isoprene unit in natural rubber repeats to create a polymer chain, the more repeating units, the greater the flexibility.
• Its ability to return to its original shape after being stretched makes it invaluable for products like tires, elastic bands, and gloves.

Understanding the structure of rubber helps one appreciate its many practical applications. It showcases the power of polymers in everyday life.

Proteins: The Building Blocks of Life

Proteins are crucial for the functioning of living organisms. They are complex polymers made up of amino acid monomers. Each protein polymer can be incredibly long, made from 20 different amino acids arranged in countless ways.

• The sequence and structure of amino acids define the protein's specific properties and function.
• Examples include enzymes, hormones, and antibodies, each playing critical roles in biological systems.

Proteins are indispensable, and their polymeric nature allows them to form infinite combinations, vital to all life forms.

Cellulose: The Natural Polymer in Plants

Cellulose is another natural polymer, and it's a significant component of plant cell walls. Composed of glucose units, cellulose gives structural integrity to plants.

• The glucose monomers are linked by beta-1,4-glycosidic bonds, forming strong, linear chains.
• This structure makes cellulose rigid, which helps maintain plant rigidity and form.

Humans cannot digest cellulose; however, it serves as dietary fiber, essential for digestive health. It illustrates how polymers can vary greatly in their functions and benefits.

Why Morphine is Not a Polymer

Morphine is a well-known pain relief medication derived from the opium poppy. Unlike the other substances discussed, morphine is not a polymer. It is an alkaloid, a naturally occurring compound with complex structures but does not contain repeated monomeric units.

• Morphine molecules are single, non-repetitive units, unlike the chains found in polymers.
• Its structure lends itself to effective interaction with human body receptors, providing its pain-relieving properties.

Understanding morphine's nature helps us see why it lacks the characteristics seen in polymers like rubber, protein, and cellulose.