The Question is from neet-botany , and it was created by the author D VINOD

Question

Which of the following statements are incorrect?
I. Left end of a polysaccharide is called non-reducing end while right end is called reducing end
II. Starch and glycogen are branched molecules
III. Starch and glycogen are the reserve food materials of plants and animals, respectively
IV. Starch can hold iodine molecules in its helical secondary structure but cellulose being non-helical, cannot hold iodine

D VINOD · Accepted Answer

## CORE INFORMATION
✓ **Answer**: A
## CONCEPT FRAMEWORK
	**Primary Concept**: Carbohydrate structure and properties
	**Related Topics**: Polysaccharides, reducing sugars, starch, glycogen, cellulose, iodine test
	**Prerequisites**: Basic knowledge of carbohydrate chemistry.
## SOLUTION PATHWAY
**Given Information**:
	Four statements about polysaccharides.
**Method & Steps**:
	1. Analyze each statement for correctness.
	2. Identify the incorrect statements.
	3. Match the incorrect statements with the given options.

## OPTION ANALYSIS
[A] ✓: **I and II**
	* **I is incorrect**: The reducing end of a polysaccharide is the end with a free anomeric carbon that can participate in redox reactions.  The non-reducing end is the end where the anomeric carbon is involved in a glycosidic bond. The position (left or right) is irrelevant and depends solely on how the structure is drawn.
	* **II is incorrect**: Starch has two components: amylose (linear) and amylopectin (branched). Glycogen is highly branched. While glycogen is exclusively branched, starch has both branched and linear components. Thus, it is incorrect to say *both* starch and glycogen are branched molecules.  
[B] :x:
	* **III is correct**: Starch is the primary storage polysaccharide in plants, and glycogen serves the same purpose in animals.
[C] :x:
	* **IV is correct**: Starch forms a helical structure that can trap iodine molecules, leading to a characteristic blue-black color. Cellulose has a linear structure with hydrogen bonds between chains, preventing helix formation and iodine binding.
[D] :x:
	* **III is correct**:  (Explained above)
	* **IV is correct**: (Explained above)
## LEARNING AIDS
	**Common Mistakes**:
		1. Confusing reducing and non-reducing ends of polysaccharides: Remember the free anomeric carbon determines the reducing end.
		2. Generalizing starch as only branched:  Recall that starch comprises both amylose (linear) and amylopectin (branched).
	**Quick Tips**:
		1. Iodine test:  A positive iodine test (blue-black color) indicates the presence of a helical polysaccharide like starch.
		2. Branching in polysaccharides: Glycogen is highly branched, while starch has both linear and branched components.

D VINOD · Answer

The correct Option is "I and II"

D VINOD · Answer

II and III

D VINOD · Answer

I and IV

D VINOD · Answer

III and IV

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