Answer the question on the basis of passage given below:

Living systems are made up of various complex biomolecules like carbohydrates, proteins, nucleic acids, lipids etc. Proteins and carbohydrates are essential constituents of our food. Carbohydrates are primarily produced by plants and form a very large group of naturally occurring organic compounds. SOme common examples are cane sugar, glucose, starch etc.

Which animal starch is found in yeast and fungi?

Glycogen

The correct answer is option 2. Glycogen.

Glycogen is a polysaccharide, which means it is a complex carbohydrate made up of many glucose molecules linked together. It serves as the primary storage form of glucose in animals, fungi, and some bacteria, including yeast. Glycogen is structurally similar to amylopectin, a component of plant starch, but with more frequent branching. The glucose units in glycogen are linked primarily by α(1→4) glycosidic bonds, with branches formed by α(1→6) glycosidic bonds approximately every 8-12 glucose units. Glycogen is stored in the liver and muscle tissues of animals and serves as a readily available energy reserve. In fungi and yeast, glycogen plays a similar role, providing a glucose reserve that can be quickly mobilized when energy is needed. The term "animal starch" is used to describe glycogen because it is the equivalent of starch (found in plants) in the animal kingdom. However, this term can be misleading because glycogen is not limited to animals—it is also found in fungi, including yeast.

Starch vs. Glycogen: While both starch (in plants) and glycogen (in animals and fungi) are polysaccharides used for energy storage, they differ in their structure and where they are stored:

Starch is composed of two types of molecules: amylose (linear) and amylopectin (branched).

Glycogen is more highly branched than amylopectin, making it more compact and allowing for rapid release of glucose when needed.

In yeast and fungi, glycogen serves as an essential energy storage molecule:

Yeast: Yeast cells, particularly during times when glucose is abundant, will store excess glucose as glycogen. When glucose is scarce, yeast can break down glycogen to release glucose, which is then used to generate energy via glycolysis.

Fungi: Similar to yeast, fungi store glycogen as an energy reserve. When conditions are unfavorable, such as during nutrient scarcity, fungi can break down glycogen to maintain energy production and cellular functions.

Comparison with Other Options
Let us briefly compare glycogen with the other options listed in the question:

Amyloprctin (Amylopectin): This is one of the two components of starch, found in plants, not in animals, yeast, or fungi. It is a branched polysaccharide but less branched than glycogen.

Lactose: This is a disaccharide composed of glucose and galactose. It is found in milk and dairy products and is not related to yeast or fungi.

Sucrose: Also known as table sugar, sucrose is a disaccharide made up of glucose and fructose. It is found in plants and is not related to the storage of energy in yeast or fungi.

Conclusion

Glycogen is the correct answer because it is the polysaccharide used by animals, fungi, and yeast for storing glucose. It functions similarly to starch in plants but is more highly branched, making it a more efficient storage molecule that can be quickly mobilized for energy when needed. The other options (amylopectin, lactose, and sucrose) are not involved in energy storage in yeast and fungi, making glycogen the appropriate choice.