Reason: Lack of nutrients

Explanation:

When colonies of yeast fail to multiply in water but multiply in a sugar solution, the most likely reason is the lack of nutrients in water. Yeast requires certain nutrients to grow and multiply, and these nutrients are not present in plain water. However, when yeast is provided with a sugar solution, it receives the necessary nutrients to support its growth and multiplication.

Key Points:
- Water does not provide the necessary nutrients for yeast growth.
- Yeast requires specific nutrients to multiply.
- Sugar solution provides the necessary nutrients for yeast multiplication.
- The lack of nutrients in water inhibits yeast multiplication.
- Nutrients in the sugar solution enable yeast to grow and reproduce.

Importance of Nutrients:
Yeast is a single-celled organism that requires nutrients to carry out its metabolic processes and reproduce. These nutrients include carbon, nitrogen, phosphorus, and various vitamins. Without these essential nutrients, yeast cannot carry out its life processes or multiply.

Role of Sugar:
Sugar, such as glucose or sucrose, is a source of carbon and energy for yeast. When yeast is provided with a sugar solution, it can break down the sugar through a process called fermentation. This process generates energy and produces byproducts like carbon dioxide and alcohol. The breakdown of sugar provides the necessary nutrients for yeast to grow and multiply.

Water as a Medium:
While water is essential for life, it does not provide the necessary nutrients for yeast multiplication. Water alone lacks the carbon and energy sources required for yeast metabolism. Therefore, yeast colonies fail to multiply when placed in plain water.

Conclusion:
The reason why colonies of yeast fail to multiply in water but multiply in a sugar solution is the lack of nutrients in water. The sugar solution provides the necessary nutrients, including a carbon source, for yeast growth and multiplication.

Because in sugar solution yeast get both water and energy (sugar) at the same time wgich help in fast reproduction