Concept:
Yeast reproduces asexually mainly by budding under favorable conditions.
Step 1: Analyze Statement I.
Budding is the most common method of asexual reproduction in yeast.
Thus, Statement I is correct.
Step 2: Analyze Statement II.
In yeast:
• Budding occurs under favorable conditions
• Under unfavorable conditions, yeast may form spores (sexual reproduction)
Thus, Statement II is incorrect.
Step 3: Conclusion.
\[
\text{Statement I is correct, Statement II is incorrect}
\]