Which statement about yeast is true?

• A. Yeast are single-celled fungi that ferment sugars and can grow with or without oxygen.
• B. Yeast are multicellular organisms that require sunlight to grow.
• C. Yeast do not ferment sugars.
• D. Yeast cannot grow in the presence of organic matter.

Answer: (A)

Yeast have a simple, energy-producing lifestyle: they are single-celled fungi that can ferment sugars and grow with or without oxygen. This means they don’t need light to live, unlike plants, and they can switch between using oxygen to generate energy or fermenting sugar when oxygen is limited. This dual capability is central to many food processes, from dough rising to alcohol production, and is why they’re described as fermenters that can thrive in both aerobic and anaerobic conditions.

The other statements don’t fit because yeast aren’t multicellular plants that need sunlight, they do ferment sugars (so claiming they don’t is incorrect), and they readily grow on organic matter rather than avoiding it.