Chapter 20, Problem 19A

Summary Introduction

Introduction :

Fungi are among the oldest and the largest group of organism on earth. All fungi are either unicellular or multicellular eukaryotic heterotrophs. Fungi have a cell wall composed of chitin. There are about 100,000 identified species of fungi.

Answer to Problem 19A

Correct answer :

The correct answer is option (B) yeast.

Explanation of Solution

Explanation/justification for the correct answer :

Option (B) yeast. The single-celled or unicellular fungi are called yeast. They are found throughout the world in a variety of environment. There are hundreds of different kinds of yeast, the most familiar ones are used in the preparation of breads, beer and wine. Yeast is a single-celled fungi. So, the correct answer is option (B).

Explanation for incorrect answer :

Option (A) bread molds. Most members of Kingdom Fungi are multicellular. The structural units that make up the body of multicellular fungi are known as hyphae. Hyphae grow at their tips and branch to form a netlike mass called a mycelium. Bread molds are multicellular fungi that grow on bread. Bread molds reproduce by forming spores. The bread provides the nutrients for the spores to grow and multiply. So, this is an incorrect option.

Option (C) mushroom. Most members of Kingdom Fungi are multicellular. The structural units that make up the body of multicellular fungi are known as hyphae. Hyphae grow at their tips and branch to form a netlike mass called a mycelium. The mycelium is packed very tightly in mushrooms. Mushrooms are the fleshy reproductive structures known as fruiting body of the fungus found above the ground. The hyphae form all parts of the mushroom. So, this is an incorrect answer.

Option (D) Bird’s nest fungus. Most members of Kingdom Fungi are multicellular. The structural units that make up the body of multicellular fungi are known as hyphae. Hyphae grow at their tips and branch to form a netlike mass called a mycelium. Bird’s nest fungus is a saprophytic multicellular fungus with a cup like fruiting body. They grow on dead organic matter. Hence, this is an incorrect answer.