Final answer:
Structures composed of specialized tissues designed to perform specific functions in plants and animals are called organs.
Step-by-step explanation:
In both plants and animals, structures composed of specialized tissues designed to perform specific functions are called organs.
In animals, organs are made up of different types of tissues, such as epithelial, connective, muscle, and nervous tissues. Each tissue type has a specific role in carrying out the functions of the organ.
For example, in plants, the root, stem, and leaf are organs that are composed of different types of tissues, which work together to perform specific functions like absorption of water and nutrients, transportation of materials, and photosynthesis.