Which of the following features distinguishes animals from organisms in other multicellular kingdoms?

• A. They perform photosynthesis using chloroplasts.
• B. They have cell walls made of chitin.
• C. They reproduce exclusively by producing spores.
• D. They lack cell walls and are heterotrophic by ingestion.

Answer: (D)

Verified step by step guidance

1. Understand the question: The problem asks for a distinguishing feature of animals compared to organisms in other multicellular kingdoms. This requires knowledge of the characteristics of animals and how they differ from plants, fungi, and other kingdoms.
2. Review the incorrect options: Animals do not perform photosynthesis using chloroplasts (a feature of plants), do not have cell walls made of chitin (a feature of fungi), and do not reproduce exclusively by producing spores (a feature of fungi and some plants).
3. Focus on the correct answer: Animals lack cell walls, which is a key difference from plants and fungi, both of which have cell walls. Additionally, animals are heterotrophic by ingestion, meaning they obtain nutrients by consuming other organisms, unlike plants that are autotrophic and fungi that are heterotrophic by absorption.
4. Clarify the concept of heterotrophy: Heterotrophic organisms rely on external sources of organic compounds for energy and nutrients. Animals ingest food, digest it internally, and absorb nutrients, which is distinct from fungi that absorb nutrients externally.
5. Summarize the distinguishing features: Animals are unique among multicellular kingdoms because they lack cell walls and are heterotrophic by ingestion. These features set them apart from plants, fungi, and other multicellular organisms.