Classification logic: What is the correct relationship between “fungi” and “heterotrophic organisms” when considering how these groups are defined biologically?

Introduction / Context:
Understanding set relationships prevents logical fallacies in biology. “Fungi” is a specific kingdom; “heterotrophs” describes a nutritional mode found in many kingdoms.

Given Data / Assumptions:

• Fungi are heterotrophic, absorbing organic nutrients.
• Heterotrophy also occurs in animals, many protists, and some bacteria.
• Therefore, the set of heterotrophs is broader than the set of fungi.

Concept / Approach:
Set inclusion: Fungi ⊂ Heterotrophs, while Heterotrophs ⊄ Fungi. This captures the correct one-way inclusion and excludes equivalence or reverse inclusion.

Step-by-Step Solution:
Define fungi by kingdom and heterotrophy by nutrition. List other heterotrophs (animals, protozoa, many bacteria). Conclude fungi are a subset of heterotrophs, not vice versa. Choose the statement expressing “all fungi are heterotrophs, but not all heterotrophs are fungi.”

Verification / Alternative check:
Examples: humans (heterotrophs) are animals, not fungi; yeasts are fungi and heterotrophs.

Why Other Options Are Wrong:

• Reverse inclusion or equality: Contradicts observed diversity of heterotrophy across kingdoms.
• Heterotrophs are plants: Plants are primarily photoautotrophs.

Common Pitfalls:
Equating nutritional modes with taxonomic ranks.

Final Answer:
All members of fungi are also members of heterotrophic organisms, but not all heterotrophs are fungi.