The term heteroecious means

Options

A. passing of the life cycle on two hosts by a pathogen
B. presence of heterothallism
C. presence of heterokaryons
D. all are wrong

Answer

### Step-by-Step Text Solution:

1. **Understanding the Term "Heteroecious":**
- The term "heteroecious" refers to organisms, particularly certain types of parasites, that require two different hosts to complete their life cycle.

2. **Differentiating Between Heteroecious and Autoecious:**
- Heteroecious organisms need two hosts: one host is used for the adult stage, and the other host is used for the juvenile or other stages of their life cycle.
- In contrast, "autoecious" organisms can complete their life cycle within a single host.

3. **Examples of Heteroecious Organisms:**
- Common examples of heteroecious organisms include certain types of rust fungi, such as *Puccinia* and *Gymnosporangium*. These fungi exhibit a life cycle that involves two different host plants.

4. **Analyzing the Options:**
- Option A states: "Passing of life cycle on to host biopathogen." This aligns with the definition of heteroecious organisms.
- Option B and C do not accurately reflect the meaning of heteroecious.
- Option D states "All are wrong," which is incorrect since option A is correct.

5. **Conclusion:**
- Based on the definitions and examples discussed, the correct answer to the question "The term heteroecious means" is option A: "Passing of life cycle on to host biopathogen."