In Marchantia and Riccia, Antheridia and Archegonia are produced on - and - thalli respectively.

Options

A. same, same
B. same, different
C. different, same
D. different, different

Answer

To solve the question regarding where Antheridia and Archegonia are produced in Marchantia and Riccia, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organisms:**
- Marchantia and Riccia are both types of bryophytes.
- Marchantia is known to be dioecious, meaning it has distinct male and female individuals.
- Riccia is monoecious, meaning it has both male and female reproductive structures on the same individual.

2. **Understand the Reproductive Structures:**
- Antheridia are the male sex organs that produce male gametes (sperm).
- Archegonia are the female sex organs that produce female gametes (eggs).

3. **Determine the Location of Reproductive Structures in Marchantia:**
- Since Marchantia is dioecious, Antheridia and Archegonia are produced on different thalli (plural of thallus).
- This means that one thallus will have Antheridia (male), and a different thallus will have Archegonia (female).

4. **Determine the Location of Reproductive Structures in Riccia:**
- Riccia, being monoecious, produces both Antheridia and Archegonia on the same thallus.
- This means that a single Riccia thallus will have both male and female reproductive structures.

5. **Conclusion:**
- Therefore, the answer to the question is:
- Antheridia are produced on different thalli in Marchantia.
- Archegonia are produced on the same thallus in Riccia.

### Final Answer:
- In Marchantia, Antheridia are produced on **different thalli**.
- In Riccia, Archegonia are produced on **the same thallus**.