Which of the following is INCORRECT? The prothallus of a fern
A. Is flattened heart-shaped structure
B. Is green because its cells contain chloroplasts
C. Is the dominant plant
D. Bears the sexual organ
Correct Answer:C
Explanation
The correct answer is C. Is the dominant plant.
Detailed Explanation:
Understanding the Prothallus:
The prothallus is the gametophyte stage of ferns, which is a small, flat, heart-shaped structure that is typically green due to the presence of chloroplasts. It is important to note that the prothallus is not the dominant stage in the life cycle of ferns; rather, the sporophyte (the larger, leafy fern plant) is the dominant stage.
Why Option C is Correct:
In the life cycle of ferns, there are two main stages: the sporophyte and the gametophyte. The sporophyte is the dominant stage, which means it is the larger, more complex, and longer-lived part of the life cycle. The prothallus, being the gametophyte, is small, short-lived, and dependent on the sporophyte for nutrients and support. Therefore, stating that the prothallus is the dominant plant is incorrect.
Why the Other Options are Incorrect or Weaker:
Option A: Is a flattened heart-shaped structure:
This statement is correct. The prothallus is indeed a flattened, heart-shaped structure that is typically green. This shape allows for efficient light capture for photosynthesis.
Option B: Is green because its cells contain chloroplasts:
This statement is also correct. The prothallus contains chloroplasts, which are the organelles responsible for photosynthesis. This allows the prothallus to produce its own food and be green in color.
Option D: Bears the sexual organ:
This statement is correct as well. The prothallus bears the reproductive organs: the antheridia (male organs) and archegonia (female organs). These structures are essential for sexual reproduction in ferns, allowing for the production of gametes.
Summary of Key Points:
The prothallus is the gametophyte stage of ferns, not the dominant stage.
The dominant stage in the fern life cycle is the sporophyte, which is the larger fern plant.
The prothallus is a small, green, heart-shaped structure that contains chloroplasts for photosynthesis.
It bears the sexual organs necessary for reproduction, making it an important part of the fern's life cycle, but not the dominant form.
Revision Summary:
The prothallus is the gametophyte stage of ferns, not the dominant plant.
The dominant stage in ferns is the sporophyte.
The prothallus is green due to chloroplasts and is heart-shaped.
It contains reproductive organs for sexual reproduction.