About 90 percent of total photosynthesis in the world is caused by :-

Options

A. Bryophytes
B. Algae
C. Pteridophytes
D. Angiosperms

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which organism is responsible for about 90% of the total photosynthesis occurring on Earth.

2. **Analyzing the Options**: The options given are Bryophytes, Algae, Pteridophytes, and Angiosperms. We need to evaluate which of these groups is most likely to account for the majority of photosynthesis.

3. **Evaluating Bryophytes**: Bryophytes, such as mosses and liverworts, are primarily terrestrial and have limited habitats. They do not contribute significantly to global photosynthesis due to their restricted distribution and lower biomass.

4. **Evaluating Pteridophytes**: Pteridophytes, which include ferns, also have a limited habitat compared to aquatic organisms. They are not as widespread as algae and do not dominate photosynthesis on a global scale.

5. **Evaluating Angiosperms**: Angiosperms (flowering plants) are significant contributors to photosynthesis, especially in terrestrial ecosystems. However, they are not as abundant in aquatic environments where a large portion of photosynthesis occurs.

6. **Evaluating Algae**: Algae, particularly phytoplankton, are found in vast quantities in oceans, lakes, and rivers. They are highly diverse, with many species capable of photosynthesis. Algae can thrive in various environments, including extreme conditions, making them highly resilient and widespread.

7. **Conclusion**: Given the abundance, diversity, and adaptability of algae, it is concluded that they are responsible for about 90% of the total photosynthesis on Earth. Therefore, the correct answer is **Algae**.

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