The productivity of the oceans is approximately ....the annual net primary productivity of the whole biosphere .

Options

A. half
B. one third
C. one fifth
D. one fourth

Answer

To solve the question regarding the productivity of the oceans in relation to the annual net primary productivity of the whole biosphere, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Primary Productivity**:
- Primary productivity refers to the rate at which autotrophic organisms (like plants and phytoplankton) produce organic matter (biomass) through photosynthesis.

**Hint**: Remember that primary productivity is a measure of how much energy is converted by photosynthetic and chemosynthetic autotrophs to organic substances.

2. **Comparison of Terrestrial and Marine Ecosystems**:
- Terrestrial ecosystems (like forests and grasslands) are known to have higher productivity than marine ecosystems due to the dense vegetation and variety of plant life.

**Hint**: Think about the types of plants found in terrestrial ecosystems versus those in marine ecosystems.

3. **Role of Marine Producers**:
- In marine ecosystems, the primary producers are mainly phytoplankton, including diatoms and dinoflagellates, as well as some algae. However, the density of these producers is lower compared to terrestrial plants.

**Hint**: Consider the types of organisms that are responsible for photosynthesis in the ocean.

4. **Area Coverage vs. Productivity**:
- Although oceans cover more than 70% of the Earth's surface, their contribution to the total primary productivity of the biosphere is limited.

**Hint**: Reflect on how area coverage does not always correlate with productivity.

5. **Estimating Ocean Productivity**:
- It is estimated that the oceans contribute approximately one-third (1/3) of the total annual net primary productivity of the entire biosphere.

**Hint**: Think about fractions and how they represent parts of a whole.

6. **Final Conclusion**:
- Based on the above analysis, we conclude that the productivity of the oceans is approximately one-third of the annual net primary productivity of the whole biosphere.

**Hint**: Remember to summarize your findings clearly to answer the question directly.

### Final Answer:
The productivity of the oceans is approximately **one-third (1/3)** of the annual net primary productivity of the whole biosphere.