Prokaryotes account for roughly half of terrestrial photosynthesis?

The statement is partially correct. Prokaryotes, specifically cyanobacteria, do contribute significantly to global photosynthesis. However, it's hard to quantify if they account for "roughly half" of terrestrial photosynthesis.

Here's a step-by-step breakdown:

1. Photosynthesis is the process by which green plants, algae, and some bacteria use sunlight to synthesize foods with the help of chlorophyll pigments. During this process, they absorb carbon dioxide and release oxygen.

2. Prokaryotes that perform photosynthesis are primarily cyanobacteria. They are believed to be among the first organisms to perform photosynthesis and have significantly contributed to the oxygenation of Earth's atmosphere.

3. Cyanobacteria are found in a wide range of habitats, including terrestrial, marine, and freshwater environments. They form a significant part of microbial mats in various ecosystems and can also form symbiotic relationships with plants, lichens, and fungi.

4. While cyanobacteria do contribute to global photosynthesis, it's challenging to quantify their exact contribution. Various factors, such as their population size, habitat, and photosynthetic efficiency, would need to be considered.

5. Most of the terrestrial photosynthesis is carried out by land plants, which have a larger biomass and higher photosynthetic efficiency compared to cyanobacteria.

6. Therefore, while prokaryotes (cyanobacteria) do contribute significantly to global photosynthesis, it might not be accurate to say they account for "roughly half" of terrestrial photosynthesis. More research would be needed to quantify their exact contribution.