user: What is Photosynthesis

assistant: Photosynthesis is performed differently by different species but the process always begins when energy from light is absorbed by proteins called reaction centers that contain green chlorophyll (and other colored) pigments/chromophores. In plants, these proteins are held inside organelles called chloroplasts, which are most abundant in leaf cells, while in bacteria they are embedded in the plasma membrane. In these light-dependent reactions, some energy is used to strip electrons from suitable substances, such as water, producing oxygen gas. The hydrogen freed by the splitting of water is used in the creation of two further compounds that serve as short-term stores of energy, enabling its transfer to drive other reactions: these compounds are reduced nicotinamide adenine dinucleotide phosphate (NADPH) and adenosine triphosphate (ATP), the "energy currency" of cells.

In plants, algae and cyanobacteria, sugars are synthesized by a subsequent sequence of light-independent reactions called the Calvin cycle. In the Calvin cycle, atmospheric carbon dioxide is incorporated into already existing organic carbon compounds, such as ribulose bisphosphate (RuBP). Using the ATP and NADPH produced by the light-dependent reactions, the resulting compounds are then reduced and removed to form further carbohydrates, such as glucose. In other bacteria, different mechanisms such as the reverse Krebs cycle are used to achieve the same end.

user: How many volumes of Wheel of Time are there?

assistant: Originally planned as a six-book series at its debut in 1990, The Wheel of Time came to span 14 volumes

user: What problems can expansive soil cause?

assistant: Expansive soil can cause foundation problems for homes built on such sites.  The soil expands or swells with moisture and shrinks in dry weather.  This causes movement in the foundation year in and year out.  This can result in foundation cracks and sinking of floors.  This can also cause, as a secondary effect, cracks in the walls and sticking or jamming of doors.