In terms of organisms, photosynthesis occurs in autotrophes that contain the green pigment chlorophyll. This would include the entire plant kingdom, half of the Protista (the algae), & half the Moneran Kingdom (the blue-green algae).
A standard twin mattress is 39 by 75 inches. A king is 76 by 80 inches. This means that a headboard for a king bed is going to be about 76 inches or wider, plenty wide enough to go along the length of a twin bed. Headboards are often slightly wider than the bed for which they are made.
A twin-size bed is designed for one person. The main size difference between a twin bed and a full bed, also known as a double bed, is the width. A full bed offers more space from side to side, but certain twin beds are longer for taller users. A regular twin-size bed is 39 inches wide and 75 inches long, and is made to accommodate one adult or child.