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 typical bunk bed for a child's room features two twin mattresses. A twin mattress is 39 inches wide and 75 inches long. But a different type of twin mattress exist: a twin XL. The extra long variety has the same width, but an extra five inches of length at 80 inches long.