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.
Twin Mattress. A twin mattress is the smallest possible mattress size, other than a crib-sized mattress. Twin mattress dimensions are approximately 38 inches wide by 75 inches long. Both twin and full sizes are approximately 75 inches long, which may be too short for some adults, especially men.