Question

Sleep movements in Samanea saman are regulated by
A. Nitrogen
B. Phosphorus
C. Potassium
D. Magnesium

Answer 1

Hint: Sleep movement, or Nyctinasty, in reaction to darkness, to the nastic movement of leaves or petals of higher plants. For example, a biological rhythmic event is the closing of a flower at dusk. The sleeping motion of the legume leaves throughout the night is another. Nyctinasty is a distinct movement from a tropical one.

Complete answer:
Samanea saman is an elegant, large, spreading deciduous tree with a short, thick, dome-shaped crown; with occasional specimens up to 60 metres, it typically grows up to 30 metres tall. It has a small, generally crooked bole that can have a diameter of up to 200 cm. Trees in humid climates can be evergreen. It is also cultivated for its many applications, being a multipurpose tree. It is especially valued for its wood, but it also provides fruit, medicine and gum. It is one of the most widely planted tropical avenue and park trees, and is also commonly cultivated for other crops as a shade tree.
Nyctinasty is caused by changes of motor cells in asymmetrical volume. The alternative swelling and shrinking of motor cells at the base of the leaf induces nyctinastic motion. In turn, this is facilitated by changing osmotic pressures through anion and potassium ion channels caused by ion flow. Inside S. Saman, the movement of nyctinastic leaves is caused by the specialised motor organs, pulvini, at the base of the leaves or leaflets of the compound.
So, the correct answer is “Option C”.

Note:
The opening and closing of the circadian leaf of Fabaceae has been attracting the attention of scientists since Charles Darwin’s period. Movement of nyctinastic leaves of S. Saman under continuous light conditions was observed. In Japan, few studies have been carried out in order to learn more about it.