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How does a plant move its leaves in response to touch?
By changing the amount of nucleic acid in them
By changing the amount of protein in them
By changing the amount of lipid in them
By changing the amount of water in them
By changing the amount of water in them
Plants like 'Mimosa pudica' (Touch-me-not) exhibit thigmonasty, a form of nastic movement, by changing the turgor pressure in specialized cells. This rapid response is due to the loss of water from the cells in the pulvinus, causing the leaves to fold or droop.
Plants like 'Mimosa pudica' (Touch-me-not) exhibit thigmonasty, a form of nastic movement, by changing the turgor pressure in specialized cells. This rapid response is due to the loss of water from the cells in the pulvinus, causing the leaves to fold or droop.
Think of it like a water balloon; if you suddenly let the water out, the balloon loses its shape and sags, just as the plant leaf sags when turgor pressure drops.
Turgor-Drop: Touch leads to Turgor, Turgor leads to Tumble.
╬иwтАЛ=╬иsтАЛ+╬иpтАЛ тАФ The water potential equation where ╬иpтАЛ (pressure potential) decreases during the leaf movement.
When the leaves are touched, an electrical impulse is generated, which triggers the release of chemical messengers. These signals cause the cells in the pulvinus (a swollen joint at the base of the leaf) to lose water through osmosis. As the water moves out of the vacuoles into the intercellular spaces, the cells lose their turgor pressure, become flaccid, and the leaf collapses.
The movement is non-directional, meaning it is a nastic movement, not a tropic movement.
The specialized cells involved in this movement are located at the base of the leaf called the pulvinus.
This is a rapid, reversible response to mechanical stimulation.
Protects the plant from herbivores by making it appear less appetizing or damaged upon contact.
Mimosa pudica (Touch-me-not plant)
Venus flytrap leaf closure mechanism (modified version of turgor-based movement)
Nucleic acid, protein, and lipid changes are structural or long-term growth processes, not involved in rapid touch-responsive movements.
Option D is the only one describing a rapid physiological change mediated by water flux.
D is correct тАФ The plant moves its leaves in response to touch by rapidly changing the water content (turgor pressure) in the cells of the pulvinus.
Always differentiate between 'tropic' movements (growth-dependent, directional) and 'nastic' movements (turgor-dependent, non-directional) for biology exam questions.
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