The non-directional movement of a plant part in response to the touch of an object is called thigmonasty. In other words, thigmonasty is the nastic movement of a plant part in response to touch. Thus, the stimulus in thigmonasty is the 'touch'. An example of the nastic movement in plants caused by touch (or thigmonasty) is provided by the sensitive plant (Mimosa pudica) which is also known as touch-me-not plant. It is called chhui - mui in Hindi. If we touch the leaves (or rather leaflets) of the sensitive plant with our fingers, then its leaves fold up and droop almost immediately. The folding up of the leaves of sensitive plant on touching, is an example of nastic movements in plants (in which the stimulus is the 'touch' of our fingers).
1. The non-directional movement of a plant part in response to the touch of an object is called ______.
(i) Thigmonasty
(ii) Photonasty
2. State true or false. The sensitive plant has pad-like swellings called 'pulvini' at the base of each leaf.
(i) TRUE
(ii) FALSE
3. The folding up of the leaves of a sensitive plant on touching is due to the sudden loss of water from pad-like swellings called 'pulvini' present at the base of all leaves of the sensitive plant which make the pulvini lose their firmness causing the leaves to droop and fall. State true or false.
(i) TRUE
(ii) FALSE
4. State true or false. All the pulvini lose firmness and become limp due to which all the leaves above them collapse and fold up.
(i) TRUE
(ii) FALSE
5. The pulvini have ______ intercellular spaces (empty spaces) between their cells.
(i) Small
(ii) Large
