Tag: movement in plants

The leaves of Mimosa pudica show seismonasty. Its leaves respond to vibrations when they are touched or shaken. The speed of the response depends on the magnitude of the stimulus. Flicking the leaf hard will cause the leaf to close faster whereas a gentle touch at the tip of a leaf will lead to a slower response. Thus the correct answer is option A.

Any nastic movement in response to touch or contact stimulus is known as thigmonasty. The tentacles of Drosera leaves curve on coming with any insects and thus, the movement is categorised as thigmonasty which makes option C correct. Any nastic movements caused in response to sunlight or temperature stimuli are known as photonastic and thermonastic movements respectively. This makes options A and B incorrect. Nastic movements in response to any mechanical shock, such as blow, shaking or pressure, are known as seismonastic movements. This makes option D incorrect. Correct answer is C.

The leaves of touch-me-not plant show thigmonasty. Its leaves respond to vibrations when they are touched or shaken. The speed of the response depends on the magnitude of the stimulus. Flicking the leaf hard will cause the leaf to close faster whereas a gentle touch at the tip of a leaf will lead to a slower response. Thus the correct answer is option B.

The leaf lamina and apex of pitcher plant form pitcher and lid respectively. The coloured lid and nectar attract the insects which are then drowned into acidic fluid of pitcher present at it bottom. Sitting of insects stimulates the closing of lid of pitcher which makes it an induced/paratonic movement. The vital movements of plant parts which are induced by any external factor (light, temperature, water etc) are known as induced or paratonic movements as opposed to the autonomic/spontaneous movements. Thus, option A is correct. 

Heliotropism, a form of tropism, is the diurnal motion or seasonal motion of plant parts (flowers or leaves) in response to the direction of the sun. The habit of some plants to move in the direction of the sun was already known by the Ancient Greeks.

Thigmonasty is the response of a plant to touch or vibration. The Venus Flytrap an insectivorous plant shows thigmonasty. When an insect lands on its trap, the tentacles present on the two curved lobes of a single leaf, rapidly close. Hence the insect gets trapped and later killed. Thus the correct answer is option C.

Plant in order to flower require a particular day length or light period called photoperiod and response of the plants to photoperiod in terms of flowering is called photoperiodism. Photoperiodism is the response to duration and timing of light and dark periods.

On touching the Mimosa leaves the water concentration inside the plant changes due to which the plant leaves tend to get closed. This movement or response of plant is called seismonastic movement.

The branches of the secondary roots are called tertiary roots. Some of the lateral organs possess little or no geotropic sensitivty. It is thus termed as ageotropic. Example of such a plant: corolloid root of cycas.

In the case mentioned here, the plant is able to undergo flowering during all seasons of the year. it shows that the plant is insensitive to light. Photoperiodism has no great effect on the plant.