(b)How does phototropism occur in a plant stem (or shoot)? Explain with the help of labelled diagrams.
(b)How does phototropism occur in a plant stem (or shoot)? Explain with the help of labelled diagrams.
The stem or shoot of the plant shows the growth movement towards sunlight. This directional movement of the plant part towards the direction of the stimulus that is sunlight is known as phototropism.
•The observation of the figure depicts that the stem of the plant responds to sunlight and bends towards it.
•This bending response of the plant stem is due to the presence of the plant hormone auxin.
•Auxin is produced by the cells present at the tip of the shoot, which prefers to stay in shade.
•The presence of sunlight on the right side of the plant allows the auxin hormone to travel towards the left side of the plant stem.
•This allows the left side of the stem to grow faster than its right side where there is no auxin.
•Therefore, the bending of the stem occurs as the left side of the stem grows faster and becomes longer as compared to the right side of the plant.
The stem or shoot of the plant shows the growth movement towards sunlight. This directional movement of the plant part towards the direction of the stimulus that is sunlight is known as phototropism.
•The observation of the figure depicts that the stem of the plant responds to sunlight and bends towards it.
•This bending response of the plant stem is due to the presence of the plant hormone auxin.
•Auxin is produced by the cells present at the tip of the shoot, which prefers to stay in shade.
•The presence of sunlight on the right side of the plant allows the auxin hormone to travel towards the left side of the plant stem.
•This allows the left side of the stem to grow faster than its right side where there is no auxin.
•Therefore, the bending of the stem occurs as the left side of the stem grows faster and becomes longer as compared to the right side of the plant.
