Plants bend toward the light because -a)They need light for photosynthesisb)They need light for respirationc)Light attracts themd)Cells on the shaded side elongate moreCorrect answer is option 'D'. Can you explain this answer?

Question

Answer

In shade side Auxin is present

Answer

Under normal light conditions auxins are spread out in the plant. But when the sunlight varies auxin is broken down on the sunnier side of the stem. The higher concentration of auxin on the shady side causes the plant cells on that side to grow more so it bends towards light

Answer

Cells on the shaded side elongate more

Answer

For a plant organ to bend in response to a stimulus, differential growth of cells on either side of the organ is required. For example, for the stem of a plant to bend toward a light source, cells on the shaded side of the stem near the shoot tip must elongate faster than cells on the lighted side.

Answer

Because auxin is a plant growth hormone.in the absence of light the plant erectedin presence of light one side plant part it whichexposed to sunlight at that side auxin destroyeddue to uv rays from sun so less growth at this side so shaded side more auxin produces so more growthat shaded part of plant.thats why plant bend towards sun

Answer

Plants bend toward the light because cells on the shaded side elongate more.

Plants have a remarkable ability to detect and respond to light. This phenomenon is known as phototropism, and it is primarily driven by the growth of plant cells. When a plant is exposed to light from one direction, it will bend and grow towards the light source. This response is crucial for the plant's survival and is mediated by a hormone called auxin.

1. Phototropism and the need for light:
Plants require light for the process of photosynthesis, which is essential for their growth and development. Photosynthesis allows plants to convert light energy into chemical energy, which is used to produce glucose and oxygen. Without light, plants cannot synthesize food and ultimately starve. Therefore, it is crucial for plants to orient themselves towards a light source to maximize their exposure to sunlight.

2. The role of auxin in phototropism:
Auxin is a plant hormone that plays a significant role in various aspects of plant growth and development, including phototropism. When a plant is exposed to light, auxin accumulates more on the shaded side of the plant. This differential distribution of auxin triggers a series of physiological responses that result in cell elongation.

3. Differential cell elongation:
The accumulation of auxin on the shaded side of the plant leads to increased cell elongation in that region. This elongation causes the cells on the shaded side to grow longer compared to the cells on the illuminated side. As a result, the plant bends towards the light source, as the elongated cells on the shaded side push the plant in that direction.

4. Mechanism of cell elongation:
The differential cell elongation is primarily mediated by the loosening of cell walls on the shaded side. Auxin stimulates the activation of specific proteins known as expansins, which cause the loosening of the cell wall matrix. This loosening allows the cells to expand and elongate, leading to the bending of the plant towards the light.

Conclusion:
In conclusion, plants bend towards the light because cells on the shaded side elongate more. This response is mediated by the accumulation of auxin on the shaded side, which triggers differential cell elongation. By bending towards the light, plants can maximize their exposure to sunlight, allowing for efficient photosynthesis and overall growth and development.

Answer

For a plant organ to bend in response to a stimulus, differential growth of cells on either side of the organ is required.

Example: For the stem of a plant to bend toward a light source, cells on the shaded side of the stem near the shoot tip must elongate faster than cells on the lighted side.

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