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InterviewSolution
| 1. |
\begin{array} { l } { \text { Name the stimuli which cause photot } } \\ { \text { ropism, chemotropism, seismonast) } } \\ { \text { and hydrotropism. } } \end{array} |
| Answer» <p>Plant tropisms are the result ofdifferential growth. This type of growth occurs when the cells in one area of a plant organ, such as a stem or root, grow more quickly than the cells in the opposite area. The differential growth of the cells directs the growth of the organ (stem, root, etc.) and determines the directional growth of the entire plant. Plant hormones, likeauxins, are thought to help regulate the differential growth of a plant organ, causing the plant to curve or bend in response to a stimulus. Growth in the direction of a stimulus is known aspositive tropism, while growth away from a stimulus is known as anegative tropism. Common tropic responses in plants include phototropism, gravitropism, thigmotropism, hydrotropism, thermotropism, and chemotropism.</p><p>Phototropismis the directional growth of an organism in response to light. Growth toward light, or positive tropism is demonstrated in many vascular plant, such asangiosperms, gymnosperms, and ferns. Stems in these plants exhibit positive phototropism and grow in the direction of a light source.Photoreceptorsinplant cellsdetect light, and plant hormones, such as auxins, are directed to the side of the stem that is furtherest from the light. The accumulation of auxins on the shaded side of the stem causes the cells in this area to elongate at a greater rate than those on the opposite side of the stem. As a result, the stem curves in the direction away from the side of the accumulated auxins and toward the direction of the light. Plant stems andleavesdemonstratepositive phototropism, while roots (mostly influenced by gravity) tend to demonstratenegative phototropism. Sincephotosynthesisconducting organelles, known aschloroplasts, are most concentrated in leaves, it is important that these structures have access to sunlight. Conversely, roots function to absorb water and mineral nutrients, which are more likely to be obtained underground. A plant's response to light helps to ensure that life preserving resources are obtained.</p><p>Heliotropismis a type of phototropism in which certain plant structures, typically stems and flowers, follow the path of the sun from east to west as it moves across the sky. Some helotropic plants are also able to turn their flowers back toward the east during the night to ensure that they are facing the direction of the sun when it rises. This ability to track the sun's movement is observed in young sunflower plants. As they become mature, these plants lose their heliotropic ability and remain in an eastward-facing position. Heliotropism promotes plant growth and increases the temperature of eastward-facing flowers. This makes heliotropic plants more attractive to pollinators.</p> <p>Please give me short answer</p> | |