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20 Cards in this Set
- Front
- Back
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What is a stimuli? |
Changes in the external or internal environment of an organism is called stimuli. |
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What is a response? |
The resulting action or movements caused by the stimuli are called responses. |
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What is a hormone? |
Plants respond to stimuli by producing chemical compounds called hormones that works as a messenger. |
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Which hormone is known as powerful growth stimulants? |
Auxins |
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What is apical dominance? |
The growth of lateral buds occurs only after the removal of apical buds. This phenomenon of the suppression of growth of lateral buds by apical buds is called apical dominance. |
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Define parthenocarpy and parthenocarpic fruits. |
Development of fruits without fertilization is called parthenocarpy. The fruits are called parthenocarpic fruits. |
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What is known as a stress hormone? Why? |
Abscisic acid is known as stress hormone of plants. Abscisic acid stimulates the closure of stomata in the epidermis and increases the tolerance of plants to various kinds of stresses . therefore, it is also known as the stress hormone. |
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What is tropism ? |
The movements of certain parts of the plant take place indirect response to external stimuli. The direction of the response is related to the direction from which the stimulus comes. Such response is known as tropism. |
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What is a Clinostat ? |
Geotropism can be demonstrated in the laboratory with the help of an instrument called Clinostat. |
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What is heliotropisms? |
The phenomenon of seeing flower heads following the sun across the sky as it moves from east to west direction. |
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Example of heliotropisms |
Sunflower |
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Eg of chemotropism. |
The movements of tentacles in Drosera towards the source of nutritions. |
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Eg of thigmotropism. |
Sweet peas, Cuscuta |
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Eg of hydrotropism. |
Shoot |
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Eg of geotropism. |
Shoot tip |
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What is the function of auxin? |
1. Promote cell elongation.2. Delay fall of leaves.3. Induce formation of parthenocarpic fruits. |
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What is the function of gibberellins? |
1. Help in stem elongation. 2. Breaks dormancy of seeds and buds. 3.Delay senescence. 4. Induce parthenocarpy. |
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What is the function of cytokinins? |
1. Stimulate cell division and cell enlargement. 2. Prevent aging of plant parts. 3. Inhibits apical dominance. |
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What is the function of Ethylene? |
1. Induces fruit ripening. 2. Promote senescence. |
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What is the function of abscisic acid? |
1. Induces dormancy of birds and seeds. 2. Inhibits seed germination and development. 3. Stimulate closing of stomata. |
