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1 | | How do plants bend toward light? |
| | A) | With the extra energy provided by the light, the plant can grow selectively in the direction with more light. |
| | B) | A hormone, auxin, is distributed in such a way that it promotes cell elongation in the tissue farthest from the light. |
| | C) | Light causes inhibition of growth in the cells closest to it by creating a conformational change in a steroid receptor. |
| | D) | Cells closest to the light become photobleached, making them unable to grow as fast as cells farther from the light. |
| | E) | Blue light receptors near the light signal gene activation which changes the plant's growth aspect. |
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2 | | What role does auxin play in the growth of shoots exhibiting gravitropic response? |
| | A) | It causes apoptosis (programmed cell death) in cells, which therefore causes bending toward the region where auxin has accumulated. |
| | B) | It allows rapid cell growth, so by accumulating in the lower regions of the plant, it bends the tissues upward. |
| | C) | Auxin causes mutations in genes, making the cell less efficient in growing. As it accumulates at the tops of horizontal branches, it stimulates bending upwards. |
| | D) | All of these possibilities are being investigated as to the role of auxin in gravitropism. |
| | E) | Two of the above are valid explanations for the effect of auxin in plant growth. |
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3 | | The pulvinus is involved in rapid response to touch in many leguminous species. How does it operate? |
| | A) | It generates a charge in the plant's nervous system, which is transduced to distant cells. These lose water rapidly through their stomata to collapse. |
| | B) | Genes in the pulvinus are stimulated for rapid cell growth in the side farthest from the stimulation. |
| | C) | Apoptosis (programmed cell death) occurs in cells nearest the stimulation. |
| | D) | An electrical stimulation of cell membranes causes pumping of ions from one side of the pulvinus to the other. This causes the depleted cells to collapse while the other cells swell. |
| | E) | None of the above explain the function of a pulvinus. |
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4 | | Which of the following can act as a stimulus for a seed that is breaking dormancy? |
| | A) | Appropriate temperatures |
| | B) | Water leaching out inhibitory chemicals |
| | C) | Mechanical cracking of the seed coat |
| | D) | All of these have been shown to allow seeds to break dormancy. |
| | E) | Only appropriate temperatures and inhibitory chemicals have been demonstrated to break dormancy. |
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5 | | How does phytochrome indicate the presence of red light? |
| | A) | It undergoes a conformational change which allows it to be ubiquitinated and subsequently destroyed by a proteasome. |
| | B) | It binds to promoters of specific genes to turn them on |
| | C) | It binds to promoters of specific genes, preventing RNA polymerase from binding and therefore blocks expression. |
| | D) | It binds to chlorophyll to improve its ability to absorb light. |
| | E) | It blocks the Calvin cycle, allowing the plant's metabolism to concentrate on signal transduction. |
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6 | | What organelle participates most directly in gravity perception? |
| | A) | Amyloplasts |
| | B) | Auxins |
| | C) | Gravoliths |
| | D) | The endoplasmic reticulum |
| | E) | The nucleus |
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7 | | What is the definition of thigmotropism? |
| | A) | Specific responses caused by hormone accumulation in plant tissues |
| | B) | Irreversible changes in tissue structure because of physical stimulation |
| | C) | Patterns of growth caused by repeated, regular contact with a stimulus |
| | D) | Coiling of plant tissues around nearby, cylindrical objects |
| | E) | Directional growth of plant parts due to contact with something |
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8 | | The abscission zone of a leaf is defined by the axillary bud, which is sloughed off during cold temperatures. |
| | A) | True |
| | B) | False |
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9 | | Which plant hormone is volatile, consisting of only two carbons? |
| | A) | Auxin |
| | B) | Cytokinin |
| | C) | Ethylene |
| | D) | Giberellin |
| | E) | Brassinosteroid |
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10 | | Mature plants may become __________ in dry or cold seasons in order to survive long periods that are unfavorable for growth. |
| | A) | dormant |
| | B) | dehydrated |
| | C) | photoperiodic |
| | D) | thigmonastic |
| | E) | gravitropic |
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11 | | Cytokinins are related to or derived from which purine base? |
| | A) | adenine |
| | B) | thymine |
| | C) | guanine |
| | D) | cytocine |
| | E) | uracil |
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12 | | ________________ is directional growth responses of plants to a unidirectional source of light. |
| | A) | Gravitropism |
| | B) | Thigmotropism |
| | C) | Dormancy |
| | D) | Phototropism |
| | E) | Thermotropism |
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13 | | Charles Darwin and his son experimented with which plant growth response? |
| | A) | gravitropism |
| | B) | circadian rhythms |
| | C) | phototropism |
| | D) | heat shock |
| | E) | thermotropism |
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14 | | The plant hormones known as ___________ are structurally similar to animal steroid hormones. |
| | A) | brassinosteroids |
| | B) | oligosaccharides |
| | C) | cytokinins |
| | D) | auxins |
| | E) | abscisic acids |
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15 | | Which of the following traits does not apply to brassinosteroids? |
| | A) | They were first discovered in pollen. |
| | B) | They are released from the cell wall by enzymes secreted by pathogens. |
| | C) | Their functions overlap with those of auxins and gibberellins. |
| | D) | Their characteristics are similar to animal steroids. |
| | E) | They may have evolved before the evolutionary divergence of plants and animals. |
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