Ch. 39 AP bio Vocab
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| 9220235254 | etiolation | morphological adaptations for growing in darkness |  | 0 |
| 9220235255 | de-etiolation | The changes a plant shoot undergoes in response to sunlight; also known informally as greening. | 1 | |
| 9220235257 | second messengers | Small, non-protein water soluble molecules or ions that send messages throughout the cells by diffusion. | 2 | |
| 9220235259 | plant hormone | abscisic acid, auxin, cytokinins, ethylene, gibberellins act as chemical messengers | 3 | |
| 9220235260 | tropism | A growth response that results in the curvature of whole plant organs toward or away from stimuli owing to differential rates of cell elongation. | 4 | |
| 9220235261 | phototropism | Growth of a plant shoot toward or away from light. | 5 | |
| 9220235264 | cytokinins | A class of plant hormones that retard aging and act in concert with auxin to stimulate cell division, influence the pathway of differentiation, and control apical dominance. | 6 | |
| 9220235265 | gibberellin | a hormone that stimulates plant stem elongation | 7 | |
| 9220235266 | brassinosteroids | steroid hormones in plants that have a variety of effects, including cell elongation, retarding leaf abscission, and promoting xylem differentiation. | 8 | |
| 9220235268 | ethylene | The only gaseous plant hormone. Among its many effects are response to mechanical stress, programmed cell death, leaf abscission, and fruit ripening. | 9 | |
| 9220235270 | senescence | A gradual physical decline that is related to aging and during which the body becomes less strong and efficient. | 10 | |
| 9220235271 | apoptosis | Process of programmed cell death | 11 | |
| 9220235272 | photomorphogenesis | Effects of light on plant morphology (the form of the plant). | 12 | |
| 9220235273 | action spectrum | A profile of the relative performance of the different wavelengths in photosynthesis (so green light is less absorbed, others are better absorbed). | 13 | |
| 9220235274 | blue-light photoreceptors | a type of light receptor in plants that initiates a variety of responses, such as phototropism and slowing of hypocotyl elongation | 14 | |
| 9220235275 | phytochromes | A class of light receptors in plants. Mostly absorbing red light, these photoreceptors regulate many plant responses, including seed germination and shade avoidance. | 15 | |
| 9220235276 | circadian rhythms | The 24-hour biological cycles found in humans and many other species. | 16 | |
| 9220235277 | photoperiodism | A physiological response to photoperiod, the relative lengths of night and day. An example of photoperiodism is flowering. | 17 | |
| 9220235278 | short-day plant | A plant that flowers only when the light period is shorter than a critical length. Usually fall or winter. | 18 | |
| 9220235279 | long-day plant | A plant that flowers only when the light period is longer than a critical length. Usually spring or early summer. | 19 | |
| 9220235280 | day-neutral plants | are not affected by the length of day | 20 | |
| 9220235281 | vernalization | The use of cold treatment to induce a plant to flower. | 21 | |
| 9220235283 | gravitropism | A growth response to gravity | 22 | |
| 9220235291 | virulent pathogens | pathogens against which a plant has little specific defense | 23 | |
| 9220235292 | avirulent pathogens | strains of pathogens that are mildly harmful, but do not kill the host plant | 24 | |
| 9220235293 | hypersensitive response | a plant's localized defense response to a pathogen, involving the death of cells around the site of infection | 25 | |
| 9220235294 | systemic acquired resistance | A defensive response in plants infected with a pathogenic microbe; helps protect healthy tissue from the microbe. | 26 |
