| A | B |
|---|
| Plant hormones | Produced in minute concentrations; includes auxins, cytokinins; gibberellins and ethylene |
| gibberellins | Plant hormone that stimulates growth in stems and leaves; causes a plant to grow a long stem during bolting |
| cytokinins | Plant hormone that is synthesized in actively growing tissue; stimulates cell division and growth; delays senescence |
| abscisic acid | Plant hormone that inhibits growth and cell division; promotes plant and seed dormance; also known as ABA |
| ethylene | Gaseous plant hormone the is responsible for fruit ripening; promotes leaf abscission (loss of leaves) |
| apical dominance | Promotes growth of apical shoots (primary growth); inhibits development of axillary buds (secondary growth) |
| auxin | Plant hormone that is responsible for apical dominance; stimulates cell elongation, root growth and fruit development |
| statoliths | Specialized plastids that contain starch grains that sink to the low points in cells; help plant to respond to gravity |
| phytochrome | A photoreceptor molecule that regulates many responses to light throughout a plant's life, from germination of seeds to flowering; molecule is sensitive to red and far-red light |
| phototropism | The movement (growth) of a plant toward light |
| gravitropism | The movement (growth) of a plant toward gravity |
| thigmotropism | The movement (growth) of a plant away from touch |
| positive tropism | Move toward a stimulus; ex. phototropism |
| negative tropism | Move away from a stimulus; ex. thigmotropism |
| senescence | term to describe aging in plants |
