Honors Biology Vocab. 21 & 22
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sophieraymer on February 15, 2012
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38 terms
Terms | Definitions |
|---|---|
 Nitrogen Fixation | The process where certain species of soil convert atmospheric nitrogen to ammonia |
| Legumes | Plants that have their own nitrogen-fixing bacteria |
| Root Nodules | Lumps on a legume's roots where the nitrogen-fixing bacteria are |
| Nitrogen | Protein and nucleic acid synthesis |
| Sulfur | Protein synthesis |
| Calcium | cell wall formation; enzyme activity |
| Root Hair | tiny outgrowths of the root's epidermal cells. They increase the surface area available for absorbing water and dissolved minerals |
| Root Pressure | helps push water up the xylem and usually operates at night |
| Endodermis | A layer of cells that surround the vascular tissue and have waxy cell walls. The wax prevents water and minerals from leaking back out of the xylem. |
| Transpiration | The loss of water through leaves due to evaporation. It creates a pull force that pulls the xylem sap up a tree because of cohesion and adhesion. |
| Tracheids | long cells with tapered ends |
| Vessel Elements | wider, shorter, less tapered cells. |
| Guard Cells | Are located around each stoma, they open and close the stoma by changing shape. |
| Sieve-Tube Members | Chain of cells that phloem sap goes through. |
| Companion Cells | Located alongside the sieve tubes, and provide proteins and other resources to the sieve-tube members. |
| Pressure-Flow Mechanism | Process by which poem sap moves through a plant |
| Source to Sink | Sugar starts at source, then moves to "sink" |
| Epiphytes | A type of plant that grows on the surface of other plants and absorbs its water and minerals from rain water that falls on their leaves. They still photosynthesize. |
| Parasitic Plants | Plants that obtain some/all of their nutrients from host plants |
| Charles Darwin and Francis | These two men did experiments that showed plant stems bend in response to light at the tip of the shoots. |
| Plant Hormones | Chemical messengers produced in the shoot tip. |
| Auxins | Promotes plant growth Produced in apical meristem Promote cell elongation Builds up on the shaded side and stimulates growth beneath the meristem The uneven growth causes the plant to bend |
| Cytokinins | Stimulate cell division Produced in actively dividing tissues like embryos, roots and fruits Slows the aging of flowers and fruits |
| Gibberellins | Produced at the tips of both stems and roots Cause a wide variety of effects Promotes cell division and elongation (like auxin's) With auxins- can influence fruit development Promotes seed germination in some species |
| Abscisic Acid | Inhibits cell devision (halts primary and secondary growth) Occurs during plant dormancy Acts as a "stress hormone" (causes stomata to close in a dehydrated plant) Also known as ABA |
| Ethylene | Stimulates fruit ripening Promotes leaf drop Only found in gas form |
| Tropisms | Growth responses that cause parts of a plant to grow slowly toward or away from a stimulus -Regulated by plant hormones, especially auxins -Not rapidly reversible |
| Thigmotropism | Response to touch |
| Phototropism | Response to light |
| Gravitropism | Response to gravity |
| Halophytes | salt-tolerant plants with adaptations such as salt glands |
| Circadian Rhythm | A biological cycle that occurs every 24 hours |
| Photoperiodism | The ability to use the environment stimulus of darkness to time time seasonal activities |
| Critical Night Length | How long it must be dark outside in order for short-day plants to bloom |
| Short-Day Plants | Flower in winter Require LONG periods of darkness EX: Chrysanthemums and poinsettias |
| Long-Day Plants | Flower in the late spring/early summer Require SHORT periods of darkness EX: Spinach, Lettuces and Irises |
| Day Neutral Plants | Flower when the plant reaches a certain stage of maturity They do no require certain day/night lengths EX: Dandelions, Tomatoes, and Rice |
| Phytochrome | Pigmented proteins that plants use to detect sunrise and sunset. When they absorb the red-light that is abundant at sunrise, they change snap to an active form that triggers a variety of plant responses |
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