Term
|
Definition
| One of the three taxonomic domains of life consisting of unicellular prokaryotes distinguished by cell walls made of certain polysaccharides not found in bacterial or eukaryotic cell walls, plasma membranes composed of unique isoprene-containing phospholipids, and ribosomes and RNA polymerase similar to those of eukaryotes. |
|
|
Term
|
Definition
| Any organism that can synthesize reduced organic compounds from simple inorganic sources such as CO2 or CH4. Most plants and some bacteria and archaea are autotrophs. Also called primary producer. |
|
|
Term
|
Definition
| One of the three taxonomic domains of life consisting of unicellular prokaryotes distinguished by cell walls composed largely of peptidoglycan, plasma membranes similar to those of eukaryotic cells, and ribosomes and RNA polymerase that differ from those in archaeans or eukaryotes |
|
|
Term
|
Definition
| An organism that produces ATP by oxidizing inorganic molecules with high potential energy such as ammonia (NH3) or methane (CH4). |
|
|
Term
|
Definition
| An organism that produces ATP by oxidizing organic molecules with high potential energy such as sugars. Also called organotroph. Compare with chemolithotroph. |
|
|
Term
|
Definition
| A technique for identifying and studying microorganisms that cannot be grown in culture. Involves detecting and amplifying copies of certain specific genes in their DNA, sequencing these genes, and then comparing the sequences with the known sequences from other organisms. |
|
|
Term
|
Definition
| The theory that mitochondria and chloroplasts evolved from prokaryotes that were engulfed by host cells and took up a symbiotic existence within those cells, a process termed primary endosymbiosis. In some eukaryotes, chloroplasts originated by secondary endosymbiosis, that is, by engulfing a chloroplast-containing protist and retaining its chloroplasts. |
|
|
Term
|
Definition
| In organisms undergoing alternation of generations, the multicellular haploid form that arises from a single haploid spore and produces gametes. A female gametophyte is commonly called an embryo sac; a male gametophyte, a pollen grain. Compare with sporophyte. |
|
|
Term
|
Definition
| In organisms undergoing alternation of generations, the multicellular diploid form that arises from two fused gametes and produces haploid spores. Compare with gametophyte. |
|
|
Term
|
Definition
| Members of several phyla of green plants that lack vascular tissue including liverworts, hornworts, and mosses. Also called nonvascular plants. |
|
|
Term
|
Definition
| The female reproductive organ in a flower. Consists of the stigma, to which pollen grains adhere; the style, through which pollen grains move; and the ovary, which houses the ovule. Compare with stamen. |
|
|
Term
|
Definition
| Describing a plant that sheds leaves or other structures at regular intervals (e.g., each fall) |
|
|
Term
|
Definition
| Any plant that has two cotyledons (embryonic leaves) upon germination. The dicots do not form a monophyletic group. Also called dicotyledonous plant. Compare with eudicot and monocot. |
|
|
Term
|
Definition
| An unusual form of reproduction seen in flowering plants, in which one sperm nucleus fuses with an egg to form a zygote and the other sperm nucleus fuses with two polar nuclei to form the triploid endosperm. |
|
|
Term
|
Definition
| A triploid (3n) tissue in the seed of a flowering plant (angiosperm) that serves as food for the plant embryo. Functionally analogous to the yolk in some animal eggs. |
|
|
Term
|
Definition
| A nonparasitic plant that grows on trees or other solid objects and is not rooted in soil. |
|
|
Term
|
Definition
| A member of a monophyletic group (lineage) of angiosperms that includes complex flowering plants and trees (e.g., roses, daisies, maples). All eudicots have two cotyledons, but not all dicots are members of this lineage. Compare with dicot and monocot. |
|
|
Term
|
Definition
| In organisms undergoing alternation of generations, the multicellular haploid form that arises from a single haploid spore and produces gametes. A female gametophyte is commonly called an embryo sac; a male gametophyte, a pollen grain. Compare with sporophyte. |
|
|
Term
|
Definition
| A paraphyletic group of photosynthetic organisms that contain chloroplasts similar to those in green plants. Often classified as protists, green algae are the closest living relatives of land plants and form a monophyletic group with them. |
|
|
Term
|
Definition
| Any plant that has a single cotyledon (embryonic leaf) upon germination. Monocots form a monophyletic group. Also called a monocotyledonous plant. Compare with dicot. |
|
|
Term
|
Definition
| One of the protective leaflike organs enclosing a flower bud and later supporting the blooming flower. |
|
|
Term
|
Definition
| The hairlike structure that anchors a bryophye (nonvascular plant) to the substrate. |
|
|
Term
|
Definition
| A spore-producing structure found in seed plants, some protists, and some fungi (e.g., chytrids). |
|
|
Term
|
Definition
| The male reproductive structure of a flower. Consists of an anther, in which pollen grains are produced, and a filament, which supports the anther. Compare with carpel. |
|
|
Term
|
Definition
| In vascular plants, a long, thin water-conducting cell that has gaps in its secondary cell wall, allowing water movement between adjacent cells. Compare with vessel element. |
|
|
Term
|
Definition
| A plant hormone that slows growth, often antagonizing actions of growth hormones. Two of its many effects are to promote seed dormancy and facilitate drought tolerance. |
|
|
Term
|
Definition
| A term that primarily refers to indoleacetic acid (IAA), a natural plant hormone that has a variety of effects, including cell elongation, root formation, secondary growth, and fruit growth. |
|
|
Term
|
Definition
| Describing a pathogen that can only mildly harm, but not kill, the host. |
|
|
Term
|
Definition
| A type of light receptor in plants that initiates a variety of responses, such as phototropism and slowing of hypocotyl elongation. |
|
|
Term
|
Definition
| Any of a class of related plant hormones that retard aging and act in concert with auxin to stimulate cell division, influence the pathway of differentiation, and control apical dominance. |
|
|
Term
|
Definition
| The changes a plant shoot undergoes in response to sunlight; also known informally as greening. |
|
|
Term
|
Definition
| The only gaseous plant hormone. Among its many effects are response to mechanical stress, programmed cell death, leaf abscission, and fruit ripening. |
|
|
Term
|
Definition
| Plant morphological adaptations for growing in darkness. |
|
|
Term
|
Definition
| Any of a class of related plant hormones that stimulate growth in the stem and leaves, trigger the germination of seeds and breaking of bud dormancy, and (with auxin) stimulate fruit development. |
|
|
Term
|
Definition
| In multicellular organisms, one of many types of secreted chemicals that are formed in specialized cells, travel in body fluids, and act on specific target cells in other parts of the body to change their functioning. |
|
|
Term
|
Definition
| A type of light receptor in plants that mostly absorbs red light and regulates many plant responses, such as seed germination and shade avoidance. |
|
|
Term
|
Definition
| A signaling molecule in plants that may be partially responsible for activating systemic acquired resistance to pathogens. |
|
|
Term
|
Definition
| A small, nonprotein, water-soluble molecule or ion, such as a calcium ion (Ca2+) or cyclic AMP, that relays a signal to a cell’s interior in response to a signaling molecule bound by a signal receptor protein. |
|
|
Term
|
Definition
| (1) In plants, a specialized plastid that contains dense starch grains and may play a role in detecting gravity. (2) In invertebrates, a grain or other dense granule that settles in response to gravity and is found in sensory organs that function in equilibrium. |
|
|
Term
| systemic acquired resistance |
|
Definition
| A defensive response in infected plants that helps protect healthy tissue from pathogenic invasion. |
|
|
Term
|
Definition
| A growth response that results in the curvature of whole plant organs toward or away from stimuli due to differential rates of cell elongation. |
|
|
Term
|
Definition
| The natural process by which nitrogen, either from the atmosphere or from decomposed organic material, is converted by soil bacteria to compounds assimilated by plants. This incorporated nitrogen is then taken in by other organisms and subsequently released, acted on by bacteria, and made available again to the nonliving environment. |
|
|
Term
|
Definition
| The conversion of atmospheric nitrogen (N2) to ammonia (NH3). Biological nitrogen fixation is carried out by certain prokaryotes, some of which have mutualistic relationships with plants. |
|
|
Term
|
Definition
| A swelling on the root of a legume. Nodules are composed of plant cells that contain nitrogen-fixing bacteria of the genus Rhizobium. |
|
|
Term
|
Definition
| A plowing technique that involves creating furrows, resulting in minimal disturbance of the soil. |
|
|
Term
|
Definition
| A soil bacterium whose population size is much enhanced in the rhizosphere, the soil region close to a plant’s roots. |
|
|
Term
|
Definition
| The soil region close to plant roots and characterized by a high level of microbiological activity. |
|
|
Term
|
Definition
| A mixture of particles derived from rock, living organisms, and decaying organic material (humus). |
|
|
