29 résultats pour "seeds"

• Seed - biology.

• Fruit - biology.

  from a flower with several pistils. The ovary may have a single compartment, or carpel, which houses the ovule or ovules. Or the ovary may consist of two or morecarpels, each of which may contain one or more ovules. A drupe develops from an ovary with a single carpel and is characterized by an edible exocarp and mesocarp and an inedible, hard endocarp, or pit that encloses asingle seed. Cherries, peaches, apricots, and plums are examples of drupes. Almonds also are classified as drupes, but in a...

• Gardening - biology.

  of synthetic and organic fertilizers, see Organic Farming.) Fertilizers usually are sold in packages, on which the percentage by weight of the macronutrients nitrogen (N), phosphorus (P), and potassium (K) are listed on thelabel—always in the order N-P-K. For example, a fertilizer that is labeled 10-5-3 is 10 percent nitrogen, 5 percent phosphorus, and 3 percent potassium. V PLANTING AND TRANSPLANTING Before planting seeds, gardeners prepare, or till, the soil using a variety of methods. Some...

• Flower - biology.

  insects. The sepals unfurl as the flower opens and often resemble small green leaves at the flower’s base. In some flowers, the sepals are colorful and work with thepetals to attract pollinators. E Variations in Structure Like virtually all forms in nature, flowers display many variations in their structure. Most flowers have all four whorls—pistil, stamens, petals, and sepals. Botanists callthese complete flowers. But some flowers are incomplete, meaning they lack one or more whorls. Incomplet...

• Tree - biology.

  The major parts of a tree are its roots, trunk, leaves, flowers, and seeds. These components play vital roles in a tree’s growth, development, and reproduction. A Roots Trees are held in place by anchoring organs called roots. In addition to anchoring the tree, roots also absorb water and minerals through tiny structures called roothairs. From the roots the water and mineral nutrients are carried upward through the wood cells to the leaves. Although the internal structure of most kinds of roots...

• which became a seed.

  BEAUTIFUL ANDTRUE   Mom made spaghetti fordinner thatnight. Ronatewith us.Iasked himifhe was stillinterested inbuying meafive-piece drum setwith Zildjian cymbals. Hesaid, "Yeah. Ithink thatwould begreat." "Howabout adouble basspedal?" "Idon't know whatthatis,but Ibet wecould arrange it."Iasked himwhy hedidn't havehisown family. Momsaid,"Oskar!" I said, " What? " Ron putdown hisknife andfork andsaid, "It'sOK." Hesaid, "Idid have afamily, Oskar.Ihad awife anda daughter." "Didyougetdivorced?" Helau...

• Aboriginal Australians - History.

  Until Europeans began to settle in Australia in 1788, the Aboriginal way of life was supported by hunting, gathering, and fishing. Like other hunting and gatheringpeoples, Aboriginal people had an extremely detailed knowledge of their environment, especially plant ecology and animal behavior. The deep connection betweenAboriginal people and the natural world influenced every part of their culture, including their food gathering, tools, trade, religion, art, music, language, and socialorganizatio...

• Genetics - biology.

  construct identical buildings. Just as each contractor would require a full copy of the blueprint to construct a complete building, each new cell needs a complete copy ofan organism’s genetic information to function properly. Organisms use two types of cell division to ensure that DNA is passed down from cell to cell during reproduction. Simple one-celled organisms and other organisms thatreproduce asexually—that is, without the joining of cells from two different organisms—reproduce by a proces...

• From Bulfinch's Mythology: Proserpine - anthology.

  the furrow, the seed failed to come up; there was too much sun, there was too much rain; the birds stole the seeds—thistles and brambles were the only growth.Seeing this, the fountain Arethusa interceded for the land. 'Goddess,' said she, 'blame not the land; it opened unwillingly to yield a passage to your daughter. I can tellyou of her fate, for I have seen her. This is not my native country; I came hither from Elis. I was a woodland nymph, and delighted in the chase. They praised mybeauty, bu...

• Cotton - biology.

  VII COTTONSEED Once a waste-disposal problem for gins, cottonseed is now a valuable by-product. The seed goes to oil mills, where it is delinted of its linters in an operation similar toginning. The bare seed is then cracked and the kernel removed. The meal that remains after the oil has been extracted is high in protein. Linters are used for paddingin furniture and automobiles, for absorbent cotton swabs, and for manufacture of many cellulose products such as rayon, plastics, lacquers, and sm...

• Ant - biology.

  The workers of many ant species carry a stinger within the hind end of the gaster. These ants use the stinger to defend against their enemies. In some species, workerants lack a stinger but use the tip of their gaster to squirt or dab poison at other small animals and when fighting battles with other ants, fending off predators, or killinginsects or other animals that they use as food. III PHYSIOLOGY Ants have a rigid, external skeleton called an exoskeleton that gives the soft, inner body its...

• Birding - biology.

  swallows, and rock doves nest on buildings in cities, towns, and farms. The chimney swift has abandoned hollow trees for chimneys as a nest site in urban areas.Mallards and Canada geese—once exclusively wild, migratory species—now live year-round in the open spaces found in city parks and golf courses. Nearly all purplemartins, a songbird species that once used the abandoned nests of woodpeckers or the natural cavities of cliffs or dead trees, now live primarily in structures specificallyconstru...

• From Bulfinch's Mythology: Prometheus and Pandora - anthology.

  The world being thus furnished with inhabitants, the first age was an age of innocence and happiness, called the Golden Age. Truth and right prevailed, though not enforced by law, nor was there any magistrate to threaten or punish. The forest had not yet been robbed of its trees to furnish timbers for vessels, nor had men builtfortifications round their towns. There were no such things as swords, spears, or helmets. The earth brought forth all things necessary for man, without his labour inplo...

• Liber (Free) Roman An ancient god of fertility and procreation, particularly of seeds and plants.

• Saturn (Saturnus) Roman Originally a god of agriculture, of the sowing of seeds and corn; also the god of the passage of time.

• Native Americans of North America.

  addition to smallpox and measles, explorers and colonists brought a host of other diseases: bubonic plague, cholera, typhoid fever, scarlet fever, pleurisy, mumps,diphtheria, pneumonia, whooping cough, malaria, yellow fever, and various sexually transmitted infections. Despite the undisputed devastation wreaked on Indian populations after European contact, native populations showed enormous regional variability in their response todisease exposure. Some peoples survived and, in some cases, even...

• Native Americans of North America - Canadian History.

  addition to smallpox and measles, explorers and colonists brought a host of other diseases: bubonic plague, cholera, typhoid fever, scarlet fever, pleurisy, mumps,diphtheria, pneumonia, whooping cough, malaria, yellow fever, and various sexually transmitted infections. Despite the undisputed devastation wreaked on Indian populations after European contact, native populations showed enormous regional variability in their response todisease exposure. Some peoples survived and, in some cases, even...

• Plant - biology.

  B1 Vacuoles Vacuoles are membrane-bound cavities filled with cell sap, which is made up mostly of water containing various dissolved sugars, salts, and other chemicals. B2 Plastids Plastids are types of organelles, structures that carry out specialized functions in the cell. Three kinds of plastids are important here. Chloroplasts contain chlorophyllsand carotenoid pigments; they are the site of photosynthesis, the process in which light energy from the sun is fixed as chemical energy in the b...

• Native Americans of Middle and South America.

  A line that snakes across central Mexico near the Tropic of Cancer forms the northern boundary of Mesoamerica; north of this line rainfall sharply declines and theclimate is much drier. The ancient civilizations of Mesoamerica all arose and developed in the area between this line and the Guatemalan highlands far to the south. Richvolcanic soils are found throughout much of the region. A2 People and Languages Mesoamerica was a great melting pot, home to many peoples and interrelated cultures. In...

• Ecology.

  an input of nutrients exceeding the capability of the ecosystem to process them. Nutrients eroded and leached from agricultural lands, along with sewage and industrialwastes accumulated from urban areas, all drain into streams, rivers, lakes, and estuaries. These pollutants destroy plants and animals that cannot tolerate theirpresence or the changed environmental conditions caused by them; at the same time they favor a few organisms more tolerant to changed conditions. Thus,precipitation filled...

• Ecology - biology.

  an input of nutrients exceeding the capability of the ecosystem to process them. Nutrients eroded and leached from agricultural lands, along with sewage and industrialwastes accumulated from urban areas, all drain into streams, rivers, lakes, and estuaries. These pollutants destroy plants and animals that cannot tolerate theirpresence or the changed environmental conditions caused by them; at the same time they favor a few organisms more tolerant to changed conditions. Thus,precipitation filled...

• Ecosystem.

  work. The tiny bacteria and fungi feed upon the remains of the salmon. They break down the salmon intochemical nutrients. Nutrients from the salmon go into the soil. The roots of plants along the riverbank take up the nutrients. They use the nutrients to make food. Inthis way, nutrients get recycled back through the ecosystem. WHAT CAN HARM AN ECOSYSTEM? Any change in one living or nonliving part of an ecosystem can cause changes in other parts. Droughts,storms, and fires can change ecosystems....

• Demeter - Mythology.

  disguised herself as an old woman, wearing a hood. The king’s wife, Metaneira, welcomed Demeter and asked her to look after her newborn son, Demophon. Demeter nourished the infant on ambrosia (food of the gods) and each night placed him in the fire in order to destroy all that was mortal in him, so that he would grow up like a god. One night, Metaneira spied upon her nurse and saw her place the child in the fire. Metaneira screamed with terror. Demeter was angry at the intrusion. Demete...

• Galaxy - astronomy.

  Astronomers have obtained images of young galaxies using the Keck Telescope in Hawaii and the Hubble Space Telescope, which resides in an orbit high above Earth’satmosphere and thus avoids atmospheric interference. Photos from the HST show galaxies that are as far as 13 billion light-years away from Earth, which means theyformed soon after the universe formed about 13.7 billion years ago. The galaxies appear to be spherical in shape, and may be early precursors of elliptical and spiralgalaxies....

• Hormone.

  women is called a follicle-stimulating hormone. When a follicle-stimulating hormone binds to an ovary cell, it stimulates the enzymes needed for the synthesis ofestradiol, a female sex hormone. Another gonadotropin called luteinizing hormone regulates the production of eggs in women and the production of the male sexhormone testosterone. Produced in the male gonads, or testes, testosterone regulates changes to the male body during puberty, influences sexual behavior, and playsa role in growth. T...

• Native American Art.

  folding, braiding or weaving, could also be sewn onto the hide. The production of decorated clothing and bags increased after contact with Europeans as a greater variety of textiles and other materials became available throughtrade. Imported glass beads inspired native women, who quickly adapted quillwork techniques for the creation of beaded apparel. European curvilinear and floraldesigns of the 19th century proved as meaningful for the native women who worked with them as they were for the non...

• Butterflies and Moths - biology.

  The smallest butterflies are certain blues that have wingspans of a mere 0.7 cm (0.25 in). The largest are the female giant birdwings of Papua New Guinea, whichmeasure up to 30 cm (12 in) across. Moths range in size from tiny Microlepidoptera, several groups of small moths with wings no more than 0.16 cm (0.06 in) across, togiant silk moths, such as the atlas moth, which may exceed 30 cm (12 in) in wingspan. IV REPRODUCTION AND LIFE CYCLE Butterflies locate potential mates by sight, identifyin...

• Pollination - biology.

  rapidly as in cross-pollination, because one plant with a beneficial gene can transmit it only to its own offspring and not to other plants. Self-pollination evolved laterthan cross-pollination, and may have developed as a survival mechanism in harsh environments where pollinators were scarce. IV POLLEN TRANSFER Unlike animals, plants are literally rooted to the spot, and so cannot move to combine sex cells from different plants; for this reason, species have evolved effectivestrategies for ac...

• Sudan - country.

  B Principal Cities and Political Divisions The principal city is Khartoum, the capital; other major cities include Omdurman and Khartoum North, major industrial centers, and Port Sudan, a seaport on the RedSea. Sudan is divided into 26 states. C Religion and Language About 70 percent of the people of Sudan are Muslims, some 15 percent are Christians, and most of the remainder follow traditional religions. The people of northernSudan are predominantly Sunni Muslims (Sunni Islam). Most of the pe...