Có 20+ tài liệu thuộc chủ đề "sinh học thực vật"
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th ườ ng có nh a m tr ng ho c n ự ủ ắ ặ ướ c d ch ị nh y. Hoa đ n tính,cùng ho c khác g c.Th ơ ặ ố ườ ng là t bông đuôi sóc. Qu nang n t thành 3 m nh.H t ch a nhi u ả ứ ả ạ ứ...
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TR ƯỜ NG Đ I H C NÔNG LÂM HU Ạ Ọ Ế KHOA NÔNG H C Ọ. Nh hoa(Androeceum-A) ị. Nh hoa ị. C u t o c a b nh : T t c các nh trong hoa hình thành ấ ạ ủ ộ ị ấ ả ị nên b nh ,b nh c a th c v...
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From this beginning have arisen all of the vast variety of living organisms—viruses, bacteria, fungi, proto- zoans, plants, and multicellular animals—that inhabit all parts of our planet. Bacteria live in the hot thermal springs in Yel- lowstone National Park and in the deepest parts of the Pacific Ocean. Our knowledge of the processes that create and sustain life has grown...
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Taxonomy is derived from two Greek words: taxis, meaning “arrangement,” and homos, meaning “law.” It is the branch of biology concerned with applying names to each of the different kinds of organisms. Taxonomists may attempt to indicate the relationships of the organism they are describing. Individual differences must be eliminated from consideration, and features characteristic of the populations of different...
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The study of the geographic distribution of animals and the mutual influence of the environment and animals on each other is known as zoogeography. When fauna from different areas are compared, their distribution may not be consistent with the present geologic and geographic divi- sions of the Earth. For example, amphibians, reptiles, and birds of North Africa are much more...
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New fos- sil evidence, morphological studies, and comparative studies of DNA and RNA are gradually filling gaps in our knowl- edge and providing a more complete understanding of the relationships among vertebrates.. Furthermore, Garstang suggested that larval tunicates failed to metamorphose into adults but developed functional gonads and reproduced while still in the larval stage. As evidence, they cited the...
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A fleshy weblike mem- brane was attached to some of the spines.. The term gnathostome includes all of the jawed fishes and the tetrapods.. Thus, fins can resist roll if pressed on the water in the direction of the roll. fins projecting horizontally near the anterior end of the body similarly counteract pitch. Some primitive ostracoderms had such folds, although...
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Controversy surrounds the ancestor of the amphibians. These factors increased the likelihood of the skeletons being crushed before they could fossilize intact.. One of the best known osteolepiforms was Eusthenopteron foordi (Fig. Along with most of the bony fishes (Osteichthyes), rhipidistians both had gills and had air pas- sageways leading from their external nares to their lungs, so that they...
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In this method of classification, turtles are placed at the base of the tree. A cladogram giving one interpretation of the relationships among the amniotes is presented in Fig. The amniotes (reptiles, birds, and mammals) evolved from small lizardlike forms known as captorhinids that retained the skull pattern of the early tetrapods. Turtle skulls are of the anapsid type. Some...
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Reptiles, comprising over 16,150 of the 53,000 . This stage probably coin- cides with the clearing of the skin. Frequency of shedding varies with species, age, and the health of the animal.. (c) Modifications of the stratum corneum of lizards and snakes. The dor- sal arched portion of the shell is the carapace. Papers discussing various aspects of the skeleton...
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loss of the right fourth aortic arch. A cladogram of the synapsids emphasizing mammalian characteristics is pre- sented in Fig. Synapsids are characterized by a single temporal opening on each side of the skull. Therapsids: expansion of the jaw musculature. expansion of the cerebellum. The skulls show the progressive increase in size of the dentary relative to other bones in...
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10.1a) and is determined by environmental resistance factors acting on the reproductive (biotic) potential of a population. 10.1b). Such irruptions, which cause the population to exceed its carrying capacity, may be the result of such transient factors as a reduction in predators, an increase in food, a favor- able change in the weather, or any combination of these. 10.1c).. Each...
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Vertebrates are mobile animals that move about to secure food, to locate suitable homes and nesting sites, to avoid unfavorable periods of the year, and to find mates. Our understanding of the way in which animals know how, when, and where to orient and navigate around their environment has grown considerably over the last few decades.. Home range generally is...
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Likewise, the fighting between rival males in the spring might at first glance seem to deserve the epithet “antisocial” rather than “social.” The complex interactions of individuals with kin groups such as Florida scrub jays (Aphelocoma coerulescens) is much different from the way individuals of non-kin groups, such as a flock of gulls, interact. all contribute to the success of...
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Although the most intense relationships exist between mem- bers of the same species, individuals do not live apart from members of other species. The concept of interspecific competition is one of the corner- stones of evolutionary ecology. The fundamental role of an organism in the community is its niche (Elton, 1927). The niche is the occupational sta- tus of the...
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The investigator must then report objectively on the results and on conclusions drawn from them, presenting both the data and the investigator’s intepretation of the infor- mation as it relates to the hypothesis. Critical evaluation of the tech- niques—or methodology—used in any scientific investigation is extremely important. Thus, scientists constantly must be con- cerned with the selection and application of...
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The cougar (Puma concolor) is thought by many to be extirpated from most of the east- ern United States, but cougars remain in Florida and many western states as well as in Canada and Central America.. Judging from the fossil record, Peter Raven, Director of the Missouri Botanical Gardens, calculated the average life span of a species at about 4...
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Vertebrates, which have been a part of the Earth’s fauna for more than 500 million years, have evolved into many differ- ent groups that have successfully adapted to virtually every habitat. Insects (phylum Arthropoda: class Insecta) are the only other group in the Animal kingdom whose evolution sur- passes that of the vertebrates in terms of global distribution and adaptation...
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Fourth and last chamber of the ruminant stomach.. Region of the oceanic zone from approximately 4,000 to 6,000 m. teeth are attached to the summit of the jaw.. a member of the tropical order Apoda.. extends the length of the coelomic cavity. Larval form of the lamprey;. Earlike lobe of an atrium of the heart. Region of the oceanic zone...