Cell wall is a fairly rigid‚ protective and supportive layer surrounding the cell external to plasma membrane of plants‚ bacteria‚ archaea‚ fungi and algae. It is absent in animals and most protists. It was first observed by Robert Hooke in 1665. It is not an entirely rigid structure as the cell wall expands due to the growth of the cell. It varies in thickness from o.1mm to I0mm.in most of the cells‚ cell wall is present from the very beginning to the last‚ but in slime molds (myxomycetes)
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Weismann‚ who noted that two cell divisions were necessary to transform one diploid cell into four haploid cells if the number of chromosomes had to be maintained. In 1911 the American geneticist Thomas Hunt Morgan observed crossover in Drosophila melanogaster meiosis and provided the first genetic evidence that genes are transmitted on chromosomes. The term meiosis was introduced to biology by J.B. Farmer and J.E.S. Moore in 1905 Meiosis i/maɪˈoʊsɨs/ is a special type of cell division necessary for
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Name: ______________________________________ Date: ________________________ Student Exploration: Osmosis Vocabulary: cell membrane‚ concentration‚ diffusion‚ dynamic equilibrium‚ osmosis‚ semipermeable membrane‚ solute‚ solvent Prior Knowledge Questions (Do these BEFORE using the Gizmo.) 1. Suppose you were trapped on a desert island with no sources of fresh water. Should you drink water from the ocean? Explain why or why not. _________________________________________________________________________
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The CELL THEORY‚ or cell doctrine‚ states that all organisms are composed of similar units of organization‚ called cells. The concept was formally articulated in 1839 by Schleiden & Schwann and has remained as the foundation of modern biology. The idea predates other great paradigms of biology including Darwin’s theory of evolution (1859)‚ Mendel’s laws of inheritance (1865)‚ and the establishment of comparative biochemistry (1940). Ultrastructural research and modern molecular biology have
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DETERMINATION OF THE WATER POTENTIAL OF POTATO TUBER CELLS. Method. Five sucrose solutions with varying molarity and one control containing distilled water were prepared and poured into test tubes. The potato discs were dried‚ weighed and added to the test tubes. The discs were then weighed again after a period of 24 hours. The percentage change in mass was then calculated. Apparatus.  Specimen tubes with stoppers x6  1cm3 diameter cork borer  razor
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Sep. 21‚ 2014 Stem Cells Stem cells are the beginning of organism creation and have the potential to separate‚ becoming any kind of organism‚ endlessly. These cells have not gone through the process known as differentiation‚ which gives the cell a specific function. Technically‚ due to research over the recent years‚ scientists could grow certain organs with through stem cells because of the fact that these cells can be manipulated early on. There are multiple stem cells that have been determined
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STAGES OF MITOSIS Name +r-« ~ber the following six diagrams of the stages of mitosis in animal cells in the proper _ .Jr. Label each stage with the proper name. 5 .- Ie-I )0 0 ohCtJ~ I the same for the following diagrams of mitosis in plant cells. 5 - --:r n-k/l ohG(~ i Biology IF8765 29 +-eloph~ ©Instructional Fair‚ Inc. Name: --.t.&=-+~+--------\ ( Cellular Division DIRE C T ION S: Answer the following math problems. Use the space below each problem or a separate piece of paper
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CHAPTER 36 PLANT CELLS The first barrier to form between daughter cells is the middle lamella. Daughter cells expand to their final size and make polysaccharides for a primary wall. After expansion stops waterproofing materials are added for a secondary wall. Water and dissolved materials move from cell to cell by way of pit pairs. A pit is a thin spot in the primary wall where the secondary wall is absent or separated from the primary wall by a space. Strands of cytoplasm called
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Cell Cycle Definition- The process of the cell to divide into new cells. Interphase Description- the phase that occurs before cell division‚ the preparation for cell divisions Stages: G1- Rapid growth of the cell‚ metabolic activity. S- Synthesis‚ DNA replication. G2- Getting ready for cell division. Centrioles replicate Mitosis and Cell Division Function- To grow repair and maintain the cells in the body along with the reproduction of those cells. Results- Two identical daughter
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him or her having Sickle Cell Disease. What this is is it’s a disease that is genetically inherited and it involves the red blood cells. Mutations in the HBB gene cause this disease. This disease is inherited in an autosomal recessive pattern‚ which means both copies of the gene in each cell will have mutations. The parents of offspring with an autosomal recessive gene each carry one copy of the mutated gene. The blood cells form an abnormal crescent shape (normal cells are in a disk form). The
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