Chemistry Ozone Depletion Ozone depletion describes two distinct but related phenomena observed since the late 1970s: a steady decline of about 4% per decade in the total volume of ozone in Earth’s stratosphere (the ozone layer)‚ and a much larger springtime decrease in stratospheric ozone over Earth’s polar regions. The latter phenomenon is referred to as theozone hole. In addition to these well-known stratospheric phenomena‚ there are also springtime polartropospheric ozone depletion events. The
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Revision questions for MCB 3020 – Fall 2012 1. A portion of specific DNA molecule consists of the following sequence of nucleotide triplets. TAC GAA CTT GGG TCC This DNA sequence codes for the following short polypeptide. methionine - leucine - glutamic acid - proline - arginine Describe the steps in the synthesis of this polypeptide. What would be the effect of a deletion or an addition in one of the DNA nucleotides? What would be the effects of
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International GCSE Edexcel International GCSE in English Literature (4ET0) Teacher’s guide Issue 2 First examination 2012 Pearson Education Ltd is one of the UK’s largest awarding organisations‚ offering academic and vocational qualifications and testing to schools‚ colleges‚ employers and other places of learning‚ both in the UK and internationally. Qualifications offered include GCSE‚ AS and A Level‚ NVQ and our BTEC suite of vocational qualifications‚ ranging from Entry Level
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2007) (3) William Bonner‚ A (4) Lemieux‚ R. U.; Pavia‚ A. A. Solvation Effects on Conformational Equilibria. Studies Related to the Conformational Properties of 2-Methoxytetrahydropyran and Related Methyl Glycopyranosides. Canadian Journal of Chemistry 1969‚ 1966–1968. (5) M. L. Wolfrom‚ Donald R. Husted; the Beta to Alpha Conversion of Fully Acetylated Sugars by Alkali. J. Am. Chem. Soc.‚ 1937‚ 59 (2)‚ pp 364–365 (6) Perles‚ C (9) Spectral Database for Organic Compounds (SDBS); mass spectrum;
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Bonds All chemical bonds consist of _______ that hold groups of atoms together and make them function as a unit. A bond will form if the energy of the aggregate is ______than that of the separated atoms. ____________ – energy required to break a chemical bond Bonding involves ________________. 2 Chemical Bonds‚ cont. In general‚ there are three types of chemical bonds: I. Ionic bond: Transfer of electrons from one atom to another. Seen primarily in M + NM. Bond is an electrostatic
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them their typical luster 2) 3) Low-frequency electromagnetic fields with potential biological effects have frequencies of __________ Hz. A) 100-10‚000 B) 1-1000 C) 10-5 -10-9 3) D) 10-3 -10-5 E) 400-700 4) In the Bohr model of the atom‚ __________. A) electron paths are controlled by probability B) electrons travel in circular paths called orbitals C) electrons can have any energy D) electron energies are quantized E) both A and C 4) 5) According to the Heisenberg Uncertainty
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In the Lewis symbol for a fluorine atom‚ there are __________ paired and __________ unpaired electrons. A) 4‚ 2 B) 0‚ 5 C) 2‚ 5 D) 6‚ 1 E) 4‚1 2. Which of the following would have to gain two electrons in order to achieve a noble gas electron configuration? O Sr Na Se Br A) Sr B) Br C) Sr‚ O‚ Se D) Na E) O‚ Se 3. The electron configuration of the S2- ion is __________. A) [Ne]3s23p2 B) [Ne]3s23p6 C) [Kr]3s22p-6 D) [Ar]3s23p2 E) [Ar]3s23p6 4. The ion NO- has __________
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IGCSE Biology Notes Refined by KmQ Unit 1 : Characteristics of living things Biology is the study of living organisms. For something to be alive it needs to perform all seven functions of living things.MRS GREN Movement‚ Respiration‚ Sensitivity‚ Growth‚ Reproduction‚ Excretion‚ Nutrition. 1. Movement Most organisms are able to move their whole body even plants can shift their stem towards the sunlight and their roots move towards healthy soil. 2. Respiration IT is the breakdown of food
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Importance of Chemistry Chemistry is an important branch of science. Chemistry deals with the matter that form our environment and the transformation that the matter undergoes. Chemistry is therefore‚ useful in understanding the changes taking place in the constituents of the environment and the resulting advantages. Chemistry is connected with composition‚ structure and properties of the matter. In fact it is a science of atoms and molecules. Organic chemistry‚ inorganic chemistry‚ physical chemistry‚ analytical
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computers and television‚ and a host of essential services that we take for granted. However‚ electricity has much more important aspects because it is a fundamental feature of all matter. Electricity is the force that holds together the molecules and atoms of all
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