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18 Cards in this Set
- Front
- Back
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Frequently occurring chemical elements in living things
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Carbon (C)
Hydrogen (H) Oxygen (O) Nitrogen (N) - 99% mass of living things - Valencies of 1-4, stable covalent bonds |
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Other elements needed by living things
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Sulphur, Calcium, Phosphorus, Iron, Sodium, Magnesium, other stuff
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Function of C, H, O, N
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- organic compounds e.g. lipids, carbohydrates
- H&O --> water (vital) - N --> animo acids, nucleic acids |
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Function of Sulphur
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- amino acids and proteins
- vitamins |
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Function of Calcium
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- cell wall formation (plants)
- bone constituent (animals) - reacts in muscle fibre contraction, blood clotting, synapses (animals) - enzyme cofactor - heat resistance of bacterial endospores (prokaryotes) |
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Function of Phosphorus
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- synthesis of nucleotides and ATP
- bone constituent (animals) |
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Function of Iron
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- electron transport molecule constituent
- chlorophyll synthesis (plants and photosynthetic prokaryotes) - haem, part of haemoglobin; cytochromes (animals) |
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Function of Sodium
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- with potassium, membrane function
- nerve impulse transport (animals) |
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Function of Magnesium
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- chlorophyll (plants and photosynthetic prokaryotes)
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Structure of water molecules
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- 1 atom of O + 2 atoms of hydrogen (covalent)
- triangular - unequal distribution of electrical charge |
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Polarity of water
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- polar covalent bond (unequal sharing of electrons)
- hydrogen bond |
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Hydrogen bond formation
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- charged regions attracted to oppositely charged regions of neighbouring molecules
- multiple partners |
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Thermal properties of water
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- lot of energy required for water molecules to escape from each other
- liquid at room temperature |
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Cohesive properties of water
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- cohesive (molecules stick together) & surface tension (difficult to break surface)
- skin-like layer, highest surface tension |
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Solvent properties of water
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- ionic and polar (hydrophillic) substances
- formation of hydrating shells |
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Coolant
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* high specific heat capacity (high energy needed to change temperature)
- body temperatures do not change rapidly - water body temperature stable * high latent heat of vaporisation, fusion - change state = high energy - lots of heat can be loss with negligible loss of water --> sweating |
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Medium for metabolic reactions
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- transparency --> light for photosynthesis
- low viscosity --> blood/xylem+phloem substances flow easily - low energy needed to push - hydrolysis + substrate |
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Transport medium
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- adhesive properties --> xylem transport (against gravity)
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