Solvent -Because water is polar, the slightly positive end will attract the negative ions and the positive end to the negative ions so the ions will dissolve. Means ions can be easily transported around the body
High specific heat capactiy - The energy needed to raise the temperature of 1g of a substance by 1 degree. Water remains at a fairly constant temperature, essential for life to survive
Ice is less dense than water -Water molecules are held further apart in ice so ice floats on water, which insulates the water and prevents it freezing completely meaning living things can survive below ice
High latent heat of evaporation -The energy needed to break the hydrogen bonds between water molecules. Good for cooling things - when sweat evaporates, the skin cools
Cohesive -The attraction between molecules of the same type. Helps water to flow so good for transporting substances
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Structure of water
Covalent bonds - Hydrogen and oxygen joined by covalent bonds
Water is a polar molecule - the hydrogen is slightly positive and the oxygen is slightly negative
Hydrogen bonds - the slightly negative oxygen attracts the slightly positive hydrogen
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Macromolecules and polymers
Macromolecules -Complex molecules with a large molecular mass e.g. proteins, carbohydrates and lipids
Monomers -Simple molecular units e.g. monosaccharides and amino acids
Polymers -Long chains of monomers joined together
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Making and breaking polymers
Making polymers:
Condensation reaction
Chemical bond forms
Releases a molecule of water
Breaking polymers:
Hydrolysis reaction
Chemical bond breaks
Uses a molecule of water
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Carbohydrates
What are carbohydrates:
Polymers
Made up of carbon, hydrogen and oxygen
The monomers that make up carbohydrates are monosaccharides
Formation of polysaccharides:
Condensation reaction between hydrogen atom and a hydroxyl group
Glycosidic bond forms
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Monosaccharides
Glucose:
6 carbon atoms
2 types - alpah and beta
Soluble - easily transported
Energy source in plants and animals
Ribose:
5 carbon atoms
Sugar component of RNA nucleotides
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Polysaccharides
Starch:
Energy storage in plansts
Insoluble - doesn't cause water to enter cells by osmosis
Amylose - long, unbranched chain of alpha glucose, coiled, compact
Amylopectin - long, branched chain of alpha glucose, can be broken down easily - releasing glucose
Glyogen:
Energy storage in animals
Very branched chains of alpha glucose
Can be broken down easily, releasing glucose quickly
Compact
Cellulose:
Component of cell walls
long, unbranched chains of beta glucose
Chains joined together by hydorgen bonds to form strong fibres - good for support
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