REVSION WORLD A LEVEL

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Revision IDEAS

November 01, 2015

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Biology: Biological molecules- Water

What our body is made up of? Group name monomers polymers % dry mass Proteins amino acids polypeptides 50 nucleic acids nucleotides polynucleotides 18 carbohydrates monosaccharides polysaccharides 15 lipids fatty acids and glycerol Triglycerides 10 polarity density solvent capillary action adhesion cohesion surface tension Water: Water has a number of important properties essential for life. Many of the properties below are due to the hydrogen bonds in water. Here are some of the reasons why water is important for us: The unique properties of water: · Solvent . Because it is charged, water is a very good solvent . Charged or polar molecules such as salts, sugars, amino acids dissolve readily in water and so are called hydrophilic ("water loving"). Uncharged or non-polar molecules such as lipids do not di

EDEXCEL CORE 1 MAY 18TH - Unofficial Markscheme

EDEXCEL C1: Q1) 2/5X^3-8X^1/2+3X+C Q2) y=6X+2 Q3)a) 2root 2 b) 3root 6 Q4a) stretch in y-direction by scale factor 3. b) translate by vector (0,-4) (downwards) Q5) X=-1/7 ; Y= -1/3 X=-3/7 ; Y=1/3 Q6)a) A2= 5-4K A3= 5-5K+4K^2 B) 4K^2-9k+1 C)I) I forgot to do again lol C)II) 500 (OMFG WAT WAS THIS?!) Q7)dy/dx= 6X+2X^-2/3+X^1/2+7/6(X^3/2) Q8)a) proof of inequality- had to substitute the 2 equations and the discriminant<0 b) 1/2<P<9/2 Q9)a) £225 b) £180 c) £1710 d) 18 years from 10 years old so 27 years old Q10)a) 5Y+3X-44=0 b) R: (44/3,0) c) area of Quad: 76 units (this proved extremely difficult when splitting into 2 triangles, so I split in 2 triangles and a rectangle) Q11)a) dy/dx= 6X^2+2KX+5 b) K=41/8=5.125 c) y co-ordinate- 49/2 D) 2y-17x-83=0

Immunity

Non-specific immunity Ø Many pathogens cannot cause disease due to non specific barriers and cellular defences, that prevent them from entering the body Ø Physical barriers- prevent entry of pathogens and micro-organisms when they are in contact. (1st line of defence) o Tears o Eyelashes o Skin o Mucous o Ciliated cells Ø Skin- dry and strong, outer layers of cells are shed taking bacteria with them. Ø Eye lashes- respond to foreign bodies in the region of the eyes Ø Mucous- traps dirt and bacteria Ø Cilia- brushes the trapped dirt and bacteria away Ø Tears- lysosomes which destroy bacterial cells Ø HCL- present in stomach acid Ø Skin: o Secretes sebum which lowers the pH- inhibits pathogen growth o Sweat contains salts- hard for certain types of bacteria to survive Ø Tears and eye lashes: o Tears contain lysosomes which are enzymes that can destroy bacterial cells and prevents entry of pathogens in

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