Complete Unit One Biology Revision Guide Based on AQA Textbook

Tina and I made this revision guide together, which bullet points the entire contents of Unit one of the AQA biology textbook in order as it appears. Its quite long, but each section is headed and written in short, bullet point form, so just scroll down to the bit that you want (or search for a heading using CTRL+F). Hope it helps :)

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  • Created by: Jessica
  • Created on: 13-05-12 18:34
Preview of Complete Unit One Biology Revision Guide Based on AQA Textbook

First 73 words of the document:

Causes of Disease -
Pathogens
A pathogen is: a single celled organism (bacterium, virus, or other microorganism)
that can cause disease.
» To be classed as a pathogen they must:
Gain entry to the host
Colonise the tissues of the host
Resist the defences of the host
Cause damage to the host tissues
» It is too small to be seen without a microscope.

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Can cause disease by damaging host tissues, i.e., preventing tissues from
functioning properly by breaking down the membranes of the host cells, or by
producing toxins.
Pathogens cause an infection which may lead to a disease
(recognisable symptoms)
» They gain entry to the body via
Gas exchange system
Digestive system
A break in the skin
Enzymes and Digestion
An enzyme is: a protein that acts as a catalyst and alters the speed of a bio-chemical
reaction.…read more

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Pass secretions via a duct into the mouth
Contain amylase, which breaks down starch into maltose
» Pancreas
Situated below the stomach
Produced pancreatic juice, and contains protease to digest proteins,
lipase for lipids and amylase for starch.
Carbohydrates ­ Monosaccharides
Monosaccharides are: sweet tasting, soluble substances, with a general formula of
(CH2O)n ­ N being a number between 3 and 7.…read more

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A condensation reaction is: when water is removed as
monosaccharides join together. Here a glycosidic bond is formed.
When water is added under the right conditions, the bond breaks
down, in a process called hydrolysis.
The test for non-reducing
Test for non-reducing sugars:
1. Complete the test for reducing sugars first ­ fail
2. Add food sample to dilute hydrochloric acid, and place for five minutes in a
gently boiling water bath.
This will hydrolyse any disaccharide present into monosaccharides
3.…read more

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In intestines, it mixes with pancreatic amylase, which continues the hydrolysis
of starch
Alkaline salts maintain the PH7
Maltase is produced in the epithelial lining and hydrolyses the maltose
into alpha glucose
Disaccharide digestion
» Sucrose
Food must be physically broken down in order to release
Epithelial lining in the intestine produces Sucrase
hydrolyses the single glycosidic bond to produce
monosaccharides: Glucose and Fructose
» Lactose
Sugar found in milk
Digested in the small intestine
Epithelial lining produces lactase
Hydrolyses the glycosidic bond that link…read more

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Carboxyl group (COOH)
Hydrogen atom (H)
R group (variety of different chemical group)
Formation of a peptide bond
» Amino acid monomers combine to make a dipeptide with a peptide bond
» Condensation reaction
OH from carboxyl group and H from another amino acid
» N and C form a peptide bond
Primary Structure ­ Polypeptides
» Series of condensation reactions join together
many monomers (Polymerisation)
Chain of amino acids form a polypeptide
Polypeptides form a protein
Primary structure of any protein
Determines shape and…read more

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Combination of a number of different polypeptide.
» Other molecules such as iron etc. associated with it to activate the complex.
Test for Proteins
1. Place sample of solution with equal volume of sodium hydroxide at room
temp.
2. Few drops of dilute copper sulphate and mix gently.
3. Purple colouration indicated presence of proteins.
4. Remaining blue indicates no protein is present.
Enzymes ­ Enzyme Action
Enzymes are: Globular proteins that act as
catalysts.…read more

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Explains how other molecules can effect enzyme activity
How activation energy is lowered
Enzymes ­ Factors Affecting Action
Temperature
» A rise in temperature increases kinetic energy
Molecules move around more rapidly and so more collide with enough
force to form a complex.
» If it is too hot the enzyme gets denatured.
PH
» If the PH differs too much from that of the optimum, it causes bonds
(tertiary structure) to break.…read more

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End Product inhibits enzyme A.
Quantity of end product increases above normal.
This will cause greater inhibition of enzyme A.
Less product will be produced and its level will return to normal.
*And vice Versa*
Magnification
Magnification =
Cell Fractionation
Cell Fractionation: Cells broken up, organelles separated out.
» Before this, tissue is placed in a solution.…read more

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Transmission Electron Microscope (TEM)
Electron gun produces beam of electrons focused on
specimen by a condenser electron magnet.
Beam passed through a thin section of specimen, specimen
absorbs electrons; so appear dark.…read more

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