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1.1 Pathogens:
Pathogens are disease causing microorganisms
Disease is the symptoms displayed on a person following an infection, a malfunction of the body or mind
Infectious Disease: Caused by bacterium, virus, fungum transferred from one person to another
Non Infectious Disease: A disease that is not caused by a transmitted pathogen (e.g.…read more

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Pathogens cause disease by:
Damaging host tissue (inhibit the synthesis of DNA,RNA and proteins ­ may break down the membrane of the
host cell)
Produce toxins (have various effects such as increased water loss from cholera bacteria)
1.2 Data and Disease:
Epidemiology is the study of the incidence and pattern of a disease with regards to risk factors, the aim is to
find and prevent causes and control of the disease.…read more

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Enzymes and the Digestive System
2.1 Enzymes and digestion:
The digestive system is made up of one long tube which is an interface to the environment as food passes into the
body through it; which contains glands that produce enzymes.…read more

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There are two types of digestion:
1. Physical breakdown
2. Chemical digestion
1. Physical Breakdown:
o Food is broken down into smaller pieces by the teeth
o Makes it possible to ingest, and increases surface area for chemical digestion
o Churning of food by stomach muscles is also physical breakdown
2.…read more

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Carbohydrates ­ Monosaccharides
These are made up of a chain of individual monomers
Repeating monomer units is called a polymer
In carbohydrates, the basic monomer is sugar ­ a saccharide
o A single monomer = monosaccharide
o A pair of monosaccharides = disaccharide
o More than one disaccharide = polysaccharide
All are made up of H,O,N,C
Sweet tasting
General formula (CH2O)n - n can be any number from 3-7
The best known is glucose (C6H12O6)
2.…read more

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Enzyme Action
Enzymes are globular proteins that act as biological catalysts. They alter the rate of a chemical reaction without
undergoing permanent changes.…read more

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Lock and Key Hypothesis:
In the same way that a lock fits a key precisely, the substrate is thought to fit the enzyme perfectly. This helps
to explain the specific nature of the enzyme.
However: this suggests that the active site is a rigid structure, but scientists have noticed that the active site
can change, and therefore, it has a flexible structure.
The products have a different form to the active site, so once formed; they leave the enzyme as two/more
separate products.…read more

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Enzymes and Reaction Rates:
A rise in temperature increases the kinetic energy of molecules
This means that molecules move around more rapidly, and collide with each other more often
This increases the likelihood of a successful collision taking place
However, a rise in temperature also causes hydrogen and other bonds to break from the enzyme. This results in the
active site changing shape. The substrate fits less easily into the enzyme, so slows the rate of the reaction.…read more

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Cells and their movement
Cell structure 3.1:
The limitation of a light microscope is that there is a poor resolution. This can be solved by using a beam of electrons,
because they have a shorter wavelength.…read more


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