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BIOLOGY
1 ­ Causes of disease


Pathogens

Microorganisms = bacteria and viruses Pathogens are BAD microorganisms


Disease ­ a description of certain symptoms, either physical, mental or both.

PATHOGENS:

Gain entry to the host
Colonise the tissues of the host
Resist the defences of the host
Cause damage to the…

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Pathogens affect the body by:
Damaging host tissues ­ the number of pathogens can be damaging by preventing
tissues functioning properly. Viruses inhibit the synthesis of DNA, RNA and proteins
by the host cells. Many proteins break down the membranes of the host cells
By producing toxins ­ most bacterial…

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CANCER:

Some things are beyond our control however our lifestyle can expose us
to environmental and carcinogenic factors that put us at risk.
Life style factors which contribute:

SMOKING ­ smokers and those who breathe in second hand
smoke
DIET ­ there is evidence to suggest that a low-fat, high0fibre…

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2 ­ Enzymes and the digestive system


Enzymes and digestion

Glands ­ produce enzymes that break down large molecules into small ones ready for
absorption. The digestive system therefore provides an INTERFACE with the environment
because food substances enter the body through it.




Oesophagus:
Carries food from
mouth to stomach…

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Digestion: physical breakdown (mechanical digestion) and chemical digestion

PHYSICAL BREAKDOWN/ MECHANICAL DIGESTION:-

Large food is broken into smaller pieces by structures like the teeth, making it possible to
INGEST and increasing the SURFACE AREA + for chemical digestion. Food is also
CHURNED BY MUSCLES in the stomach



CHEMICAL DIGESTION:-

Large,…

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MONOSACCHARIDES:

Are sweet tasting, soluble with a general
formula of (CH2O)n with n being between
3 and 7


Glucose: C6H12O6

TEST FOR SUGARS:

All monosaccharides and some disaccharides (E.g. maltose) are REDUCING sugars

Reduction (chemical reaction involves gaining electrons)

A reducing sugar can donate electrons to (or reduce) another chemical…

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TEST FOR NON-REDUCING SUGARS:

Other disaccharides are non-reducing as they do not change the colour of Benedict's
reagent. In order for non-reducing sugars to be detected, the disaccharide must be broken
down into monosaccharides.


TEST INSTRUCTIONS:

1. If sample is not already liquid, it must be first ground up in…

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TEST FOR STARCH:

1. Place 2cm3 of the sample into a test tube (or add two drops of the sample into a
depression on a spotting tile.
2. Add two drops of iodine solu7tion and shake/stir
3. The presence of starch is indicated by it going blue-black



Carbohydrates digestion


STARCH…

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LACTOSE INTOLERANCE

Babies produce lots of LACTASE as milk is their main source of food. As you grow older
and milk is consumed less, the production of lactase DIMINISHES during childhood. BUT
some people end up producing either little or no lactase!!!!

Some people do not produce enough lactase to…

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TEST FOR PROTEINS: Biuret test

1. Place a sample of the test solution in a test tube with an equal volume of sodium
hydroxide solution at room temp.
2. Add a few drops of very dilute (0.05%) copper (II) sulphate solution and mix gently
3. Purple = protein present blue…

Comments

Just_Georgia

so so so useful!!

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