Unit 1 biology notes with diagrams to label and past paper questions!

These are my notes i typed up for unit 1.

I have combined it into a biology revison booklet.

Pictures and diagrams to label are included.

There are some past paper question included at the end of the booklet from AQA's website.

Hope you enjoy feedback will be appreciated!!

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Causes of disease
A microorganism is a single-celled organism that can't be seen
without a microscope.
They include bacteria and viruses and can sometimes be
Some organisms cause disease and these are called pathogens.

Disease is a malfunction of the body or mind which affects good

A pathogen…

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Enzymes and the digestive system
Many of the molecules in our food are polymers.
These are large complex molecules composed of chains of

Proteins and some carbohydrates are polymers. In carbohydrates
monomers are monosaccharides (contain carbon, hydrogen and
oxygen.) In proteins monomers are amino acids they contain
carbon, hydrogen,…

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Physical Breakdown- Large food is broken down into smaller
pieces by teeth to give a large surface area.

Chemical Digestion - Breaks large insoluble molecules to smaller
soluble ones. It is carried out by enzymes.

Carbon atoms readily form bonds with other carbon atoms.
Organic molecules are made up…

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The formation of a glycosidic bond by removal of water


Carbohydrates- disaccharides and
2cm3 of food tested to 2cm3 of Benedict's reagent.
Boil the test tube for 5 minutes.
No change in colour means no reducing sugar.

2cm3 of food 2cm3 of dilute hydrochloric acid and place…

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Carbohydrate Digestion
Enzymes are specific so it takes more than one to completely
breakdown a large molecule.

Starch Digestion
Firstly amylase is produced in the mouth and the pancreas. The
amylase hydrolyses the glycosidic bonds of the starch to produce
maltose. The maltose is then hydrolysed into a-glucose by

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Lactose Intolerance
You are lactose intolerant if you don't make enough of the enzyme
Lactase hydrolyses Lactose into its monosaccharide's - glucose
and galactose
Undigested lactose is fermented by bacteria in the large intestine
and can go onto cause intestinal complaints such as...
- Stomach cramps
- Excessive flatulence…

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Hydrogen bonds are formed between amino acids. This causes the
long polypeptide chain to be twisted into a 3-D shape known as
Tertiary Structure
The a-helices are twisted and folded even more to form the
tertiary structure. This is maintained by a number of bonds:
Disulfide bonds: Fairly strong…

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Induced fit model
Newer model, as substrate binds the active site changes shape
slightly to complete the fit. This is more particular as the substrate
has to fit the enzymes the right way and it has to make the active
site change shape in the right way.
It is a…

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The pH of a solution is a measure of its hydrogen ion
A change in pH alters the charges on the amino acids that make up
the active site. This means the substrate can no longer become
attached to the active site and an enzyme-substrate complex
can't be formed.…


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