AQA Biology Unit 1 Revision Notes

Hello All,

Here is my complete set of AQA Biology Unit 1 revision notes. They have been written against the specification and from variaty of resourse these being: Nelson Thornes AQA Biology AS textbook, CGP AS-Level Biology (AQA), the internet (Wiki, S-cool, etc...) and many teachers notes. 

Feel free to download and check them out. I hope they come in useful to you!

All the best for the exam period.

Thanks,

Ben Bonham

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Page 1

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Causes of Disease
Disease
Disease is not a single thing but a description of certain symptoms, physical mental or both. It suggests a
malfunction of body or mind having an adverse effect on good health.



Pathogens
- A pathogen is an organism that causes disease.
- Pathogens include microorganisms and…

Page 2

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Some disease like Heart Disease and Cancer have a number of causes like; lifestyle (diet, exercise,
smoking), genetics and pathogens.


Data and Disease
Analysing and interpreting data of disease
Epidemiology is the study of the incidence and pattern of a disease with a view to finding means to
preventing and…

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Enzymes and the Digestive
System
Major Parts of the Digestive System
The human digestive system is made up of a long muscular tube and its associated glands. These glands
secrete enzymes that break down large molecules into smaller ones for absorption.


Salivary Glands: Pass their secretions
via a duct into…

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Stages of Digestion
There are 2 main stages of digestion:
1. Physical breakdown,
2. Chemical breakdown.
Physical breakdown: When food is too large it is broken down into smaller pieces by means of structures
such as teeth. This makes it possible to swallow and increases the surface area to help…

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Proteins
Structure of amino acids
Amino acids are the basic monomer unit which combine with another amino acid to form a dipeptide
more than this join up together to make a polymer called a polypeptide. Polypeptide combine to form
proteins.
Every amino acid has a central carbon atom eith 4…

Page 6

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other. This peptide bond under, suitable conditions, can be broken by the addition of water which is




called hydrolysis.


Protein: Primary structure
Many amino acid monomers can be joined together in a process called polymerisation. This chain of
hundreds of amino acids is called a polypeptide. The sequence of amino…

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Proteins made from a single polypeptide chain have the tertiary structure as their final 3-D shape.
The 3-D shape makes proteins distinctive and allows it to recognise, and be recognised by, other
molecules.


Protein: Quaternary Structure
Larger proteins form complex molecules containing multiple polypeptide chains that are linked in various…

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- Add an equal volume of Benedict's reagent.
- Heat the mixture in a gentle boiling water bath for 5 minutes.
If a reducing sugar is present an insoluble red precipitate of copper(I) oxides is formed in the blue
solution.
The concentration of the reducing sugar will affect the final…

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Testing for non-reducing sugars
Some disaccharides are reducing sugars (e.g. maltose) but others are non-reducing sugars that have no
change when mixed with Benedict's solution. To test for what type sugar is in your sample you need to:
1. Test for a reducing sugar: Benedict's Test, no positive result so:…

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- The epithelial lining also produces sucrase (sucrose Glucose + Fructose) and lactase (Lactose
Glucose + Galactose)


Lactose intolerance
- Milk is the only food for most babies so they have a lot of lactase to hydrolyse the lactose in milk.
- Milk gradually forms less part of the babies…

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