AQA AS Biology Unit 1
The Cell Membrane
Movement across Cell Membranes
The Gas Exchange System
Coronary Heart Disease
The Digestive System
Lifestyle and Disease
Defence against Disease
1 – Mathematical Requirements
2– The Unit 1 Exam
These notes may be used freely by A level biology students and teachers, and they may be copied and edited.
Please do not use these materials for commercial purposes.
I would be interested to hear of any comments and corrections. Neil C Millar (firstname.lastname@example.org)
Head of Biology, Heckmondwike Grammar School
High Street, Heckmondwike, WF16 0AH
HGS Biology A-level notes
AS Biology Unit 1
Biology Unit 1 Specification
Biological molecules such as carbohydrates and
proteins are often polymers and are based on a small
number of chemical elements.
• Proteins have a variety of functions within all living
organisms. The general structure of an amino acid.
Condensation and the formation of peptide bonds
linking together amino acids to form polypeptides.
The relationship between primary, secondary,
tertiary and quaternary structure, and protein
• Monosaccharides are the basic molecular units
(monomers) of which carbohydrates are composed.
The structure of α-glucose and the linking of αglucose by glycosidic bonds formed by condensation to form maltose and starch. Sucrose
is a disaccharide formed by condensation of glucose
and fructose. Lactose is a disaccharide formed by
condensation of glucose and galactose.
Glycerol and fatty acids combine by condensation to
produce triglycerides. The R-group of a fatty acid may be
saturated or unsaturated. In phospholipids, one of the fatty acids of a triglyceride is substituted by a phosphate group.
Iodine/potassium iodide solution for starch. Benedict’s
reagent for reducing sugars and non-reducing sugars.
The biuret test for proteins. The emulsion test for
Enzymes as catalysts lowering activation energy
through the formation of enzyme-substrate
complexes. The lock and key and induced fit models of
enzyme action. Use the lock and key model to explain
the properties of enzymes. Recognise its limitations
and be able to explain why the induced fit model
provides a better explanation of specific enzyme
properties. The properties of enzymes relating to
their tertiary structure.
Description and explanation of the effects of
temperature, competitive and non-competitive
inhibitors, pH and substrate concentration. Investigate
the effect of a specific variable on the rate of reaction
of an enzyme-controlled reaction.
The appearance, ultrastructure and function of plasma
lysosomes; ribosomes; endoplasmic reticulum and
Golgi apparatus. Apply their knowledge of these
features in explaining adaptations of other eukaryotic
HGS Biology A-level notes
The structure of prokaryotic cells to include cell wall,
plasma membrane, capsule, circular DNA, flagella and
Microscopes and Cell Fractionation
The difference between magnification and resolution.
The principles and limitations of transmission and
scanning electron microscopes. Principles of cell
fractionation and ultracentrifugation as used to
separate cell components.
The arrangement of phospholipids, proteins and
carbohydrates in the fluid-mosaic model of membrane