Y12: AS Biology

Biol AS

In year 12 we follow the AQA Biology specification. The course consists of 3 units which are assessed at the end of the year.

Unit 1 – Biology & Disease

This unit consists of the following sections and is assessed by a 1 hr 15 min examination.

Disease may be caused by infectious pathogens or may reflect the effects of lifestyle

The digestive system provides an interface with the environment. Digestion involves enzymic hydrolysis producing smaller molecules that can be absorbed and assimilated
The digestive system
Enzyme action
Enzyme properties
Carbohydrate digestion

Substances are exchanged between organisms and their environment by passive or active transport across exchange surfaces. The structure of plasma membranes enables control of the passage of substances across exchange surfaces.
Plasma membranes
Active transport

The lungs of a mammal act as an interface with the environment. Lung function may be affected by pathogens and by factors relating to lifestyle
Lung function
The biological basis of lung disease

The functioning of the heart plays a central role in the circulation of blood and relates to the level of activity of an individual. Heart disease may be linked to factors affecting lifestyle.
Heart structure and function
The biological basis of heart disease

Mammalian blood possesses a number of defensive functions
Principles of immunology


Unit 2 – The variety of living organisms

This unit consists of the following sections and is assessed by a 1 hr 45 min examination.

Living organisms vary and this variation is influenced by genetic and environmental factors
Investigating variation
Causes of variation

DNA is an information-carrying molecule. Its sequence of bases determines the structure of proteins, including enzymes
Structure of DNA
Genes and polypeptides
DNA and chromosomes

Similarities and differences in DNA result in genetic diversity
Genetic diversity

The variety of life is extensive and this is reflected in similarities and differences in its biochemical basis and cellular organisation

During the cell cycle, genetic information is copied and passed to genetically identical daughter cells
Replication of DNA
Cell cycle

In complex multicellular organisms, cells are organised into tissues, tissues into organs and organs into systems
Cell differentiation

Factors such as size and metabolic rate affect the requirements of organisms and this gives rise to adaptations such as specialised exchange surfaces and mass transport systems.
Size and surface area
Gas exchange
Mass transport
The blood system
The passage of water through a plant

Classification is a means of organising the variety of life based on relationships between organisms and is built around the concept of species
Principles of taxomony

Originally, classification systems were based on observable features but more recent approaches draw on a wider range of evidence to clarify relationships between organisms.
Genetic comparisons

Adaptation and selection are major components of evolution and make a significant contribution to the diversity of living organisms
Genetic variation in bacteria

Biodiversity may be measured within a habitat
Species diversity
Index of diversity

Unit 3 – Investigative and practical skills in AS biology (ISA)

This unit assesses students’ practical skills and is carried out from March onwards. The topics for assessment change each year however students are required to complete the following;

A practical investigation provided by the examination board. Students should construct a table of results and plot a graph of their data by the end of the allocated time.

A 1 hour paper will be given for students to carry out analysis. The paper is split in to two sections-
Section A – This consists of a number of questions relating to the student’s own data
Section B – This section will provide a further set of data related to the original experiment. A number of questions relating to the analysis and evaluation of the data then follow.

The 3 units for assessment are weighted in the following way;

Unit 1 BIOL1                                                                                                  Biology & disease
Written examination – (60 marks/100 UMS), 5 – 7 short answer questions plus 2 longer questions (a short comprehension and a structured question requiring continuous prose)
1 ¼ hours
33.3% of the total AS marks
16.7% of the total A Level marks

Unit 2 BIOL2                                                                         The variety of living organisms
Written examination – (85 marks/140 UMS), 5 – 7 short answer questions plus 2 longer questions involving the handling of data and how science works
1 ¾ hours
46.7% of the total AS marks
23.3% of the total A Level marks
Unit 3 BIO3T                                                    Investigative and practical skills in AS biology
Centre marked route T – 50 marks
Practical skills assessment (6 marks)
Investigative skills assessment (44 marks)
20% of the total AS marks
10% of the total A Level marks

Each student is provided with a textbook to support the course and throughout the year are shown suggested resources that may help their progress through the topics being covered.

For further reading, the specification can be found here.

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