GCE AS Level Biology Unit 2 notes for AQA

GCE AS Level Biology notes written for the AQA specification Biology (2410).

The topics covered in the revision guide are detailed here:

Unit 2
3.2.1 Living organisms vary and this variation is influenced by genetic and environmental factors. Investigating variation
Causes of variation
3.2.2 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
Meiosis
3.2.3 Similarities and differences in DNA result in genetic diversity. Genetic diversity
3.2.4 The variety of life is extensive and this is reflected in similarities and differences in its biochemical basis and cellular organisation. Haemoglobin
Carbohydrates
Cells
3.2.5 During the cell cycle, genetic information is copied and passed to genetically identical daughter cells. Replication of DNA
Mitosis
Cell cycle
3.2.6 In complex multicellular organisms, cells are organised into tissues, tissues into organs and organs into systems. Cell differentiation
3.2.7 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
3.2.8 Classification is a means of organising the variety of life based on relationships between organisms and is built round the concept of species. Principles of taxonomy
3.2.9 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
DNA
Proteins
Behaviour
3.2.10 Adaptation and selection are major components of evolution and make a significant contribution to the diversity of living organisms. Antibiotics
Genetic variation in bacteria
3.2.11 Biodiversity may be measured within a habitat. Species diversity
Index of diversity