Y13: A2 Biology

Biol A2

In year 13 we follow the AQA Biology specification. The course consists of 3 units which are assessed at the end of the year.

Unit 4 – Populations and environment

This unit consists of the following sections and is assessed by a 1 hr 30 min examination.

The dynamic equilibrium of populations is affected by a number of factors
Populations and ecosystems
Investigating populations
Variation in population size
Human populations

ATP provides the immediate source of energy for biological processes

In photosynthesis, energy is transferred to ATP in the light-dependent reaction and the ATP is utilised in the light-independent reaction
Light-dependent reaction
Light-independent reaction
Limiting factors

In respiration, glycolysis takes place in the cytoplasm and the remaining steps in the mitochondria. ATP synthesis is associated with the electron transfer chain in the membranes of mitochondria
Aerobic respiration
Anaerobic respiration

Energy is transferred through ecosystems and the efficiency of transfer can be measured
Energy transfer
Energy and food production

Chemical elements are recycled in ecosystems. Microorganisms play a key role in recycling these elements
Nutrient cycles

Ecosystems are dynamic systems, usually moving from colonisation to climax communities in the process of succession

Genetic variation within a species and geographical isolation lead to the accumulation of different genetic information in populations and the potential formation of new species
The Hardy-Weinberg principle


Unit 5 – Control in cells and in organisms

This unit consists of the following sections and is assessed by a 2 hr 15 min examination.

Stimuli, both internal and external, are detected and lead to a response
Survival and response
Control of heart rate

Coordination may be chemical or electrical in nature
Nerve impulses
Synaptic transmission

Skeletal muscles are stimulated to contract by nerves and act as effectors
The sliding filament theory of contraction
Muscles as effectors

Homeostasis is the maintenance of a constant internal environment
Temperature control
Control of blood glucose concentration

Negative feedback helps maintain an optimal internal state in the context of a dynamic equilibrium. Positive feedback also occurs
Control of mammalian oestrus

The sequence of bases in DNA determines the structure of proteins, including enzymes
The genetic code
Polypeptide synthesis
Gene mutation

Gene expression is controlled by a number of features
Most of a cell’s DNA is not translated
Regulation of transcription and translation

Gene cloning technologies allow study and alteration of gene function in order to better understand organism function and to design new industrial and medical processes
Gene cloning and transfer
Gene therapy
Medical diagnosis
Genetic fingerprinting


Unit 6 – Investigative and practical skills in A2 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 4 BIOL4                                                                                Populations and environment
Written examination – (75 marks/100 UMS), 6 – 9 short answer questions plus 2 longer questions involving continuous prose and how science works
1 ½ hours
16.7% of the total A Level marks
Unit 5 BIOL5                                                                        Control in cells and in organisms
Written examination – (100 marks/140 UMS), 8 – 10 short answer questions plus 2 longer questions (a data handling question and a synoptic essay – choice of 1 of 2)
2 ¼ hours
23.3% of the total A Level marks

Unit 6 PHA6T                                                    Investigative and practical skills in A2 biology
Centre marked route T – 50 marks
Practical skills assessment (6 marks)
Investigative skills assessment (44 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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