GCSE Biology (8461) Specification

GCSE Biology (8461) Specification

General Information

• For teaching from: September 2016 onwards.
• For exams in: 2018 onwards.
• Version: 1.0, 21 April 2016.
• Up-to-date specification, resources, support, and administration details can be found at aqa.org.uk/8461.

Contents Overview

• Introduction
• Specification at a Glance
• Working Scientifically
• Subject Content
  • Cell Biology
  • Organisation
  • Infection and Response
  • Bioenergetics
  • Homeostasis and Response
  • Inheritance, Variation, and Evolution
  • Ecology
  • Key Ideas
• Scheme of Assessment
• General Administration
• Mathematical Requirements
• Practical Assessment

Introduction

Philosophy

• Science for all abilities and aspirations.
• Clear, straightforward specification and exams.

Specification Development

• Developed with input from over a thousand teachers.
• Subject content is presented clearly, in a logical teaching order.
• Teaching guidance and skills development opportunities are signposted throughout.
• Content and required practicals in GCSE Combined Science: Trilogy are also in GCSE Biology, Chemistry, and Physics.
• Opportunities for progression are provided.

Practicals

• Ten required practicals are clearly laid out in the specification.
• Practicals are open, allowing flexibility in teaching methods.
• Trials have been conducted in schools.
• A practical handbook is available with recommendations and advice from teachers.

Exams

• Use straightforward language and fewer words.
• Have fewer contexts to minimize confusion.
• Increase in difficulty gradually.
• Consistency between content and questions due to collaboration with GCSE Mathematics and A-level science teams.

Resources and Support

• Additional practice papers.
• Schemes of work for Foundation tier students.
• Practical handbook.
• AQA approved textbooks.
• Training courses.
• Subject expertise courses.

Preparing for Exams

• Past papers, mark schemes, and examiners’ reports.
• Specimen papers and mark schemes for new courses.
• Exampro: a searchable bank of past AQA exam questions.
• Exemplar student answers with examiner commentaries.

Enhanced Results Analysis (ERA)

• Free online tool to analyze student results.

Professional Development

• Courses to improve teaching skills and prepare for new roles.

Help and Support

• Website: aqa.org.uk/8461.
• Email: gcsescience@aqa.org.uk.
• Telephone: 01483 477 756.

Specification at a Glance

Linear Qualification

• Students sit all exams at the end of the course.

Subject Content

• Cell biology (Page 16)
• Organisation (Page 24)
• Infection and response (Page 31)
• Bioenergetics (Page 37)
• Homeostasis and response (Page 41)
• Inheritance, variation and evolution (Page 51)
• Ecology (Page 66)
• Key ideas (Page 76)

Assessments

Paper 1

• Topics: Cell biology; Organisation; Infection and response; Bioenergetics.
• Format: Written exam, 1 hour 45 minutes.
• Foundation and Higher Tier available.
• Marks: 100 marks, 50% of GCSE.
• Questions: Multiple choice, structured, closed short answer, and open response.

Paper 2

• Topics: Homeostasis and response; Inheritance, variation and evolution; Ecology.
• Format: Written exam, 1 hour 45 minutes.
• Foundation and Higher Tier available.
• Marks: 100 marks, 50% of GCSE.
• Questions: Multiple choice, structured, closed short answer, and open response.

Working Scientifically

Overview

• Science is a set of ideas about the material world.
• Includes investigating, observing, experimenting, and testing ideas.
• Specification supports building a deep understanding of science.
• Involves talking, reading, and writing about science, as well as doing.
• Represents science mathematically and visually through models.

Development of Scientific Thinking

• WS 1.1 Understand how scientific methods and theories develop over time.
  • Examples: Giving examples of how scientific methods and theories have changed over time. Explaining why new data leads to changes in models or theories. Deciding whether data supports a theory.
• WS 1.2 Use a variety of models to solve problems, make predictions, and develop scientific explanations.
  • Examples: Recognizing/drawing/interpreting diagrams. Translating data to a model. Using models in explanations. Making predictions based on models. Testing models by observation or experiment.
• WS 1.3 Appreciate the power and limitations of science and consider ethical issues.
  • Examples: Explaining why data is needed to answer questions. Outlining ethical arguments about new technologies.
• WS 1.4 Explain everyday and technological applications of science; evaluate implications and make decisions based on evidence.
  • Examples: Describing and explaining technological applications. Evaluating methods to tackle problems caused by human impacts.
• WS 1.5 Evaluate risks in practical science and the wider societal context.
  • Examples: Giving examples of hazards associated with science-based technologies. Explaining why the perception of risk differs from measured risk.
• WS 1.6 Recognize the importance of peer review and communication of results.
  • Examples: Explaining that peer review helps detect false claims. Explaining that popular media reports may be oversimplified, inaccurate, or biased.

Experimental Skills and Strategies

• WS 2.1 Use scientific theories and explanations to develop hypotheses.
  • Example: Suggesting a hypothesis to explain given observations or data.
• WS 2.2 Plan experiments or devise procedures to make observations, test hypotheses, check data, or explore phenomena.
  • Examples: Describing a practical procedure. Explaining why a procedure is well designed. Explaining the need to manipulate and control variables. Identifying independent, dependent, and control variables. Suggesting a procedure for a purpose.
• WS 2.3 Apply knowledge of techniques, instruments, apparatus, and materials to select those appropriate to the experiment.
  • Example: Describing/suggesting/selecting the appropriate technique, instrument, apparatus, or material and explaining why.
• WS 2.4 Carry out experiments appropriately with regard for the correct manipulation of apparatus, accuracy of measurements, and health and safety considerations.
  • Examples: Identifying the main hazards. Suggesting methods to reduce risk of harm.
• WS 2.5 Recognize when to apply knowledge of sampling techniques to ensure representative samples.
  • Example: Suggesting and describing an appropriate sampling technique.
• WS 2.6 Make and record observations and measurements using a range of apparatus and methods.
  • Example: Reading measurements off a scale and recording appropriately.
• WS 2.7 Evaluate methods and suggest possible improvements and further investigations.
  • Examples: Assessing whether sufficient, precise measurements have been taken. Evaluating methods to determine if they are valid.

Analysis and Evaluation

• WS 3.1 Present observations and other data using appropriate methods.
  • Example: Constructing and interpreting frequency tables and diagrams, bar charts, and histograms. Plotting two variables from experimental data.
• WS 3.2 Translate data from one form to another.
  • Example: Translate data between graphical and numeric form.
• WS 3.3 Carry out and represent mathematical and statistical analysis.
  • Examples: Using significant figures, finding arithmetic mean and range, constructing frequency tables, making order of magnitude calculations, changing the subject of an equation, substituting values into equations, determining the slope and intercept of a linear graph, drawing and using the slope of a tangent to a curve, understanding the physical significance of area between a curve and the x-axis.
• WS 3.4 Representing distributions of results and make estimations of uncertainty.
  • Examples: Applying the idea that measurements always have some uncertainty. Using the range of measurements about the mean as a measure of uncertainty.
• WS 3.5 Interpreting observations and other data, including identifying patterns and trends, making inferences, and drawing conclusions.
  • Examples: Using data to make predictions. Recognizing patterns and trends. Drawing conclusions.
• WS 3.6 Present reasoned explanations including relating data to hypotheses.
  • Examples: Commenting on the extent to which data is consistent with a hypothesis. Identifying which hypothesis provides a better explanation of data.
• WS 3.7 Being objective, evaluating data in terms of accuracy, precision, repeatability and reproducibility and identifying potential sources of random and systematic error.
  • Examples: Applying ideas to evaluate data and suggest improvements. Defining accurate, precise, repeatable, and reproducible measurements. Identifying random and systematic errors.
• WS 3.8 Communicating the scientific rationale for investigations, methods used, findings and reasoned conclusions through paper-based and electronic reports and presentations using verbal, diagrammatic, graphical, numerical and symbolic forms.
  • Example: Presenting coherent and logically structured responses, using the ideas in Experimental skills and strategies and Analysis and evaluation, applied to the required practicals, and other practical investigations given appropriate information.

Scientific Vocabulary, Quantities, Units, Symbols, and Nomenclature

• WS 4.1 Use scientific vocabulary, terminology, and definitions.
• WS 4.2 Recognize the importance of scientific quantities and understand how they are determined.
• WS 4.3 Use SI units and IUPAC chemical nomenclature unless inappropriate.
• WS 4.4 Use prefixes and powers of ten for orders of magnitude.
  • Examples: tera, giga, mega, kilo, centi, milli, micro, and nano.
• WS 4.5 Interconvert units.
• WS 4.6 Use an appropriate number of significant figures in calculation.

Subject Content

Format

• Two-column format: specification content (left) and key opportunities for skills development (right).
• WS refers to Working scientifically, MS to Mathematical requirements, and AT to Use of apparatus and techniques.
• Each topic begins with an overview (not directly assessed).
• Content common with GCSE Combined Science: Trilogy, with biology-only content indicated.
• Higher Tier-only content indicated.

Fundamental Biological Concepts and Principles

• Basic understanding of biological principles needed.
• Cell biology: The structure and functioning of cells and how they divide by mitosis and meiosis.
• Variation: Variation occurs when gametes fuse at fertilisation.
• Photosynthesis and Respiration: The two essential reactions for life on Earth.
• Metabolism: Metabolism is the sum of all the reactions happening in a cell or organism.
• Recycling: All molecules are recycled between the living world and the environment to sustain life.

Cell Biology

Overview

• Cells are the basic unit of all forms of life.
• Structural differences between cell types enable them to perform specific functions.
• Genes in the nucleus control these differences.
• Cells divide by mitosis to produce new, identical cells for organism growth.
• Stem cell technology allows doctors to repair damaged organs by growing new tissue from stem cells.

Eukaryotes and Prokaryotes

• Plant and animal cells (eukaryotic) have a cell membrane, cytoplasm, and genetic material enclosed in a nucleus.
• Bacterial cells (prokaryotic) are smaller, with cytoplasm, a cell membrane, and a cell wall, but no nucleus (single DNA loop and plasmids).
• MS 1b, 2a, 2h: Order of magnitude calculations and standard form.
• WS 4.4: Use prefixes centi, milli, micro, and nano.

Animal and Plant Cells

• Main sub-cellular structures, including the nucleus, cell membranes, mitochondria, chloroplasts, and plasmids, are related to their functions.
• Animal cells: Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes.
• Plant cells: Chloroplasts, permanent vacuole filled with cell sap, and a cell wall made of cellulose.
• WS 1.2: Recognise, draw, and interpret images of cells.
• **MS 1d, 3a:
  **Estimations to judge relative size/area of sub-cellular structures.
• AT 7: Use images of cells as comparison for students' own drawings.
  • Required Practical Activity 1: Use a light microscope to observe, draw and label a selection of plant and animal cells. A magnification scale must be included.

Cell Specialisation

• The structure of different cell types relates to their function in a tissue, organ, organ system, or organism.
• Examples: Sperm cells, nerve cells, and muscle cells in animals; root hair cells, xylem, and phloem cells in plants.

Cell Differentiation

• Cells differentiate to form different types of cells.
• Animal cells differentiate early; plant cells retain the ability throughout life.
• Mature animals restrict cell division to repair and replacement.
• As a cell differentiates, it acquires different sub-cellular structures to carry out a certain function.

Microscopy

• Understand how microscopy techniques have developed over time.
• Explain how electron microscopy has increased the understanding of sub-cellular structures (magnification and resolution).
• Electron microscopes have higher magnification and resolving power than light microscopes.
• WS 1.1: Calculations involving magnification, real size, and image size using the formula: magnification = mfrac{size \space of\space image}{size \space of \space real \space object}

Culturing Microorganisms (Biology Only)

• Bacteria multiply by binary fission every 20 minutes if they have nutrients and a suitable temperature.
• Grown in nutrient broth or as colonies on agar gel plates.
• Uncontaminated cultures are needed to investigate disinfectants and antibiotics.
• Calculate the number of bacteria in a population after a certain time given the mean division time.
• MS\space 5c\space Calculate\space cross-sectional \space areas \space of \space colonies \space or \space clear \space areas \space around \space colonies \space using \space πr².
• WS 2.2, 2.4: Aseptic technique is used to prepare an uncontaminated culture.
  • Petri dishes and culture media must be sterilized before use.
  • Inoculating loops must be sterilized by flaming.
  • Petri dish lids should be secured and stored upside down.
  • Cultures should be incubated at 25°C in school laboratories.
• MS 5c: Calculate cross-sectional areas of colonies using \pi r^2.
• MS 1a, 2a, 2h (HT only): Calculate the number of bacteria in a population after a certain time.
  • Express the answer in standard form.
  • Nt = N0 * 2^{(t/g)} where: Nt is the number of bacteria at time t, N0 is the initial number of bacteria, t is the time elapsed, and g is the generation time (mean division time).
• Required Practical Activity 2: Investigate the effect of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibition.

Cell Division

Chromosomes

• The nucleus contains chromosomes made of DNA molecules, each carrying many genes.
• Body cells have pairs of chromosomes.

Mitosis and the Cell Cycle

• Cells divide in stages called the cell cycle.
• Genetic material is doubled and then divided into two identical cells.
• The DNA replicates to form two copies of each chromosome.
• In mitosis, one set of chromosomes is pulled to each end, and the nucleus divides.
• Cytoplasm and cell membranes divide to form two identical cells.
• Mitosis is important for growth and development.
• WS 1.2: Use models to explain how cells divide.

Stem Cells

• A stem cell is an undifferentiated cell capable of giving rise to many more cells of the same type.
• Describe the function of stem cells in embryos, adult animals, and meristems in plants.
• Stem cells from human embryos can be cloned and made to differentiate into different cell types.
• Adult bone marrow stem cells can form blood cells.
• Meristem tissue in plants can differentiate into any plant cell type.
• Treatment with stem cells may help conditions such as diabetes and paralysis.
• In therapeutic cloning, an embryo is produced with the patient's genes.
• Stem cells have potential risks (viral infection) and ethical/religious objections.
• Stem cells from meristems can produce clones of plants quickly and economically.
  • Rare species can be cloned to protect against extinction.
  • Crop plants with special features can be cloned.
• WS 1.3: Evaluate the practical risks and benefits, as well as social and ethical issues, of the use of stem cells in medical research and treatments.

Transport in Cells

Diffusion

• Substances move into and out of cells across membranes via diffusion.
• Diffusion is the spreading out of particles, resulting in net movement from high to low concentration.
• Examples: Oxygen and carbon dioxide in gas exchange, urea from cells to blood.
• Factors affecting diffusion rate: concentration gradient, temperature, surface area of the membrane.
• Single-celled organisms have a large surface area to volume ratio.
• WS 1.2: Use isotonic drinks and high energy drinks in sport.
• WS 1.5: Recognize, draw and interpret diagrams that model diffusion.
• Calculate and compare surface area to volume ratios.
• Effectiveness of an exchange surface is increased by:
  • having a large surface area
  • a membrane that is thin, to provide a short diffusion path
  • (in animals) having an efficient blood supply
  • (in animals, for gaseous exchange) being ventilated.
• MS 1c, 5c: Calculate and compare surface are to volume rations. Compare diffusion of different substances with different properties.

Osmosis

• Water moves across cell membranes via osmosis.
• Osmosis is the diffusion of water from a dilute to a concentrated solution through a partially permeable membrane.
• WS 1.2: Recognise, draw and interpret diagrams that model osmosis.
• MS 1a, 1c: Use simple compound measures of rate of water uptake.
  Plot, Draw, and interpret appropriate graphs
• MS 4a, 4b, 4c, 4d: Use percentages and calculate percentage gain and loss of mass of plant tissue.
• Required Practical Activity 3: Investigate the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue.

Active Transport

• Active transport moves substances against a concentration gradient, requiring energy from respiration.
• Mineral ions are absorbed into plant root hairs from dilute solutions in the soil.
• Sugar molecules are absorbed from lower concentrations in the gut into the blood.
• Describe how substances are transported into and out of cells by diffusion, osmosis, and active transport.
• Explain the differences between the three processes.

Organisation

Principles of Organisation

• Cells are the basic building blocks of all living organisms.
• A tissue is a group of cells with a similar structure and function.
• Organs are aggregations of tissues performing specific functions.
• Organs are organized into organ systems, which work together to form organisms.

Animal Tissues, Organs and Organ Systems

The Human Digestive System

• The digestive system is an organ system in which several organs work together to digest and absorb food.
• Relate knowledge of enzymes to Metabolism.
• Describe the nature of enzyme molecules and relate their activity to temperature and pH changes.
• Digestive enzymes convert food into small soluble molecules that can be absorbed into the bloodstream.
• Carbohydrases break down carbohydrates to simple sugars (Amylase is a carbohydrase which breaks down starch).
• Proteases break down proteins to amino acids.
• Lipases break down lipids (fats) to glycerol and fatty acids.
• Bile is made in the liver and stored in the gall bladder. It is alkaline and emulsifies fat.
• MS 1a, 1c: Students should be able to carry out rate calculations for chemical reactions.
• WS 1.2: Use the ‘lock and key theory’ as a simplified model to explain enzyme action. Students should be able to use other models to explain enzyme action.
  • Required Practical Activity 4: use qualitative reagents to test for a range of carbohydrates, lipids and proteins. To include: Benedict’s test for sugars; iodine test for starch; and Biuret reagent for protein.
  • Required Practical Activity 5: investigate the effect of pH on the rate of reaction of amylase enzyme. Students should use a continuous sampling technique to determine the time taken to completely digest a starch solution at a range of pH values. Iodine reagent is to be used to test for starch every 30 seconds. Temperature must be controlled by use of a water bath or electric heater.

The Heart and Blood Vessels

• The heart is an organ that pumps blood around the body in a double circulatory system.
• The right ventricle pumps blood to the lungs where gas exchange takes place.
• The left ventricle pumps blood around the rest of the body.
• The natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker.
• Artificial pacemakers are electrical devices used to correct irregularities in the heart rate.
• The body contains three different types of blood vessel: arteries, veins, capillaries.
• MS 1a, 1c: Students should be able to use simple compound measures such as rate and carry out rate calculations for blood flow.

Blood

• Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended.
• Know the functions of red blood cells, white blood cells, and platelets.
• Evaluate risks related to use of blood products.
• Be able to recognize different types of blood cells in a photograph or diagram, and explain how they are adapted to their functions.
• AT 7: Observing and drawing blood cells seen under a microscope.
  WS 3.5

Coronary Heart Disease: a Non-Communicable Disease

• Evaluate the advantages and disadvantages of treating cardiovascular diseases by drugs, mechanical devices, or transplant.
• In coronary heart disease, fatty material builds up inside the coronary arteries, narrowing them.
• Stents are used to keep the coronary arteries open.
• Statins are used to reduce blood cholesterol levels.
• Faulty heart valves can be replaced using biological or mechanical valves.
• Artificial hearts are used to keep patients alive while waiting for a heart transplant.
• WS 1.4: Understand the relationship between health and disease and the interactions between different types of disease.

Health Issues

• Health is the state of physical and mental well-being.
• Diseases, both communicable and non-communicable, are major causes of ill health.
• Other factors including diet, stress, and life situations may have a profound effect on both physical and mental health.
• Different types of diseases may interact.
• Understand the principles of sampling as applied to scientific data, including epidemiological data.
• MS 2c, 2g, 4a: Translate disease incidence information between graphical and numerical forms, construct and interpret frequency tables and diagrams, bar charts and histograms, and use a scatter diagram to identify a correlation between two variables.

The Effect of Lifestyle on Some Non-Communicable Diseases

• Discuss the human and financial cost of these non-communicable diseases to an individual, a local community, a nation, or globally.
• Explain the effect of lifestyle factors, including diet, alcohol, and smoking, on the incidence of non-communicable diseases at local, national, and global levels.
• Risk factors:
  • aspects of a person’s lifestyle
  • substances in the person’s body or environment
• A causal mechanism has been proven for some risk factors, but not in others.
• Interpret data about risk factors for specified diseases.
  Understand Scientific data in terms of sampling.
• Translate information between graphical and numerical forms; and extract and interpret information from charts, graphs and tables in terms of risk factors.
• Use a scatter diagram to identify a correlation between two variables in terms of risk factors

Cancer

• Describe cancer as the result of changes in cells that lead to uncontrolled growth and division.
• Benign tumours are growths of abnormal cells which are contained in one area, usually within a membrane.
• Malignant tumour cells are cancers. They invade neighboring tissues and spread to different parts of the body, forming secondary tumours.
• Scientists have identified lifestyle risk factors for various types of cancer. There are also genetic risk factors for some cancers.

Plant Tissues, Organs and Systems

Plant Tissues

• Explain how the structures of plant tissues are related to their functions.
• Plant tissues include: epidermal tissues, palisade mesophyll, spongy mesophyll, xylem and phloem, meristem tissue.
• The leaf is a plant organ (epidermis, palisade and spongy mesophyll, xylem and phloem, and guard cells surrounding stomata).

Plant Organ System

• Explain how the structure of root hair cells, xylem, and phloem are adapted to their functions.
• Explain the effect of changing temperature, humidity, air movement, and light intensity on the rate of transpiration.
  Measure the rate of transpiration by the uptake of water.
  Investigate the distribution of stomata and guard cells.
• Describe the process of transpiration and translocation, including the structure and function of the stomata.
• Root hair cells are adapted for the efficient uptake of water by osmosis, and mineral ions by active transport.
• Detailed pholem not required.
  Process data from investigations involving stomata and transpiration rates to find arithmetic means, understand the principles of sampling and calculate surface areas and volumes.