A Level Biology

What shares the same basic chemistry and provides evidence for evolution? The answer is ALL life on Earth. Organisms are diverse, however their cells are built from similar carbon-based compounds and these compounds function in similar ways. They contain carbohydrates which are used as energy sources, Lipids that act as hormones and store energy, Proteins that work as enzymes and nucleic acids which store genetic information. For this topic, you will cover:

• Monomers and polymers
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
• ATP
• Water
• Inorganic ions

All life on earth is made of cells which share similar features. All cells have a cell-surface membrane, however eukaryotic cells also have internal membranes such as the nucleus and mitochondria. New cells arise from existing cells by binary fission in bacteria or mitosis and meiosis. Cells have proteins which control transport and act as antigens. This helps build up immunity against future infections. For this topic, you will cover:

• Cell structure
• All cells arise from other cells
• Transport across cell membranes
• Cell recognition and the immune system

Oxygen, glucose and waste products move between the outside environment and the inside of the body through exchange surfaces. To enter or leave cells, substances must cross cell membranes. Most cells are surrounded by tissue fluid and therefore diffusion alone can be too slow to carry substances. Mass transport systems therefore carry substances quickly between exchange surfaces and cells. For this topic, you will cover:

• Surface area to volume ratio
• Gas exchange
• Digestion and absorption
• Mass transport

Biodiversity is the variety of life and includes different species such as plants, animals and bacteria. It also covers the differences between individuals of the same species. For example height or eye colour and the different types of cells in one organism. Differences occur because of genes. Genes are small sections of DNA that provide instructions for making proteins. Differences help organisms survive in their environment. For this topic, you will cover:

• DNA, genes and chromosomes
• DNA and protein synthesis
• Genetic diversity can arise as a result of mutation or during meiosis
• Genetic diversity and adaption
• Species and taxonomy
• Biodiversity within a community
• Investigating diversity

ATP is the energy carrying molecule used in cells. It can release energy very quickly. In photosynthesis, light energy is absorbed and used to produce ATP whereas in respiration, organisms break down substances to release energy and make ATP. Photosynthesis happens in plants, algae and some bacteria. Respiration happens in all living organisms. For this topic, you will cover:

• Photosynthesis
• Respiration
• Energy and ecosystems
• Nutrient cycles

Organisms have a response system like a message being sent and actioned. This involves stimulus, receptors, coordinators and effectors. Nerves send fast messages which are quick and short. Hormones are slower responses as they travel in the blood but last longer. Plants use hormone-like chemicals to control growth. For this topic, you will cover:

• Stimuli, both internal and external, are detected and lead to a response
• Nervous coordination
• Skeletal muscles are stimulated to contract by nerves and act as effectors
• Homeostasis is the maintenance of a stable internal environment

Individuals within a species can have the same genes, however, they will have different alleles, inherited from their parents, which causes variation. Populations change over time due to natural selection and this is known as evolution. For this topic, you will cover:

• Inheritance
• Populations
• Evolution may lead to speciation
• Populations in ecosystems

Each cell within your body has the same DNA and therefore the same genetic information, however they only use some of their genes. For example, a muscle cell uses genes for movement which is known as gene expression – turning genes on or off. Gene activity is affected by things such as hormones, diet or stress. When gene control goes wrong, diseases can occur. This helps scientists to diagnose and treat illnesses. For this topic, you will cover:

• Alteration of the sequence of bases in DNA can alter the structure of proteins
• Gene expression is controlled by a number of features
• Using genome projects
• The study and alteration of gene function and understanding of organism function and the design of new industrial and medical processes.

• Monomers and polymers
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
• ATP
• Water
• Inorganic ions

• Cell structure
• All cells arise from other cells
• Transport across cell membranes
• Cell recognition and the immune system

• Surface area to volume ratio
• Gas exchange
• Digestion and absorption
• Mass transport

• DNA, genes and chromosomes
• DNA and protein synthesis
• Genetic diversity can arise as a result of mutation or during meiosis
• Genetic diversity and adaption
• Species and taxonomy
• Biodiversity within a community
• Investigating diversity

Cells are the basic units of all living organisms. The structure of a cell explains how living things are built and how they function. Each cell carries out processes such as respiration, growth and reproduction. A microscope allows scientists to observe cells and modern electron microscopes show a cell in more detail such as its structure.

• The microscope in cell studies
• Cells as the basic units of living organisms

Biological molecules consist of carbohydrates, lipids, proteins and water. These chemicals allow cells to function properly. We can use food tests to identify these molecules such as Benedict’s test for reducing sugars, Biuret test for proteins and the ethanol emulsion test for lipids.

• Testing for biological molecules
• Carbohydrates and lipids
• Proteins and water

Enzymes speed up chemical reactions in living cells. They are made of protein and each enzyme has a specific shape with an active site that fits only one particular substrate. Factors that affect enzyme action include temperature, pH and substrate concentration.

• Mode of action of enzymes
• Factors that affect enzyme action

Cell membranes help maintain a stable environment by controlling what enters and leaves the cell. Substances move into and out of cells in various ways. Oxygen can pass through the membrane by diffusion. Water moves by osmosis and larger or charged molecules may require facilitated diffusion. These transport processes allow cells to take in nutrients, remove waste and maintain stability.

• Fluid mosaic membranes
• Movement of substances into and out of cells

Replication and division of nuclei and cells is essential for growth, repair and asexual reproduction. Mitosis has several stages and the behaviour of chromosomes during mitosis ensures that each new cell received the same number and type of chromosomes as the original cell.

• Replication and division of nuclei and cells
• Chromosome behaviour in mitosis

DNA is a nucleic acid that stores and transfers genetic information. The information in DNA is used to make proteins and this process is known as protein synthesis. The process ensures that the genetic code in DNA is expressed as functional proteins that control cell structure and activities.

• Structure and replication of DNA
• Protein synthesis

In order for plants to grow and survive, they require water, minerals and sugars. This topic will cover the two main transport tissues: xylem and phloem. You will gain an understanding of how nutrients are distributed throughout the plant.

• Structure of transport tissues
• Transport mechanisms

The circulatory system moves oxygen, nutrients, hormones and waste around the body. For mammals, blood passes through the heart twice to complete one full circuit. This is known as a double circulatory system. The heart acts as a pump to keep the blood flowing. Valves ensure bloods flows in the correct direction and the cardiac cycle maintains a continuous blood supply to tissues.

• The circulatory system
• The heart

During gas exchange, oxygen will enter the body and carbon dioxide will leave it. Smoking damages the gas exchange in multiple ways. For example, Tar damages the cilia lining the airways leading to mucus build-up. This increases the risk of infections such as bronchitis. Over time, smoking can increase the risk of lung cancer, heart disease and chronic respiratory conditions.

• The gas exchange system
• Smoking

Bacteria, viruses and parasites are microorganisms that can be passed from one organism to another. These microorganisms cause infectious diseases such as influenza, tuberculosis and malaria.

Antibiotics are drugs that help treat bacterial infections by killing the bacteria or stopping their growth. Antibiotics aren’t effective against viruses which means they would not help someone with influenza or the common cold.

• Infectious disease
• Antibiotics

The body’s immune system is made up of white blood cells, tissues and microorganisms. These all destroy invaders. When the body has to fight an infection it will also provide long-term protection by creating memory cells. These remember the pathogen for faster response if it appears again in the future. Antibodies are important for immunity but vaccinations are also used too.

• The immune system
• Antibodies and vaccination

Cells gain energy from food which essential for all living organisms. Cells release energy from food molecules which is known as respiration.

• Energy
• Respiration

During photosynthesis, plants convert energy from light into chemical energy which is stored in glucose. Photosynthesis is limited by various factors such as light, carbon dioxide and temperature. Plants are adapted to maximise photosynthesis. For example, some plants have thin leaves to reduce the diffusion distance for carbon dioxide and water. This ensures efficient energy conversion.

• Photosynthesis as an energy transfer process
• Investigation of limiting factors
• Adaptations for photosynthesis

Mammals are able to regulate factors such as body temperature, blood glucose levels and water balance. Plants also regulate water levels, temperature and gas exchange. This is known as homeostasis.

• Homeostasis in mammals
• Homeostasis in plants

Control and co-ordination helps both mammals and plants survive and will keep their bodies or structures working properly.

• Control and co-ordination in mammals
• Control and co-ordination in plants

Inherited change helps us to understand how characteristics are passed down from parents to their offspring. Eye colour, hair type or height are contained within instructions for each gene. Genes not only determine characteristics but they also lead to new characteristics or variations through mutations or changes.

• Passage of information from parent to offspring
• The roles of genes in determining the phenotype
• Gene control

Variation, selection and inheritance drive the diversity of life we see today.

• Variation
• Natural and artificial selection
• Evolution

This topic is all about protecting life on Earth. Biodiversity, classification and conservation helps us to understand life on earth and ensures it continues for future generations.

• Biodiversity
• Classification
• Conservation

Genetic technology allows us to understand and use genes in ways that improve health, food and science.

• Principles of genetic technology
• Genetic technology applied to medicine
• Genetically modified organisms in agriculture

This topic will look at what the body is made of such as carbohydrates, lipids and proteins. It will also show how substances are transported around the body and how lifestyle factors influence health.

1A.1 The chemistry of life 1A.2 Carbohydrates 1: Monosaccharides and disaccharides 1A.3 Carbohydrates 2: Polysaccharides 1A.4 Lipids 1A.5 Proteins

1B.1 The principles of circulation 1B.2 The roles of the blood 1B.3 Circulation in the blood vessels 1B.4 The mammalian heart 1B.5 Atherosclerosis

1C.1 Risk, correlation and cause 1C.2 Investigating the causes of CVDs 1C.3 Risk factors for cardiovascular disease 1C.4 Diet and cardiovascular health 1C.5 Dietary antioxidants and cardiovascular disease 1C.6 Using the evidence 1C.7 The benefits and risks of treatment

This topic will explain how cells control movement of substances, how chemical reactions are controlled through enzymes and how DNA stores information and determines inherited traits through genetics.

2A.1 Cell membranes 2A.2 Cell transport and diffusion 2A.3 Osmosis: A special case of diffusion 2A.4 Active transport 2A.5 The need for gas exchange surfaces 2A.6 The mammalian gas exchange system

2B.1 Enzymes 2B.2 How enzymes work 2B.3 The structure of DNA and RNA 2B.4 How DNA works 2B.5 The genetic code 2B.6 DNA and protein synthesis

2C.1 Gene mutation 2C.2 Patterns of inheritance 2C.3 Sex linkage 2C.4 Cystic fibrosis: A genetic disease 2C.5 Genetic screening

This topic is all about cells. It will help you gain an understanding of how cells are structured and organised. You will find out how cells divide through mitosis and meiosis and how fertilisation leads to a new organism. Finally, you will see how cells specialise through gene expression and how stem cells may be used in medicine.

3A.1 Observing cells 3A.2 Eukaryotic cells 1: Common cellular structures 3A.3 Eukaryotic cells 2: Protein transport 3A.4 Prokaryotic cells 3A.5 The organisation of cells

3B.1 The cell cycle 3B.2 Mitosis 3B.3 Sexual reproduction and meiosis 3B.4 Gametes: Structure and function 3B.5 Fertilisation in mammals and plants

3C.1 Cell differentiation 3C.2 Interactions between genes and the environment 3C.3 Controlling gene expression 3C.4 Stem cells 3C.5 Using stem cells

This topic will cover three major themes. Plant biology which will help you understand how plant cells and structures work. Classification which tells us how scientists organise living organisms. Finally, Biodiversity and conservation which shows how species evolve and how ecosystems are protected.

4A.1 The cell wall 4A.2 Plant organelles 4A.3 Plant stems 4A.4 The importance of water and minerals in plants 4A.5 Using plant starch and fibres 4A.6 Plant-based medicines 4A.7 Developing new drugs

4B.1 Principles of classification 4B.2 What is a species? 4B.3 Domains, kingdoms or both?

4C.1 Biodiversity and endemism 4C.2 Measuring biodiversity 4C.3 Adaptation to a niche 4C.4 Gene pool and genetic diversity 4C.5 Reproductive isolation and speciation 4C.6 Conservation: Why and how?

This topic will provide an insight into how plants capture energy from sunlight through photosynthesis. You will also gain an understanding of how energy moves through food chains and ecosystems. Finally, you will study how human activity affects the environment.

5A: Photosynthesis 5B: Ecology 5C: Environment and climate change

This topic will explore microbes and their characteristics along with the immune system and how it fights infection. You will discover how decomposition works and how forensic biology uses microorganisms to solve crimes.

6A: Microbiology 6B: Immunity 6C: Decomposition and forensics

This topic will look into how cells release energy, how muscles generate movement and how the body maintains stable internal conditions.

7A: Cellular respiration 7B: Muscles, movement and the heart 7C: Control of the internal environment

This topic will explore how organisms detect and respond to changes within their environment. It will look at how signals are transmitted in the body and how modern genetics is applied in biotechnology.

8A: The nervous system and neurones 8B: Coordination in animals and plants 8C: Gene technology