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Revision summary help for the AQA GCSE 9-1 Combined Science Trilogy biology 1 exam paper - learning objectives for exam paper (re-edit) AQA GCSE science 8464/B/1F and 8464/B/1H 2020 examination paper onwards AQA Grade 9-1 GCSE Combined Science Trilogy 8464 Biology Paper 1 1F 1H papers - AQA GCSE Combined Science TRILOGY biology paper 1 Topic 1 "Cell biology", Topic 2 "Organisation", Topic 3 "Infection and response", Topic 4 "Bioenergetics" LINK for AQA GCSE Combined Science Trilogy Biology Paper 2 LINK for AQA GCSE BIOLOGY 1 Paper 1 LINK for AQA GCSE BIOLOGY 2 Paper 2 This is a BIG website, you need to take time to explore it [SEARCH BOX] Use your mobile phone in 'landscape' orientation? email doc brown - query? or comment? For ALL other exam papers, use and bookmark the link below PLEASE READ CAREFULLY THE FOLLOWING POINTS before using my AQA 9-1 GCSE science pages
Syllabus-specification CONTENT INDEX of revision summary notes (revision study notes for AQA gcse combined science biology) Revision summaries for AQA 9-1 GCSE Combined Science: Trilogy Biology Paper 1 What's assessed in this paper? Topics 1-4 (THIS PAGE) (revision study notes for AQA gcse combined science biology) SUMMARY of Topic 1. Cell biology (AQA 9-1 GCSE Combined Science Trilogy Biology Paper 1) SUMMARY of Topic 2. Organisation (AQA 9-1 GCSE Combined Science Trilogy Biology Paper 1) Topic 2.1 Principles of organisation - Organisational hierarchy Topic 2.2 Animal tissues, organs and organ systems Topic 2.3 Plant tissues, organs and systems SUMMARY of Topic 3. Infection and response (AQA 9-1 GCSE Comb. Sci. Trilogy Biology Paper 1) Topic 3.1 Communicable diseases SUMMARY of Topic 4. Bioenergetics (AQA 9-1 GCSE Combined Science Trilogy Biology Paper 1)
Revision summaries for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 2 What's assessed in this paper? Topics 5-7 (on a separate page) (revision study notes for AQA gcse combined science biology) SUMMARY of Topic 5. Homeostasis and response (AQA GCSE Combined Science Trilogy Biology Paper 2) SUMMARY of Topic 7. Ecology (AQA 9-1 GCSE Combined Science Trilogy Biology Paper 2) SUBJECT CONTENT of the AQA science syllabus-specifications biology part of 8464 Fundamental biological concepts and principles needed for BOTH biology papers You should have a basic understanding of the following biological principles and be able to apply them in either paper: Key ideas in biology:
The structure and functioning of cells and how they divide by mitosis and meiosis from sections Cell biology and Meiosis. That variation occurs when gametes fuse at fertilisation from section Sexual and asexual reproduction. The two essential reactions for life on Earth: photosynthesis and respiration from sections Photosynthetic reaction and Aerobic and anaerobic respiration. Metabolism is the sum of all the reactions happening in a cell or organism, in which molecules are made or broken down from section Metabolism. All molecules are recycled between the living world and the environment to sustain life from section How materials are cycled. You should be able to recall and use this knowledge in questions that link different areas of the specification to develop coherent arguments and explanations.
TOPICS for AQA GCSE Combined Science Trilogy: Biology Paper 1 (revision study notes for AQA gcse combined science biology) Topic 1 Cell biology (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 1 "Cell biology") Know that cells are the basic unit of all forms of life and you should know how structural differences between types of cells enables them to perform specific functions within the organism. These differences in cells are controlled by genes in the nucleus. For an organism to grow, cells must divide by mitosis producing two new identical cells. Know that if cells are isolated at an early stage of growth before they have become too specialised, they can retain their ability to grow into a range of different types of cells. This phenomenon has led to the development of stem cell technology. This is a new branch of medicine that allows doctors to repair damaged organs by growing new tissue from stem cells. Topic 1.1 Cell structure (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 1 "Cell biology") 1.1.1 Eukaryotes and prokaryotes (revision study notes for AQA gcse combined science biology) Know that plant and animal cells (eukaryotic cells) have a cell membrane, cytoplasm and genetic material enclosed in a nucleus. Know that bacterial cells (prokaryotic cells) are much smaller and simpler in comparison. They have cytoplasm and a cell membrane surrounded by a cell wall. The genetic material is not enclosed in a nucleus. It is a single DNA loop and there may be one or more small rings of DNA called plasmids. Be able to use prefixes centi, milli, micro and nano and you must be able to demonstrate an understanding of the scale and size of cells and be able to make order of magnitude calculations including the use of standard form. Introduction to plant and animal cell structure and function Microscopy - the development and use of microscopes in biology 1.1.2 Animal and plant cells (revision study notes for AQA gcse combined science biology) You should be able to explain how the main sub-cellular structures, including the nucleus, cell membranes, mitochondria, chloroplasts in plant cells and plasmids in bacterial cells are related to their functions. Most animal cells have the following parts:
In addition to the parts found in animal cells (listed above), plant cells often have:
Plant and algal cells also have a cell wall made of cellulose, which strengthens the cell. You should be able to use estimations and explain what they should be used to judge the relative size or area of sub-cellular structures.
Introduction to plant and animal cell structure and function Microscopy - the development and use of microscopes in biology Photosynthesis, importance explained, limiting factors affecting rate Plant cells - transport, gas exchange, transpiration & experiments 1.1.3 Cell specialisation (revision study notes for AQA gcse combined science biology) You should be able to, when provided with appropriate information, explain how the structure of different types of cell relate to their function in a tissue, an organ or organ system, or the whole organism. Know that cells may be specialised to carry out a particular function e.g.
Introduction to plant and animal cell structure and function An introduction to cell specialisation An introduction to the nervous system including the reflex arc 1.1.4 Cell differentiation (revision study notes for AQA gcse combined science biology) Know that as an organism develops, cells differentiate to form different types of cells.
In mature animals, cell division is mainly restricted to repair and replacement. As a cell differentiates it acquires different sub-cellular structures to enable it to carry out a certain function. It has become a specialised cell. Introduction to plant and animal cell structure and function - comparison of subcellular structures Stem cells and an introduction to cell specialisation 1.1.5 Microscopy (revision study notes for AQA gcse combined science biology) You should be able to:
Know and understand that an electron microscope has much higher magnification and resolving power than a light microscope. This means that it can be used to study cells in much finer detail. This has enabled biologists to see and understand many more sub-cellular structures. You should appreciate the differences in magnification and resolution between a light microscope and an electron microscope. Be able to explain how electron microscopy has increased understanding of subcellular structures. Be able to use prefixes centi (10-2), milli (10-3), micro (10-6) and nano (10-9) (expressing answers in standard form) and carry out calculations involving magnification, real size and image size using the formula:
With light microscopes you can see individual cells and large subcellular structures like the nucleus. With electron microscopes, using a beam of electrons instead of a beam of light, you gain a much higher resolution seeing much smaller objects e.g. the structures of mitochondria, chloroplasts, ribosomes and plasmids. Microscopy - the development and use of microscopes in biology gcse biology revision notes Introduction to plant and animal cell structure and function - comparison of subcellular structures
Topic 1.2 Cell division (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 1 "Cell biology") 1.2.1 Chromosomes (revision study notes for AQA gcse combined science biology) Know that the nucleus of a cell contains chromosomes made of coiled DNA molecules, they are the genetic information. Each chromosome carries a large number of genes. In body cells the chromosomes are normally found in pairs. Be able to use models and analogies to develop explanations of how cells divide. CELL DIVISION - cell cycle - mitosis and meiosis in sexual reproduction DNA and RNA structure and Protein Synthesis and an experiment to extract DNA 1.2.2 Mitosis and the cell cycle (revision study notes for AQA gcse combined science biology) Know that cells divide in a series of stages called the cell cycle and you need to be able to describe the stages of the cell cycle including mitosis. One of these stages is mitosis where the DNA, which has already been copied, divides. During the cell cycle the genetic material is doubled and then divided into two identical cells. (1) Before a cell can divide it needs to grow and increase the number of sub-cellular structures such as ribosomes and mitochondria. (2) The DNA replicates to form two copies of each chromosome. In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides. (3) Finally the cytoplasm and cell membranes divide to form two identical cells. You need to understand the three overall stages of the cell cycle but do not need to know the different phases of the mitosis stage. Cell division by mitosis is important in the growth and development of multicellular organisms. You should be able to recognise and describe situations in given contexts where mitosis is occurring. CELL DIVISION - cell cycle - mitosis and meiosis in sexual reproduction 1.2.3 Stem cells (revision study notes for AQA gcse combined science biology) Know that a stem cell is an undifferentiated cell of an organism which is capable of giving rise to many more cells of the same type, and from which certain other cells can arise from differentiation.
Stem cells from human embryos can be cloned and made to differentiate into most different types of human cells.
Know that meristem tissue in plants can differentiate into any type of plant cell, throughout the life of the plant.
Treatment with stem cells may be able to help conditions such as diabetes and paralysis. In therapeutic cloning an embryo is produced with the same genes as the patient. Stem cells from the embryo are not rejected by the patient’s body so they may be used for medical treatment. The use of stem cells has potential risks such as transfer of viral infection, and some people have ethical or religious objections against research and application of stem cells. Stem cells from meristems in plants can be used to produce clones (genetically identical cells) of plants quickly and economically.
Be able to evaluate the practical risks and benefits, as well as social and ethical issues, of the use of stem cells in medical research and treatments. Stem cells and an introduction to cell specialisation See also sections on Cloning - tissue culture of plants and animals
Topic 1.3 Transport in cells (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 1 "Cell biology") 1.3.1 Diffusion (revision study notes for AQA gcse combined science biology) Know that substances may move into and out of cells across the cell membranes via diffusion. Diffusion is the spreading of the particles of any substance in solution, or particles of a gas, resulting in a net movement from an area of higher concentration to an area of lower concentration.
Organisms must exchange substances with their environment i.e. take in nutrients or remove waste products. Some of the substances transported in and out of cells by diffusion are oxygen and carbon dioxide in gas exchange, and of the waste product urea from cells into the blood plasma for excretion in the kidney. Appreciate that large molecules cannot pass through the membrane. You should be able to explain how different factors affect the rate of diffusion, factors which affect the rate of diffusion are:
A single-celled organism has a relatively large surface area to volume ratio. This allows sufficient transport of molecules into and out of the cell to meet the needs of the organism. You should be able to calculate and compare surface area to volume ratios. You should be able to explain the need for exchange surfaces and a transport system in multicellular organisms in terms of surface area to volume ratio. You should be able to explain how the small intestine and lungs in mammals, gills in fish, and the roots and leaves in plants, are adapted for exchanging materials. In multicellular organisms the smaller surface area to volume ratio means surfaces and organ systems are specialised for exchanging materials. This is to allow sufficient molecules to be transported into and out of cells for the organism’s needs. The effectiveness of an exchange surface is increased by:
Be able to calculate and compare surface area to volume ratios. You should understand the use of isotonic drinks and high energy drinks in sport. Diffusion, osmosis and active transport Examples of surfaces for the exchange of substances in animal organisms 1.3.2 Osmosis (revision study notes for AQA gcse combined science biology) Know that water may move across cell membranes via osmosis. Osmosis is the diffusion of water from a dilute solution to a concentrated solution through a partially permeable membrane. Revise the investigation into the effect of a range of concentrations of salt or sugar solutions on the mass of plant tissue. Be able to recognise, draw and interpret diagrams that model osmosis. You should be able to:
You should be able to plot, draw and interpret appropriate graphs relevant to osmosis. Diffusion, osmosis and active transport 1.3.3 Active transport (revision study notes for AQA gcse combined science biology) You should understand that active transport moves substances from a more dilute solution to a more concentrated solution (against a concentration gradient). This requires energy from respiration. Without active transport, sufficient food for the organism may not be absorbed from the gut. You should be able to link the structure of a root hair cell to its function. Active transport allows mineral ions to be absorbed into plant root hairs from very dilute solutions in the soil. Plants require ions for healthy growth. It also allows sugar molecules to be absorbed from lower concentrations in the gut into the blood which has a higher sugar concentration. Sugar molecules are used for cell respiration. You should be able to explain and describe how diffusion, osmosis and active transport are used to transport materials in and out of cells and the differences between these three processes. In terms of exchanging substances at various interfaces you should know all about gas exchange in the lungs, the function of villi in the small intestine, leaf structure and gas exchange and gills of fish enable an efficient gas exchange. Diffusion, osmosis and active transport Transport and gas exchange in plants, absorption of nutrients
Topic 2 Organisation (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 2 "Organisation") Know that the human digestive system which provides the body with nutrients and the respiratory system that provides it with oxygen and removes carbon dioxide. These gases are dissolved materials that need to be moved quickly around the body in the blood by the circulatory system. Know that damage to any of these systems can be debilitating if not fatal. Although there has been huge progress in surgical techniques, especially with regard to coronary heart disease, many interventions would not be necessary if individuals reduced their risks through improved diet and lifestyle. Know how a plant’s transport system is dependent on environmental conditions to ensure that leaf cells are provided with the water and carbon dioxide that they need for photosynthesis. Topic 2.1 Principles of organisation - Organisational hierarchy (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 2 "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 organised into organ systems, which work together to form organisms. You should be able to develop an understanding of size and scale in relation to cells, tissues, organs and systems. Topic 2.2 Animal tissues, organs and organ systems (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 2 "Organisation") 2.2.1 The human digestive system (revision study notes for AQA gcse combined science biology) This section does assumes knowledge of the digestive system studied in Key Stage 3 science. The digestive system is an example of an organ system in which several organs work together to digest and absorb food. Introduction to the organisation of cells => tissues => organs => organ systems (e.g. in humans) You should be able to relate the action of enzymes to metabolism. You should be able to describe the nature of enzyme molecules and relate their activity to temperature and pH changes. You should be able to carry out rate calculations for chemical reactions. (rates of reaction notes gcse chemistry notes)
Know that enzymes catalyse specific reactions in living organisms due to the specific shape of their active site. Enzymes:
ENZYMES - structure, function, optimum conditions, investigation experiments See also Enzymes and Biotechnology (gcse chemistry notes) You should be able to recall the sites of production and the action of the enzymes amylase, proteases and lipases. You should be able to understand simple word equations but no chemical symbol equations are required.
Know that the products of digestion are used to build new carbohydrates, lipids and proteins.
You should have used qualitative reagents to identify biological molecules such as starch, sugars and proteins (know the chemical tests for them). Bile is made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase. Also revise (1) The use qualitative reagents to test for a range of foods e.g. carbohydrates, lipids and proteins - including Benedict’s test for sugars; iodine test for starch; and Biuret reagent for protein. and (2) the investigation into the effect of a factor on the rate of an enzyme-controlled reaction (it could be concentration, temperature or pH) - investigation of the effect of pH on the rate of reaction of amylase enzyme. You should have investigated the effect of pH on the rate of reaction of amylase enzyme by using 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. See also Enzymes - section on digestion and synthesis Food tests for reducing sugars, starch, proteins and lipids
2.2.2 The heart and blood vessels (revision study notes for AQA gcse combined science biology) You should know the structure and functioning of the human heart and lungs, including how lungs are adapted for gaseous exchange. 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.
Knowledge of the lungs is restricted to the trachea, bronchi, alveoli and the capillary network surrounding the alveoli. Know that the natural resting heart rate is controlled by a group of cells located in the right atrium that act as a pacemaker.
The body contains three different types of blood vessel: arteries, veins and capillaries.
Introduction to plant and animal cell structure and function - comparison of subcellular structures
2.2.3 Blood (revision study notes for AQA gcse combined science biology) Blood is a tissue consisting of plasma, in which the red blood cells, white blood cells and platelets are suspended and know the function of each component.
Introduction to plant and animal cell structure and function - comparison of subcellular structures 2.2.4 Coronary heart disease: a non-communicable disease (revision study notes for AQA gcse combined science biology) You should be able to evaluate the advantages and disadvantages of treating cardiovascular diseases by drugs, mechanical devices or transplant.
In coronary heart disease (an example of cardiovascular disease) layers of fatty material build up inside the coronary arteries, narrowing them. This reduces the flow of blood through the coronary arteries, resulting in a lack of oxygen for the heart muscle. Inserted stents are used to keep the coronary arteries open. Statins are widely used to reduce blood cholesterol levels which slows down the rate of fatty material deposit. In some people heart valves may become faulty, preventing the valve from opening fully, or the heart valve might develop a leak. You should understand the consequences of faulty valves. Faulty heart valves can be replaced using biological or mechanical valves. In the case of heart failure a donor heart, or heart and lungs can be transplanted. Artificial hearts are occasionally used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery. Keeping healthy - non-communicable diseases - risk factors for e.g. heart disease Respiration - aerobic and anaerobic Keeping healthy - diet and exercise
2.2.5 Health issues (revision study notes for AQA gcse combined science biology) You should be able to describe the relationship between health and disease and the interactions between different types of disease. Health is the state of physical and mental wellbeing. Diseases, both communicable diseases 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 disease may interact e.g.
Be able to translate disease information between graph 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. You also need to understand the principles of sampling as applied to scientific data, including epidemiological data. Keeping healthy - communicable diseases - pathogen infections including viruses and vaccination Keeping healthy - non-communicable diseases - risk factors for e.g. CVD, cancers gcse biology revision notes Keeping healthy - diet and exercise 2.2.6 The effect of lifestyle on some non-communicable diseases (revision study notes for AQA gcse combined science biology) You should recall that many noncommunicable diseases are caused by the interaction of a number of factors (to include cardiovascular disease, some lung and liver diseases and diseases influenced by nutrition, including Type 2 diabetes). Be able to 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 are linked to an increased rate of a disease. They can be:
A causal mechanism has been proven for some risk factors, but not in others.
Be able to explain the human and financial cost of these non-communicable diseases to an individual, a local community, a nation or globally. Many diseases are caused by the interaction of a number of factors. Be able to interpret data about risk factors for specified diseases. You should be able to understand the principles of sampling as applied to scientific data in terms of risk factors. You should be able to translate information between graphical and numerical forms; and extract and interpret information from charts, graphs and tables in terms of risk factors. You should be able to use a scatter diagram to identify a correlation between two variables in terms of risk factors. Keeping healthy - non-communicable diseases - risk factors for e.g. CVD, cancers Keeping healthy - diet and exercise, diabetes, body/mass/hip indexes
2.2.7 Cancer (revision study notes for AQA gcse combined science biology) You should be able to describe cancer as the result of changes in cells that lead to uncontrolled growth and division. Benign tumours and malignant tumours result from uncontrolled cell division. Benign tumours are growths of abnormal cells which are contained in one area, usually within a membrane. They do not invade other parts of the body. Malignant tumour cells are cancers. They invade neighbouring tissues and spread to different parts of the body in the blood where they form secondary tumours. Scientists have identified lifestyle risk factors for various types of cancer including smoking, obesity, common viruses and UV exposure. There are also genetic risk factors for some cancers. Keeping healthy - non-communicable diseases - risk factors for e.g. CVD, cancers
Topic 2.3 Plant tissues, organs and systems (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 2 "Organisation") 2.3.1 Plant tissues and organ (revision study notes for AQA gcse combined science biology) You should be able to explain how the structures of plant tissues are related to their functions. Plant tissues include:
The leaf is a plant organ. The structures of tissues in the leaf are related to their functions.
You should have done observation and drawing of a transverse section of leaf. Introduction to plant and animal cell structure and function - comparison of subcellular structures Photosynthesis, importance explained, limiting factors affecting rate, leaf adaptations Transport and gas exchange in plants, absorption of nutrients, leaf and root structure Microscopy - the development and use of microscopes in biology - optical and electron 2.3.2 Plant organ system (revision study notes for AQA gcse combined science biology) You should be able to explain how the structure of root hair cells, xylem and phloem are adapted to their functions. You should be able to explain the effect of changing temperature, humidity, air flow (air movement) and light intensity on the rate of transpiration. The roots, stem and leaves form a plant organ system for transport of substances around the plant. Root hair cells are adapted for the efficient uptake of water by osmosis and mineral ions by active transport. Xylem tissue transports water and mineral ions from the roots to the stems and leaves. It is composed of hollow tubes strengthened by lignin adapted for the transport of water in the transpiration stream. You should be able to describe the process of transpiration and translocation, including the structure and function of the stomata. Factors which affect the rate of transpiration are: temperature, humidity, air flow and light intensity. Know that the role of stomata and guard cells are to control gas exchange and water loss. Phloem tissue transports dissolved sugars from the leaves to the rest of the plant for immediate use or storage. The movement of food through phloem tissue is called translocation. Phloem is composed of tubes of elongated cells. Cell sap can move from one phloem cell to the next through pores in the end walls.
You should have done the experiments to:
Photosynthesis, importance explained, limiting factors affecting rate, leaf adaptations Microscopy - the development and use of microscopes in biology - optical and electron
Topic 3 Infection and response (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 3 "Infection and response") Know that pathogens are microorganisms such as viruses and bacteria that cause infectious diseases in animals and plants. They depend on their host to provide the conditions and nutrients that they need to grow and reproduce. They frequently produce toxins that damage tissues and make us feel ill. This section will explore how we can avoid diseases by reducing contact with them, as well as how the body uses barriers against pathogens. Once inside the body our immune system is triggered which is usually strong enough to destroy the pathogen and prevent disease. When at risk from unusual or dangerous diseases our body's natural system can be enhanced by the use of vaccination. Since the 1940s a range of antibiotics have been developed which have proved successful against a number of lethal diseases caused by bacteria. Unfortunately many groups of bacteria have now become resistant to these antibiotics. The race is now on to develop a new set of antibiotics. Topic 3.1 Communicable diseases (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 3 "Infection and response") Topic 3.1 Communicable diseases (revision study notes for AQA gcse combined science biology) 3.1.1 Communicable (infectious) diseases (revision study notes for AQA gcse combined science biology) You should be able to explain how diseases caused by viruses, bacteria, protists and fungi are spread in animals and plants. Be able to explain how the spread of diseases can be reduced or prevented. The spread of diseases can be reduced or prevented by eg simple hygiene measures, destroying vectors, isolation of infected individuals and vaccination. Pathogens are microorganisms that cause infectious disease. Pathogens may be viruses, bacteria, protists or fungi. They may infect plants or animals and can be spread by direct contact, by water or by air. Pathogens are microorganisms such as viruses and bacteria that cause infectious diseases in animals and plants. They depend on their host to provide the conditions and nutrients that they need to grow and reproduce. They frequently produce toxins that damage tissues and make us feel ill. This section explores how we can avoid diseases by reducing contact with them, as well as how the body uses barriers against pathogens. Once inside the body our immune system is triggered which is usually strong enough to destroy the pathogen and prevent disease. Bacteria and viruses may reproduce rapidly inside the body. Bacteria may produce poisons (toxins) that damage tissues and make us feel ill. Viruses live and reproduce inside cells, causing cell damage. Keeping healthy - communicable diseases - pathogen infections 3.1.2 Viral diseases (revision study notes for AQA gcse combined science biology) Know that measles is a viral disease showing symptoms of fever and a red skin rash. Measles is a serious illness that can be fatal if complications arise. For this reason most young children are vaccinated against measles. The measles virus is spread by inhalation of droplets from sneezes and coughs. HIV initially causes a flu-like illness. Unless successfully controlled with antiretroviral drugs the virus enters the lymph nodes and attacks the body’s immune cells. Late stage HIV, or AIDS, occurs when the body’s immune system becomes so badly damaged it can no longer deal with other infections or cancers. HIV is spread by sexual contact or exchange of body fluids such as blood which occurs when drug users share needles. Tobacco mosaic virus (TMV) is a widespread plant pathogen affecting many species of plants including tomatoes. It gives a distinctive ‘mosaic’ pattern of discolouration on the leaves which affects the growth of the plant due to lack of photosynthesis. Keeping healthy - communicable diseases - pathogen infections Plant diseases and defences against pathogens and pests
3.1.3 Bacterial diseases (revision study notes for AQA gcse combined science biology) Know that salmonella food poisoning is spread by bacteria ingested in food, or on food prepared in unhygienic conditions. In the UK, poultry are vaccinated against Salmonella to control the spread. Fever, abdominal cramps, vomiting and diarrhoea are caused by the bacteria and the toxins they secrete. Gonorrhoea is a sexually transmitted disease (STD) with symptoms of a thick yellow or green discharge from the vagina or penis and pain on urinating. It is caused by a bacterium and was easily treated with the antibiotic penicillin until many resistant strains appeared. Gonorrhoea is spread by sexual contact. The spread can be controlled by treatment with antibiotics or the use of a barrier method of contraception such as a condom. Keeping healthy - communicable diseases - pathogen infections 3.1.4 Fungal diseases (revision study notes for AQA gcse combined science biology) Rose black spot is a fungal disease where purple or black spots develop on leaves, which often turn yellow and drop early. It affects the growth of the plant as photosynthesis is reduced. It is spread in the environment by water or wind. Rose black spot can be treated by using fungicides and/or removing and destroying the affected leaves. Plant diseases and defences against pathogens and pests 3.1.5 Protist diseases (revision study notes for AQA gcse combined science biology) Know that the pathogens that cause malaria are protists. The malarial protist has a life cycle that includes the mosquito. Malaria causes recurrent episodes of fever and can be fatal. The spread of malaria is controlled by preventing the vectors, mosquitos, from breeding and by using mosquito nets to avoid being bitten. Keeping healthy - communicable diseases - pathogen infections 3.1.6 Human defence systems (revision study notes for AQA gcse combined science biology) You should be able to explain the nonspecific defence systems of the human body against pathogens. The human body defends itself against the entry of pathogens including:
You should be able to explain the role of the immune system in the defence against disease. If a pathogen enters the body the immune system tries to destroy the pathogen. White blood cells help to defend against pathogens by:
Keeping Healthy - How do our bodies defend themselves against infectious diseases? Keeping healthy - communicable diseases - pathogen infections including viruses and vaccination
3.1.7 Vaccination (revision study notes for AQA gcse combined science biology) You should be able to explain how vaccination will prevent illness in an individual, and how the spread of pathogens can be reduced by immunising a large proportion of the population. Know that vaccination involves introducing small quantities of dead or inactive forms of a pathogen into the body to stimulate the white blood cells to produce antibodies. If the same pathogen re-enters the body the white blood cells respond quickly to produce the correct antibodies, preventing infection.
If a large proportion of the population is immune to a pathogen, the spread of the pathogen is very much reduced. Be able to discuss the global use of vaccination in the prevention of disease. Keeping healthy - communicable diseases - pathogen infections including viruses and vaccination 3.1.8 Antibiotics and painkillers (revision study notes for AQA gcse combined science biology) You should be able to explain the use of antibiotics and other medicines in treating disease. Antibiotics, such as penicillin, are medicines that help to cure bacterial disease by killing infective bacteria inside the body. It is important that specific bacteria should be treated by specific antibiotics. The use of antibiotics has greatly reduced deaths from infectious bacterial diseases. However, the emergence of strains resistant to antibiotics is of great concern. Antibiotics cannot kill viral pathogens. Painkillers and other medicines are used to treat the symptoms of disease but do not kill pathogens. It is difficult to develop drugs that kill viruses without also damaging the body’s tissues. 3.1.9 Discovery and development of drugs (revision study notes for AQA gcse combined science biology) You should be able to describe the process of discovery and development of potential new medicines, including preclinical and clinical testing. Know that traditionally drugs were extracted from plants and microorganisms.
Most new drugs are synthesised by chemists in the pharmaceutical industry. However, the starting point may still be a chemical extracted from a plant. New medical drugs have to be tested and trialled before being used to check that they are safe and effective. New drugs are extensively tested for toxicity, efficacy and dose. Preclinical testing is done in a laboratory using cells, tissues and live animals.
Topic 4 Bioenergetics (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 4 "Bioenergetics") Know that sunlight is the ultimate source of energy for all living systems. Here you will explore how plants harness the Sun’s energy in photosynthesis in order to make food. This process liberates oxygen which has built up over millions of years in the Earth’s atmosphere. Both animals and plants use this oxygen to oxidise food in a process called aerobic respiration which transfers the energy that the organism needs to perform its functions. Conversely, anaerobic respiration does not require oxygen to transfer energy. During vigorous exercise the human body is unable to supply the cells with sufficient oxygen and it switches to anaerobic respiration. This process will supply energy but also causes the build-up of lactic acid in muscles which causes fatigue. Topic 4.1 Photosynthesis (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 4 "Bioenergetics") 4.1.1 Photosynthetic reaction Know that photosynthesis is represented by the word and symbol equations:
You should be able to describe photosynthesis
as an endothermic reaction in which energy is transferred from the Photosynthesis, importance explained, limiting factors affecting rate, leaf adaptations 4.1.2 Rate of photosynthesis (revision study notes for AQA gcse combined science biology) Know how the rate of photosynthesis may be affected by temperature, level of carbon dioxide, light intensity and amount of chlorophyll. Be able to explain the effects of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis and to interpret graphs of photosynthesis rate involving one limiting factor. You should be able to:
(HT only) Know that these factors interact and any one of them may be the factor that limits photosynthesis. (HT only) You should be able to explain graphs of photosynthesis rate involving two or three factors and decide which is the limiting factor. (HT only) You should understand and use inverse proportion – the inverse square law and light intensity in the context of photosynthesis. (HT only) Limiting factors are important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit. (HT only) Be able to use data to relate limiting factors to the cost effectiveness of adding heat, light or carbon dioxide to greenhouses. You should have done the practical to investigate the effect of a factor on the rate of photosynthesis. Photosynthesis, importance explained, limiting factors affecting rate, leaf adaptations 4.1.3 Uses of glucose from photosynthesis (revision study notes for AQA gcse combined science biology) The glucose produced in photosynthesis may be used:
Know that plants, to make proteins, also use nitrate ions that are absorbed from the soil. Know the chemical tests to identify starch, glucose and proteins using simple qualitative reagent tests. Photosynthesis, importance explained, limiting factors affecting rate, leaf adaptations
Topic 4.2 Respiration (revision study notes for AQA gcse combined science biology) (revision notes summary for AQA 9-1 GCSE Combined Science Trilogy: Biology Paper 1, Topic 4 "Bioenergetics") 4.2.1 Aerobic and anaerobic respiration (revision study notes for AQA gcse combined science biology) You should be able to describe cellular respiration as an exothermic reaction which is continuously occurring in living cells. The energy transferred supplies all the energy needed for living processes. Respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen), to transfer energy You should be able to compare the processes of aerobic and anaerobic respiration with regard to the need for oxygen, the differing products and the relative amounts of energy transferred. Respiration in cells can take place aerobically (using oxygen) or anaerobically (without oxygen), to transfer energy. Reactions which transfer energy to the environment are exothermic reactions. Organisms need energy for chemical reactions to build larger molecules, movement and keeping warm. Know that aerobic respiration is represented by the equations:
Anaerobic respiration in muscles is represented by the equation: glucose ===> lactic acid The energy transferred supplies all the energy needed for living processes. As the oxidation of glucose is incomplete in anaerobic respiration much less energy is transferred than in aerobic respiration. Anaerobic respiration in plant and yeast cells is represented by the equations:
Anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drink. RESPIRATION - aerobic and anaerobic in plants, fungi and animals, conditions, substrates etc.
4.2.2 Response to exercise (revision study notes for AQA gcse combined science biology) Know that during exercise the human body reacts to the increased demand for energy. The heart rate, breathing rate and breath volume increase during exercise to supply the muscles with more oxygenated blood. If insufficient oxygen is supplied anaerobic respiration takes place in muscles. The incomplete oxidation of glucose causes a build up of lactic acid and creates an oxygen debt. During long periods of vigorous activity muscles become fatigued and stop contracting efficiently. (HT only) Know that blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose. Oxygen debt is the amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells. You should have done the investigations into the effect of exercise on the body. RESPIRATION - aerobic and anaerobic in animals, conditions, substrates etc. Keeping healthy - diet and exercise 4.2.3 Metabolism (revision study notes for AQA gcse combined science biology)
You should be able to explain the importance of
sugars, amino acids, fatty acids and glycerol in the synthesis and
breakdown of Metabolism is the sum of all the reactions in a cell or the body. The energy transferred by respiration in cells is used by the organism for the continual enzyme controlled processes of metabolism that synthesise new molecules. Metabolism includes:
You need to know the details of all of the five aspects above, and they are all covered in more detail in the relevant specification section but are linked together here under the heading 'metabolism'. RESPIRATION - aerobic and anaerobic in animals, conditions, substrates etc. Enzymes - section on digestion and synthesis
ALL AQA GCSE (Grade 9-1) Level 1/Level 2 SCIENCES specifications and syllabus revision summary links AQA GCSE (Grade 9-1) BIOLOGY 8461 GCSE BIOLOGY 1st paper 1 (separate science Topics 1-4) AQA GCSE (Grade 9-1) BIOLOGY 8461 GCSE BIOLOGY 2nd paper 2 (separate science Topics 5-7) AQA GCSE (Grade 9-1) CHEMISTRY 8462 GCSE CHEMISTRY 1st Paper 1 (separate science Topics 1-5) AQA GCSE (Grade 9-1) CHEMISTRY 8462 GCSE CHEMISTRY 2nd Paper 2 (separate science Topics 6-10) AQA GCSE (Grade 9-1) PHYSICS 8463 GCSE PHYSICS 1st Paper 1 (separate science Topics 1-4) AQA GCSE (Grade 9-1) PHYSICS 8463 GCSE PHYSICS 2nd Paper 2 (separate science Topics 5-8) Watch out for HT Only sections AND make sure you know exactly which GCSE science course you are doing!
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