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Revision summary help OCR GCSE 21st Century Combined Science B biology exam papers - learning objectives B1-B3 exams biology F/H and 1st combined science F/H papers for 2020 exams onwards (re-edit) OCR Level 1/2 GCSE (Grade 9-1) in Combined Science B Biology (Twenty First Century Science) (J260) - OCR 21st Century GCSE Grade 9-1 Combined Science B revision summaries for biology Chapter B1 "You and your genes", Chapter B2 "Keeping healthy", Chapter B3 "Living together - food and ecosystems" for FT Biology paper 01, HT Biology Paper 05, FT Combined Science Paper 04, HT Combined Science Paper 08 LINK for OCR 21st Century Combined Science biology chapters B4-B6 LINK for OCR 21st Century 9-1 GCSE BIOLOGY B chapters B1-B3 LINK for OCR 21st Century 9-1 GCSE BIOLOGY B chapters B4-B7 This is a BIG website, you need to take time to explore it [SEARCH BOX] Use your mobile phone in 'landscape' orientation? See also OCR Gateway Sciences A Revision HELP Links 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 OCR GCSE 21st Century science B pages
In OCR 9-1 GCSE Twenty First Century Science B biology courses, note the following! Note: Combined Science Paper 04 assesses the contents of ALL the chapters of biology, chemistry and physics! Syllabus-specification CONTENT INDEX of revision summary notes (OCR GCSE 21st century combined science suite biology) What's assessed in this paper? (for OCR 9-1 GCSE Twenty First Century Combined Science B biology papers) SUMMARY Chapter B1: You and your genes (this page) Revision summary Chapter B1.1 What is the genome and what does it do? Revision summary Chapter B1.2 How is genetic information inherited? Revision summary Chapter B1.3 How can and should gene technology be used? SUMMARY Chapter B2: Keeping healthy (this page) Revision summary Chapter B2.1 What are the causes of disease? Revision summary Chapter B2.2 How do organisms protect themselves against pathogens? Revision summary Chapter B2.3 How can we prevent the spread of infections? Revision summary Chapter B2.4 How can lifestyle, genes and the environment affect my health? Revision summary Chapter B2.5 How can we treat disease? SUMMARY Chapter B3: Living together – food and ecosystems (this page) Revision summary Chapter B3.1 What happens during photosynthesis? Revision summary Chapter B3.2 How do producers get the substances they need? Revision summary Chapter B3.3 How are organisms in an ecosystem interdependent? Revision summary Chapter B3.4 How are populations affected by conditions in an ecosystem? SUMMARY Chapter B4: Using food and controlling growth (separate page) Chapter B4.1 What happens during cellular respiration? Chapter B4.2 How do we know about mitochondria and other cell structures? Chapter B4.3 How do organisms grow and develop? Chapter B4.4 Should we use stem cells to treat damage and disease? SUMMARY Chapter B5: The human body – staying alive (separate page) Chapter B5.1 How do substances get into, out of and around our bodies? Chapter B5.2 How does the nervous system help us respond to changes? Chapter B5.3 How do hormones control responses in the human body? Chapter B5.4 Why do we need to maintain a constant internal environment? Chapter B5.5 What role do hormones play in human reproduction? Chapter B5.6 What can happen when organs and control systems stop working? SUMMARY Chapter B6: Life on Earth – past, present and future (separate page) Chapter B6.1 How was the theory of evolution developed? Chapter B6.3 How is biodiversity threatened and how can we protect it? SUMMARY Chapter BCP7: Ideas about Science (separate page) IaS1 What needs to be considered when investigating a phenomenon scientifically? IaS2 What conclusions can we make from data? IaS3 How are scientific explanations developed? IaS4 How do science and technology impact society?
Biology Key Ideas for OCR 9-1 GCSE Twenty First Century Combined Science B GCSE 9-1 Biology papers Note: Combined Science Paper 04 assesses the contents of ALL the chapters of biology, chemistry and physics! Biology is the science of living organisms (including animals, plants, fungi and microorganisms) and their interactions with each other and the environment. The study of biology involves collecting and interpreting information about the natural world to identify patterns and relate possible cause and effect. Biological information is used to help humans improve their own lives and strive to create a sustainable world for future generations. You should understand how, through the ideas of biology, the complex and diverse phenomena of the natural world can be described in terms of a small number of key ideas which are of universal application, and which can be illustrated in the separate topics set out below. These ideas include:
Chapter B1: You and your genes (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B1 "You and your genes") The inheritance of genetic information from
each generation to the next is a fundamental idea in science; it can help us
answer questions about why we look the way we do, and build a foundation for
later exploration of ideas about genetic diseases, cell division and growth, and
evolution.
From your Key Stages 1 to 3 science studies about genes and inheritance you should ...
Chapter Topic B1.1 What is the genome and what does it do? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B1 "You and your genes") All organisms contain genetic material. Genetic material contains instructions that control how cells and organisms develop and function. Most of an organism’s characteristics depend on these instructions and are modified by interaction with the environment. Genetic material in plant and animal cells is located in the nucleus, one of the main sub-cellular structures. In organisms whose cells do not have a nucleus (e.g. bacteria) the genetic material is located in the cytoplasm. All the genetic material of a cell is the organism’s genome. In most organisms the genome is packaged into chromosomes. Chromosomes are long molecules of DNA. Genes are sections of this DNA. In the cells of plants and animals, chromosomes occur in pairs. The two chromosomes in a pair each carry the same genes. The two versions of each gene in the pair are called alleles, and can be the same or different. A different version of a gene is a genetic variant. The genotype of an organism is the combination of alleles it has for each gene; the phenotype is the characteristic that results from this combination and interaction with the environment. Genes tell a cell how to make proteins by joining together amino acids in a particular order. 1. (a) Be able to explain how the nucleus and genetic material of eukaryotic cells (plants and animals) and the genetic material, including plasmids, of prokaryotic cells are related to cell functions Introduction to plant and animal cell structure and function 1. (b) Be able to describe how to use a light microscope to observe a variety of plant and animal cells - Practical work: use a microscope to look at a variety of plant and animal cells, extract DNA from plant tissue. Microscopy - the development and use of microscopes in biology 2. Be able to describe the genome as the entire genetic material of an organism. 3. Be able to describe DNA as a polymer made up of nucleotides, forming two strands in a double helix. DNA structure gcse biology revision notes 4. Be able to describe simply how the genome and its interaction with the environment influence the development of the phenotype of an organism, including the idea that most characteristics depend on instructions in the genome and are modified by interaction of the organism with its environment. You are not expected to describe epigenetic effects. 5. Be able to explain the terms chromosome, gene, allele, variant, genotype and phenotype. An introduction to genetic variation and the formation and consequence of mutations 6. Be able to explain the importance of amino acids in the synthesis of proteins, including the genome as instructions for the polymerisation of amino acids to make proteins.
Chapter Topic B1.2 How is genetic information inherited? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B1 "You and your genes") During sexual reproduction, each offspring inherits two alleles of each gene; one allele from each gamete. The two alleles can be two copies of the same genetic variant (homozygous) or different variants (heterozygous). A variant can be dominant or recessive, and the combination of alleles determines what effect the gene has. Genetic diagrams such as family trees and Punnett squares can be used to model and predict outcomes of the inheritance of characteristics that are determined by a single gene. However, most characteristics depend on the instructions in multiple genes and other parts of the genome. Principles of inheritance of (single gene) characteristics were demonstrated in ideas developed by Gregor Mendel, using pea plants. Mendel’s work illustrates how scientists develop explanations that account for data they have collected. (HT only) Our understanding of genetics has developed greatly since Mendel did his work; we now know that most characteristics depend upon interactions between genetic variants in multiple parts of the genome. Today, scientists sequence whole genomes to investigate how genetic variants influence an organism’s characteristics. 1. Be able to explain the terms gamete, homozygous, heterozygous, dominant and recessive.
2. Be able to explain single gene inheritance, including dominant and recessive alleles and use of genetic diagrams 3. Be able to predict the results of single gene crosses. 4. Be able to use direct proportions and simple ratios in genetic crosses. 5. Be able to use the concept of probability in predicting the outcome of genetic crosses. 6. Be able to recall that most phenotypic features are the result of multiple genes rather than single gene inheritance.
Know that a human individual’s sex is determined by the inheritance of genes located on sex chromosomes; specifically, genes on the Y chromosome trigger the development of testes. Inherited characteristics and human sexual reproduction, genetic fingerprinting and its uses 8. Be able to describe sex determination in humans. An introduction to genetic variation and the formation and consequence of mutations Introduction to the inheritance of characteristics and genetic diagrams (including Punnett squares)
Chapter Topic B1.3 How can and should gene technology be used? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B1 "You and your genes") Comparing the genomes of individuals with and without a disease can help to identify alleles associated with the disease. Once we have identified such alleles we can test for them in adults, children, fetuses and embryos, to investigate their risk of developing certain diseases and of passing the alleles to their offspring (including the identification of ‘carriers’ of recessive alleles). Genetic testing can also help doctors to prescribe the correct drugs to a patient (‘personalised medicine’), by testing for alleles that affect how drugs will work in their body. Another application of gene technology is genetic engineering, in which the genome is modified to change an organism’s characteristics. Genes from one organism can be added to another because all organisms use the same genetic code. Genetic engineering has been used to introduce characteristics useful to humans into organisms such as bacteria and plants. Gene technology could help us provide for the needs of society, by improving healthcare and producing enough food for the growing population. But with genetic testing we must also consider how the results will be used and by whom, and the risks of false positives/negatives and miscarriage (when sampling amniotic fluid). With genetic engineering there are concerns about the spread of inserted genes to other organisms, the need for long-term studies to check for adverse reactions, and moral concerns about modifying genomes and the application of the technology to modify humans. 1. Be able to discuss the potential importance for medicine of our increasing understanding of the human genome, including the discovery of alleles associated with diseases and the genetic testing of individuals to inform family planning and healthcare.
2. Be able to describe genetic engineering as a process which involves modifying the genome of an organism to introduce desirable characteristics. Genetic engineering: uses - making insulin, medical applications, GM crops, food security 3. (HT only) Be able to describe the main steps in the process of genetic engineering including:
4. Be able to explain some of the possible benefits and risks, including practical and ethical considerations, of using gene technology in modern agriculture and medicine Genetic engineering: uses - making insulin, medical applications, GM crops, food security
Chapter B2: Keeping Healthy (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B2 "Keeping healthy") Issues of risk, ethics and social responsibility related to disease prevention and treatment in humans and plants are often in the news. Understanding the science of health and disease enables us to consider the issues critically, and to explore possible answers.
From your Key Stages 1 to 3 science studies about on health and disease you should ..
Chapter Topic B2.1 What are the causes of disease? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B2 "Keeping healthy") The health of most organisms will be compromised by disease during their lifetime. Physical and mental health can be compromised by disease caused by infection by a pathogen, an organism’s genes, environment or lifestyle, or trauma. Disease damages host cells and impairs functions, causing symptoms. However, an unhealthy organism may not always show symptoms of disease, particularly during the ‘incubation period’ after infection with a pathogen. Some diseases are communicable: they are caused by infection with pathogenic bacteria, viruses, protists and fungi, and can be spread from organism to organism in bodily fluids, on surfaces, and in food and water. Other diseases are non-communicable: they are not caused by infection but are associated with genetic, environmental and lifestyle factors. Some common diseases illustrate different types of pathogen and common routes of spread and infection, including:
Keeping healthy - communicable diseases - pathogen infections Keeping healthy - non-communicable diseases - risk factors for e.g. cancers Plant diseases and defences against pathogens and pests 1. Be able to describe the relationship between health and disease
2. Be able to describe different types of diseases (including communicable and non-communicable diseases) 3. Be able to explain how communicable diseases (caused by viruses, bacteria, protists and fungi) are spread in animals and plants 4. Be able to describe common human infections including influenza (viral), Salmonella (bacterial), Athlete’s foot (fungal) and malaria (protist) and sexually transmitted infections in humans including HIV/AIDS (viral) Keeping healthy - communicable diseases - pathogen infections 5. Be able to describe plant diseases including tobacco mosaic virus (viral), ash dieback (fungal) and crown gall disease (bacterial) Plant diseases and defences against pathogens and pests
Chapter Topic B2.2 How do organisms protect themselves against pathogens? (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B2 "Keeping healthy") Humans have physical, chemical and bacterial defences that make it difficult for pathogens to enter the blood. These include the skin and mucus, stomach acid, saliva, tears, and bacteria in the gut. Platelets help to seal wounds to reduce the chance of pathogens entering the blood. These defences are always present, and are not produced in response to a specific pathogen. Plants have physical defences against pathogens, including the leaf cuticle and cell wall. The immune system of the human body works to protect us against disease caused by pathogens. White blood cells destroy pathogens that enter the blood system. White blood cells have receptors that recognise antigens on pathogens, to distinguish between non-self and self. Different types of white blood cell are adapted to either ingest and digest pathogens, or produce antibodies to disable them or tag them for attack by other white blood cells. An antibody is specific for (only recognises) a particular antigen. Once the body has made antibodies against a pathogen, memory cells stay in the body to make antibodies quickly upon re-infection (immunity). 1. Be able to describe non-specific defence systems of the human body against pathogens, including examples of physical, chemical and microbial defences 2. Be able to explain how platelets are adapted to their function in the blood. 3. Be able to explain the role of the immune system of the human body in defence against disease 4. Be able to explain how white blood cells are adapted to their functions in the blood, including what they do and how it helps protect against disease. Keeping Healthy - How do our bodies defend themselves against infectious diseases?
Chapter Topic B2.3 How can we prevent the spread of infections? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B2 "Keeping healthy") Reducing and preventing the spread of communicable diseases in animals and plants helps prevent loss of life, destruction of habitats and loss of food sources. For plants, strategies include regulating the movement of plant material, sourcing healthy plants and seeds, destroying infected plants, polyculture, crop rotation and chemical and biological control. For animals, including humans, strategies include vaccination (to establish immunity), contraception, hygiene, sanitation, sterilising wounds, restricting travel, and destruction of infected animals. The likely effectiveness, benefits, risks and cost of each strategy must be considered, and an individual’s right to decide balanced with what is best for society. 1. Be able to explain how the spread of communicable diseases may be reduced or prevented in animals and plants, to include a minimum of one common human infection, one plant disease and sexually transmitted infections in humans including HIV/AIDS.
2. Be able to explain the use of vaccines in the prevention of disease, including the use of safe forms of pathogens and the need to vaccinate a large proportion of the population Keeping healthy - communicable diseases - pathogen infections
Chapter Topic B2.4 How can lifestyle, genes and the environment affect health? (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B2 "Keeping healthy") Whether or not a person develops a non-communicable disease depends on many factors, including the genetic variants they inherited, their environment and aspects of their lifestyle. The interaction of genetic and lifestyle factors can increase or decrease the risk. 1. (a) Be able to describe how the interaction of genetic and lifestyle factors can increase or decrease the risk of developing non-communicable human diseases, including cardiovascular diseases, many forms of cancer, some lung and liver diseases and diseases influenced by nutrition, including type 2 diabetes. Keeping Healthy - Diet and Exercise Homeostasis - control of blood sugar level - insulin and diabetes 1. (b) Be able to describe how to practically investigate the effect of exercise on pulse rate and recovery rate
Keeping Healthy - Diet and Exercise 2. Be able to use given data to explain the incidence of non-communicable diseases at local, national and global levels with reference to lifestyle factors, including exercise, diet, alcohol and smoking Keeping Healthy - Diet and Exercise Homeostasis - control of blood sugar level - insulin and diabetes 3. In the context of data related to the causes, spread, effects and treatment of disease be able to:
4. Be able to describe interactions between different types of disease. Keeping healthy - communicable diseases - pathogen infections
Chapter Topic B2.5 How can we treat disease? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B2 "Keeping healthy") Humans have developed medicines that can control or eliminate the cause of some diseases and/or reduce the length or severity of symptoms. Antibiotics are becoming less effective due to the appearance of antibiotic resistant bacteria. For non-communicable diseases such as cardiovascular diseases, strategies that lower the risk of developing the disease have benefits compared to treatments administered later. Many factors need to be considered when prescribing treatments, including the likely effectiveness, risk of adverse reactions and the costs and benefits to the patient and others. 1. Be able to explain the use of medicines, including antibiotics, in the treatment of disease - risk and decision making in the context of medicines and treatment. 2. Be able to calculate cross-sectional areas of bacterial cultures and of clear zones around antibiotic discs on agar jelly using πr2. See also Culturing microorganisms like bacteria - testing antibiotics/antiseptics 3. Be able to evaluate some different treatments for lowering the risk of cardiovascular disease and treating it, including lifestyle changes, medicines and surgery. Keeping healthy - diet and exercise, diabetes, body/mass/hip indexes Studying the genomes and proteins of pathogens and host cells can suggest targets for new medicines. Large libraries of substances are screened for their ability to affect a target. It is unlikely that a perfect medicine will be found during screening, but substances are selected for modification and further tests. All new medicines have to be tested before they are made widely available. Preclinical testing, for safety and effectiveness, uses cultured human cells and animals. Clinical testing uses healthy human volunteers to test for safety, and humans with the disease to test for safety and effectiveness. ‘Open-label’, ‘blind’ and ‘double-blind’ trials can be used. There are ethical questions around using placebos in tests on people with a disease 4. Be able to describe the process of discovery and development of potential new medicines including preclinical and clinical testing - appreciate ethical issues in the context of using placebos in clinical testing of new medicines.
Chapter B3: Living together - food and ecosystems (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B3 "Living together food & ecosystems") Introduction to Chapter B3 (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B3 "Living together food & ecosystems") All living organisms depend on the ability of photosynthetic organisms to synthesise glucose from carbon dioxide and water in the presence of light, and on feeding relationships to transfer biomass through communities. From your Key Stage 3 Science, learners will be familiar with the reactants and products of photosynthesis, and the need for light in the process. In Topics B3.1 and B3.2 you study in the context of photosynthesis, fundamental concepts in biology, including enzyme action and the movement of substances by diffusion, osmosis and active transport. You will expand your knowledge of the interdependencies between organisms within ecosystems in Topic B3.3, through understanding of food webs, competition for resources, and the cycling of substances. In Topic B3.4 you study the effects that environmental changes and human activities can have on interacting populations within ecosystems. From your Key Stages 1 to 3 science studies about food and ecosystems you should ...
Chapter Topic B3.1 What happens during photosynthesis? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B3 "Living together food & ecosystems") Producers make glucose using photosynthesis. Some of the glucose is used as the fuel for cellular respiration, some is converted into starch and then stored, and the rest is combined with elements absorbed from the environment to make carbohydrates, lipids and proteins (biomass) for growth. Photosynthesis involves many chemical reactions, but can be summarised in two main stages. The first stage requires light and chlorophyll (located in chloroplasts in plant cells) to split water molecules into hydrogen and oxygen. The hydrogen is transferred to the second stage, but the oxygen is released into the atmosphere as a waste product. The second stage combines carbon dioxide with hydrogen to make glucose. The reactions in photosynthesis and many other biological processes are catalysed by enzymes. The lock and key model can be used to explain enzyme action. It can also be used to make predictions about the effect on the rate of enzyme-catalysed reactions when the substrate concentration, temperature and pH are changed. 1. (a) Be able to describe the process of photosynthesis, including the inputs and outputs of the two mains stages and the requirement of light in the first stage, and describe photosynthesis as an endothermic process 1b. (b) Be able to describe practical investigations into the requirements and products of photosynthesis.
Photosynthesis, importance explained, limiting factors affecting rate, leaf adaptations 2. Be able to explain how chloroplasts in plant cells are related to photosynthesis. 3. (a) Be able to explain the mechanism of enzyme action including the active site, enzyme specificity and factors affecting the rate of enzyme- catalysed reactions, including substrate concentration, temperature and pH. 3b. (b) Be able to describe practical investigations into the effect of substrate concentration, temperature and pH on the rate of enzyme controlled reactions.
ENZYMES - structure, function, optimum conditions, investigation experiments See also Enzymes and Biotechnology (gcse chemistry notes) Appreciate that understanding of how factors affect enzyme activity helps to explain the effects of temperature and carbon dioxide concentration on the rate of photosynthesis. The effect of light intensity is explained by the need for light to bring about reactions in photosynthesis. (HT only) Light intensity is inversely proportional to the square of the distance from the light source (the inverse square law); this helps us explain why the rate of photosynthesis changes in the way that it does with distance from a point light source. 4. (a) Be able to explain the effect of temperature, light intensity and carbon dioxide concentration on the rate of photosynthesis. 4. (b) Be able to describe practical investigations into the effect of environmental factors on the rate of photosynthesis.
5. (HT only) Be able to use the inverse square law to explain changes in the rate of photosynthesis with distance from a light source. 6. (HT only) Be able to explain the interaction of temperature, light intensity and carbon dioxide concentration in limiting the rate of photosynthesis, and use graphs depicting the effects. 7. In the context of the rate of photosynthesis be able to:
Photosynthesis, importance explained, limiting factors affecting rate, leaf adaptations
Chapter Topic B3.2 How do producers get the substances they need? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B3 "Living together food & ecosystems") The ways in which photosynthetic organisms take in carbon dioxide and water for photosynthesis, and release the waste product oxygen, illustrate the principles of diffusion and osmosis. Generally, molecules move from a region of their higher concentration to a region of their lower concentration; the difference in concentration drives a change towards equal concentration. Carbon dioxide and oxygen molecules move by diffusion, through cell membranes in single-cellular (prokaryotic) producers, and through stomata and cell membranes in plants. Water molecules move by osmosis through cell membranes; projections from root cells (‘root hairs’) of plants increase the surface area for osmosis. The way in which photosynthetic organisms take in nitrogen (to make proteins) illustrates the process of active transport. Producers get nitrogen from nitrate ions (NO3–). Molecules of water and gases can diffuse through partially-permeable cell membranes but nitrate ions cannot; producers use energy from molecules of ATP to transport nitrate ions through the cell membrane by active transport. Plants do not have blood to transport substances around the organism; they have transport vessels formed from xylem and phloem. Water and ions (e.g. nitrate) in aqueous solution are moved through xylem from the roots and up the stem/trunk by transpiration, to replace water that evaporates from open stomata. 1. Be able to describe some of the substances transported into and out of photosynthetic organisms in terms of the requirements of those organisms, including oxygen, carbon dioxide, water and mineral ions.
2. (a) Be able to explain how substances are transported into and out of cells through diffusion, osmosis and active transport. 2. (b) Be able to describe practical investigations into the processes of diffusion and osmosis. You are not expected to explain osmosis in terms of water potential Diffusion, osmosis and active transport 3. Be able to explain how the partially-permeable cell membranes of plant cells and prokaryotic cells are related to diffusion, osmosis and active transport 4. Be able to explain how water and mineral ions are taken up by plants, relating the structure of the root hair cells to their function 5. (a) Be able to explain how the structure of the xylem and phloem are adapted to their functions in the plant. 5. (b) Be able to describe how to use a light microscope to observe the structure of the xylem and phloem. Microscopy - the development and use of microscopes in biology
Sugars are moved through phloem from photosynthetic to non-photosynthetic tissues by translocation. Sugars are loaded into phloem by active transport, then water moves into the concentrated solution by osmosis and pushes the substances along the tube. The rate of water uptake by a plant can be affected by environmental factors. Light intensity and temperature affect the rate of photosynthesis (and therefore the demand for water), while air movement and temperature affect the rate of water loss from aerial parts of the plant. 6. (a) Be able to describe the processes of transpiration and translocation, including the structure and function of the stomata. 6. (b) Be able to describe how to use a light microscope to observe the structure of stomata. 6. (c) Be able to describe how to use a simple potometer.
7. (a) Be able to explain the effect of a variety of environmental factors on the rate of water uptake by a plant, to include light intensity, air movement, and temperature 7. (b) Be able to describe practical investigations into the effect of environmental factors on the rate of water uptake by a plant. 8. In the context of water uptake by plants be able to:
Chapter B3.3 How are organisms in an ecosystem interdependent? (OCR GCSE 21st century combined science suite biology) (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B3 "Living together food & ecosystems") Producers take in carbon and nitrogen compounds from their environment and use them (along with oxygen, hydrogen and other elements) to make small organic molecules including sugars, fatty acids, glycerol and amino acids. These small molecules are used to make larger organic molecules, such as long-chain carbohydrates, lipids and proteins. The larger molecules are used to build new structures (e.g. membranes, organelles). Consumers can only get their supply of carbon and nitrogen compounds by eating producers (or other consumers that ate producers) and digesting the biomass. This releases the small molecules so they can be absorbed and then used to build biomass in the consumer. The transfer of biomass between organisms is one way in which the populations in a community are interdependent, and can be modelled using a food web (IaS3). The amount of biomass present at each trophic level is not shown by a food web, but can be modelled using a pyramid of biomass. The size of each population in a community is limited by predation and competition for food and other resources including space, water, light, shelter, mates, pollinators and seed dispersers. Substances essential to life, including water and carbon, cycle through the biotic and abiotic components of ecosystems so that they can be used and reused by organisms. Water cycles through precipitation, food chains, transpiration, excretion, run-off, flow through streams/rivers/oceans, and evaporation. Carbon cycles through photosynthesis, food chains, cellular respiration, decomposition and combustion. Decomposition is catalysed by enzymes released by microorganisms. Carbon cycle, nitrogen cycle, water cycle, decomposition - decay investigation, biogas Ecosystems - biotic & abiotic factors - interactions between organisms - interdependency Food chains, food webs, trophic levels and biomass Enzymes - structure, functions, optimum conditions, investigation experiments, digestion 1. (a) Be able to explain the importance of sugars, fatty acids and glycerol, and amino acids in the synthesis and breakdown of carbohydrates, lipids and proteins. 1. (b) Be able to describe the use of qualitative tests for biological molecules.
2. Be able to describe photosynthetic organisms as the main producers of food and therefore biomass for life on Earth. 3. Be able to describe some of the substances transported into organisms in terms of the requirements of those organisms, including dissolved food molecules. 4. Be able to describe different levels of organisation in an ecosystem from individual organisms to the whole ecosystem. 5. Be able to explain the importance of interdependence and competition in a community. 6. Be able to recall that many different substances cycle through the abiotic and biotic components of an ecosystem, including carbon and water.
7. Be able to explain the importance of the carbon cycle and the water cycle to living organisms. 8. Be able to explain the role of microorganisms in the cycling of substances through an ecosystem. 9. Be able to calculate the percentage of mass, in the context of the use and cycling of substances in ecosystems. Carbon cycle, nitrogen cycle, water cycle, decomposition - decay investigation, biogas Ecosystems - biotic & abiotic factors - interactions between organisms - interdependency Food chains, food webs, trophic levels and biomass Enzymes - structure, functions, optimum conditions, investigation experiments, digestion
Chapter B3.4 How are populations affected by conditions in an ecosystem? (Revision for OCR GCSE 9–1 Twenty First Century Science Combined Science B biology paper 01, Topics for Chapter B3 "Living together food & ecosystems") The distribution and abundance of organisms in an ecosystem depends on abiotic and biotic factors. The size of one or more populations in a community may be affected if the environmental conditions change, or if a new chemical, competitor, predator or pathogen is introduced. A chemical can bioaccumulate in a food chain to toxic concentration, and some can cause eutrophication. A change in the size of a population will affect other populations in the same community. The distribution and abundance of organisms, and changing conditions, within an ecosystem can be investigated using techniques including: identification keys; transects and quadrats; capture, mark, release and recapture; sampling living indicators; and using instruments to measure abiotic factors such as temperature, light intensity, soil moisture and pH. Ecosystems - biotic & abiotic factors - interactions between organisms - interdependency Food chains, food webs, trophic levels and biomass Biodiversity and ecological surveying - using quadrats and transects 1. Be able to explain how some abiotic and biotic factors affect communities, including environmental conditions, toxic chemicals, availability of food and other resources, and the presence of predators and pathogens.
2. Be able to describe how to carry out a field investigation into the distribution and abundance of organisms in an ecosystem and explain how to determine their numbers in a given area 3. In the context of data related to organisms within a population:
Ecosystems - biotic & abiotic factors - interactions between organisms - interdependency Food chains, food webs, trophic levels and biomass Biodiversity and ecological surveying - using quadrats and transects
ALL OCR GCSE (Grade 9-1) Level 1/Level 2 TWENTY FIRST CENTURY SCIENCE B specifications and syllabus revision summary links Be aware that both Paper 1 and Paper 2 for biology, chemistry or physics assess content from ALL 6 chapters 1-6 !!! Paper 1 is called "Breadth in biology/chemistry/physics" and Paper 2 is called "Depth in biology/chemistry/physics" Watch out for HT Only sections AND make sure you know exactly which GCSE science course you are doing! See also OCR Gateway Sciences A Revision Links
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