Biodiversity can be thought of as the variation that exists within and between all forms of life. 1 The Microscope in Cell Studies for the CIE A Level Biology syllabus, written by the Biology experts at Save My Exams. When an impulse travelling along the axon of a motor neurone arrives at the presynaptic membrane, the action potential A bundle of neurones is known as a nerve. Four infectious diseases of worldwide importance are: cholera, malaria, tuberculosis (TB) and HIV/ AIDS. Information is sent through the nervous 10. Enzymes are globular proteins with complex tertiary structures. Revision notes on 9. For example, onion root tip cells divide once every 20 hours (roughly) but human intestine epithelial cells divide once every 10 . There is also a network of blood vessels associated with each nephron: Within the Bowman’s capsule of each nephron is a Jun 3, 2011 · There are two types of somatic gene therapy: Ex vivo – the new gene is inserted via a virus vector into the cell outside the body. Structure of the Mitochondrion. For example: The lungs excrete the waste product carbon dioxide by gas exchange and the act of breathing out (exhalation) The kidneys produce urine that contains the waste product Managing Ecosystems Sustainably. They are located between a neurone and a muscle cell. Mass transport is the bulk movement of gases or liquids in one direction, usually via a system of vessels and tubes. 20,000 + revision notes • Past papers and mark schemes • 100,000 + practice questions and model answers • And lots more. Water potential describes the tendency of water to move out of a solution. It can be defined as: The net movement, as a result of the random motion of its molecules or ions, of a substance from a region of its higher concentration to a region of its lower concentration. The nephron is the functional unit of the kidney – the nephrons are responsible for the formation of urine. Blinking. 1 Eukaryotic Cell Structures & Functions for the CIE A Level Biology syllabus, written by the Biology experts at Save My Exams. A bundle of neurones is known as a nerve. The hypothalamus. The following features are found in all types of neurone. 5 Conservation. Acetyl CoA formed from fatty acids (after the breakdown of lipids) and amino acids enters directly into the Krebs Cycle from other We're on a mission to take the guesswork out of Biology revision. Splitting the glucose molecule in two. Relationships of Organisms with one another & with the Environment. Primary Immune Response (Advanced) Lymphocytes are another type of white blood cell. Designed for the Edexcel A Level Biology syllabus. Photosynthesis occurs in autotrophic organisms such as plants, algae and cyanobacteria. The Definition of a Population. All organisms require a constant supply of energy to maintain their cells and stay alive. The control of blood glucose concentration. Three key homeostatic mechanisms are: Thermoregulation – the control of body temperature. Family: Canidae. Meet all our experts. This is due to the processes of independent assortment and crossing over. e. 7 Specialised Cells for the OCR A Level Biology syllabus, written by the Biology experts at Save My Exams. Osmoregulation is a key part of homeostasis. Optical microscopes cannot be used to observe smaller organelles such as ribosomes, the endoplasmic reticulum or lysosomes. 2 Antibodies & Vaccination. A gene mutation is a change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide. These regions include: The cerebrum. 1 Structure of Bacteria & Viruses for the Edexcel A (SNAB) A Level Biology syllabus, written by the Biology experts at Save My Exams. Each stage occurs at a particular location in a eukaryotic cell: Glycolysis takes place in the cell cytoplasm. Amylose – one of the two polysaccharides that is used to form starch (the storage polysaccharide in plants) Amylopectin (70 - 90% of starch) 1,4 glycosidic bonds between α-glucose molecules but also 1,6 glycosidic bonds form between glucose molecules One of the genes for coat colour in horses is Agouti. Revision notes on 13. Allele a → chestnut coat. Some are formed from a single polypeptide, whilst others are made Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning. Progress tracking across 45+ topics & 2695+ questions, sorted by difficulty. The location and structure of a nephron. Energy is stored within these organic compounds. The Nervous System. grades 2x. It belongs to the following taxonomic groups: Domain: Eukarya. 2 kg per square metre). The lock-and-key hypothesis. Past paper and exam-style questions, organised by topic. 6. Just select your qualification level and exam board below, and dive into everything you’ll need to make Chromosomes are located in the nucleus of cells. Extremes of heat or pH can change the shape of the active site, preventing substrate binding – this is called denaturation. Starch (for storage) Sucrose (for translocation around the plant) Cellulose (for making cell walls) Photosynthesis occurs in two, closely-linked stages: the light-dependent stage, which takes place in the thylakoids, and the light-independent stage, which takes place in the stroma. 1 Common Pathogens & Communicable Diseases for the OCR A Level Biology syllabus, written by the Biology experts at Save My Exams. 8 Anaerobic Respiration for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams. water H 2 O, which is where ‘hydrate’ comes from) they can be represented by the formula Cx (H2O)y. Homeostatic mechanisms help organisms to keep their internal body conditions near constant. 4 Required Practical: Measuring Enzyme Activity for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams. Respiration can take place with oxygen ( aerobically) or without oxygen ( anaerobically ). Some of these differences are caused by differences in genes, which is genetic variation. Make your way through our clear revision notes, Biology past papers, typical exam questions, fully-explained model answers and more tailored to your Biology specification. There is also a network of blood vessels associated with each nephron: Within the Bowman’s capsule of each nephron is a Revision notes on 2. Sequencing Methods. 1 The Human Gas Exchange System for the CIE A Level Biology syllabus, written by the Biology experts at Save My Exams. 1 The Immune System. A synapse. It can be assessed on different scales. The chain termination method is also known as Sanger sequencing. Alistair has continued to pursue his interests in ecology and environmental science, recently gaining an MSc in Wildlife Biology & Conservation with Edinburgh Napier University. Kingdom: Plantae. The primary structure of a protein. Species: lupus. They are smaller than phagocytes. Mode of Enzyme Action. 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The molecules or ions move down a concentration gradient. They are produced in the bone marrow before birth. Produce useful products, such as foods and medicines. Get started. A Punnett square diagram shows the possible combinations of alleles that could be produced in the offspring. There is also a network of blood vessels associated with each nephron: Within the Bowman’s capsule of each nephron is a Oxidative phosphorylation is the last stage of aerobic respiration. Specialised sensory neurones, known as osmoreceptors, monitor the water potential of the blood (these osmoreceptors are found in an area of the brain known as the hypothalamus) If the osmoreceptors detect a This allows the liver to absorb and metabolise many of the nutrients that are absorbed into the blood in the small intestine. The Structure of ATP. The number and range of different ecosystems and habitats on the entire planet. Each allele can produce a different coat colour: Allele A → black coat. They have a large nucleus that fills most of the cell. Phenotypic variation is the difference in features between individuals of the same species. Cell signalling. 6 Control of Blood Glucose Concentration for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams. The human nervous system consists of the: Central nervous system (CNS) – the brain and the spinal cord. This creates a high SA:V ratio for the diffusion of gases. A gene is a short length of DNA found on a chromosome that codes for a specific protein. This could be a structural protein such as collagen found in skin cells, an enzyme or a hormone. Revision notes on 1. Humans, in the way that they set up and manage an ecosystem, are in control of whether that ecosystem is sustainable or not. Revision notes, past papers and practice questions for Edexcel A Level Biology, written by our expert team of teachers and examiners. This gene for coat colour is found on the same position on the same chromosome for all horses. mRNA - the base sequences on messenger RNA molecules are used by ribosomes to form polypeptide chains. Osmosis is the net movement of water molecules from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution), through a partially permeable membrane. It results in the production of many molecules of ATP and the production of water from oxygen. The allele a gamete received for one gene does Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning. 1 The Human Gas Exchange System for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams. 3 The Cell Surface Membrane for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams. biomass) of 0. Microorganisms are the most useful group of organisms that carry out biotechnological processes because they. Respiration is enzyme-controlled. Controlling how much light enters the eye. nuclear division (mitosis) cell division (cytokinesis) The length of the cell cycle is very variable depending on environmental conditions, the cell type and the organism. Carry out useful services, such as sewage treatment, composting and bioremediation. Osmoregulation – the control of the water potential of body fluids. 2. Revision notes on 18. 4. Variation is defined as differences between individuals of the same species. The fluid mosaic model also helps to explain: Passive and active movement between cells and their surroundings. The three types of carbohydrates are Leverage the knowledge and expertise of40+ examiners and educators. As H and O atoms are always present in the ratio of 2:1 (eg. Digestion is a process in which relatively large, insoluble biological molecules in food (such as starch, proteins) are hydrolysed into smaller, soluble molecules that can be absorbed across the cell membranes into the bloodstream and delivered to cells in the body. Immunity. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning. The lungs are connected to the circulatory system. In the process of photosynthesis, light energy is trapped and used to convert simple inorganic compounds into complex organic compounds. Blood or bone marrow cells are extracted and exposed to the virus which inserts the gene into these cells. Nucleotides are made up of three components: A nitrogen-containing base (also known as a nitrogenous base) A pentose sugar (containing 5 carbon atoms) A phosphate group. Carbohydrates are one of the main carbon-based compounds in living organisms. 2 Nutrient Cycles. The basic structure of a nucleotide. Here, you'll find an array of revision notes, topic questions, fully explained model answers, past exam papers and more, meticulously organized to simplify your search. Neurones coordinate the activities of sensory receptors (eg. Glycolysis is the first stage of respiration. In the 1890’s the first model of enzyme activity was described by Emil Fischer: The Process of Digestion. Vaccinations produce long-term immunity as they cause memory cells to be created. If the grass field is 200 m² in size, then the Past paper and exam-style questions, organised by topic. The axon of some neurones is insulated by a fatty sheath with small uninsulated Topic Questions. tRNA - amino acids are carried to the Enzymes are biological catalysts. The helix shape enables it to be more compact and thus it is more resistant to digestion. If the dry mass of the grass from 1 m² of a field is found to be 0. Membranes are vital structures found in all cells. The control of the water potential of body fluids is known as osmoregulation. When it is secreted it increases the concentration of blood glucose. Functional RNA molecules are required for protein synthesis. The Need for Specialised Exchange Surfaces. 6 Cell Fractionation & Ultracentrifugation for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams. The Definition of a Gene. Revision notes on 4. 1 Energy for the CIE A Level Biology syllabus, written by the Biology experts at Save My Exams. The three-letter abbreviations indicate the specific amino acid (there are 20 commonly Carbohydrates. Naomi especially enjoys creating resources that enable students to build a solid understanding of subject content, while also connecting their knowledge with biology’s exciting, real-world applications. Haemoglobin is a globular protein which is an oxygen-carrying pigment found in vast quantities in red blood cells. 8 The Calvin Cycle for the CIE A Level Biology syllabus, written by the Biology experts at Save My Exams. 1. Independent assortment. 11. This energy is required: In anabolic reactions – building larger molecules from smaller molecules. 2 kg m⁻² (this means 0. The small volume means the diffusion distance to all organelles is short. Osmoregulation. 2 micrometres (µm) or 200 nm. Revision notes for the Cambridge O Level Biology syllabus, written by the Biology experts at Save My Exams. With Save My Exams, your revision resources are created by experienced educators and examiners who actually mark A Level exams, so you’ll know exactly what to revise and how to answer questions for maximum marks. A hormone called adrenaline can affect blood glucose concentration. The lac operon found in some bacteria is one of the most well-known of these. 1 Lipids for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams. 2 carbon (2C) Acetyl CoA enters the circular pathway from the link reaction in glucose metabolism. Revision notes on 12. 4 Effects of Humans on Ecosystems. The end of the axon, known as the axon terminal, contains many nerve endings. DNA of a cell determines the primary structure of a protein by instructing the cell to add certain amino acids in specific quantities in a certain sequence. Phenotypic variation can be divided into two types depending on how you are able to The lac operon. Student friendly model answers written by experienced teachers & examiners. The process of aerobic respiration using glucose can be split into four stages. There are different types of neurones. Primary succession occurs in a series of stages. The nucleotides found in DNA and RNA. Structural genes in prokaryotes can form an operon: a group or a cluster of genes that are controlled by the same promoter. 5 - 1. The cell surface membrane creates an enclosed space separating the internal cell environment from the external environment. These molecules are usually proteins. Each kidney contains thousands of tiny tubes, known as nephrons. The receptor cells send an impulse along the nerves and to the brain (coordinator) The brain sends an impulse to the wing muscles (effectors) of the red robin so it can fly away (response) The sequence of detection, coordination and action results in a The Krebs cycle (sometimes called the citric acid cycle) consists of a series of enzyme-controlled reactions. This term is used to avoid confusion between water concentration The Role of Adrenaline. Revision notes on 5. There are two types of lymphocytes (with different modes of Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning. Peripheral nervous system (PNS) – all of the nerves in the body. 3 Ecosystems & Biodiversity. 2 Phylogenetic Classification for the AQA A Level Biology syllabus, written by the Biology experts at Save My Exams. 2 Pyruvate (3C) molecules. Within the brain are different regions that carry out different functions. 0 µm in diameter. As the DNA base sequence determines the sequence of amino acids that make up a protein, mutations in a gene can sometimes Recognising ‘foreign’ cells and targeting any pathogenic cells, a process known as a specific immune response. 1 The Need for Transport Systems in Animals for the OCR A Level Biology syllabus, written by the Biology experts at Save My Exams. It results in the production of. This provides more space inside the cell for The fluid mosaic model of the membrane was first outlined in 1972 and it explains how biological molecules are arranged to form cell membranes. Synthesis of ATP in the mitochondria occurs during the last stage of respiration called oxidative phosphorylation. The liver is also connected directly to the gall bladder. Phylum: Angiospermae. Monohybrid inheritance is the inheritance of characteristics controlled by a single gene (mono = one) This can be determined using a genetic diagram known as a Punnett square. They are the site of aerobic respiration in eukaryotic cells. Red blood cells are biconcave discs, meaning that they are concave on both sides. DNA sequencing allows for the nucleotide base sequence of an organism's genetic material to be identified and recorded. It is possible to estimate the biomass of a group of organisms if you know the dry mass of a single organism. The Krebs cycle takes place in the matrix of the mitochondria. 2 Antibiotics. Biotechnology harnesses the processes in living organisms to. The current model for oxidative phosphorylation is the chemiosmotic theory. Firstly, seeds and spores that are carried by the wind land on the exposed rock and begin to grow. A vaccine is a suspension of antigens that are intentionally put into the body to induce artificial active immunity. Respiration occurs in all living organisms. This means their shape (as well as the shape of the active site of an enzyme) is determined by the complex tertiary structure of the protein that makes up the enzyme and is therefore highly specific. Genus: Canis. 19. For example, the Bornean orangutan ( Pongo pygmaeus) and Müller's gibbon ( Hylobates muelleri) live in the same area at the same Vaccines. Red blood cells do not contain a nucleus. It does this by binding to different receptors on the surface of liver cells that activate the same enzyme cascade that occurs when glucagon binds to its specific receptors. All molecules in this group contain C, H and O. This ability to recognise ‘foreign’ cells is made possible by specific molecules found on the surface of cells (and viral particles) that enable them to be identified by the body. To control a disease, it is very important to know what causes it (known A gene mutation is a change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide. Enzymes are globular proteins. 2 kg, we can say that the grass has a dry mass (i. A specific immune response where antibodies are released by plasma cells. Course-specific and 100% exam-aligned. Deoxygenated blood then leaves the liver in the hepatic vein and flows back to the heart. Cell-to-cell interactions. Progress tracking across 45+ topics & 3040+ questions, sorted by difficulty. 2 Biodiversity for the CIE A Level Biology syllabus, written by the Biology experts at Save My Exams. Proteins (including the enzyme reverse transcriptase) A protein coat (capsid) A viral envelope consisting of a lipid bilayer and glycoproteins. Intracellular membranes (internal membranes) form compartments within the cell, such as organelles (including the nucleus, mitochondria and RER) and vacuoles. Have simple growth requirements. those in the eye), decision-making centres in the central nervous system, and effectors such as muscles and glands. The cell cycle has three phases: interphase. Mutations occur continuously. They are thread-like structures of DNA, carrying genetic information in the form of genes. Neuromuscular junctions work in a very similar way to synapses. Revision notes on 7. From this the ratio of these combinations can be worked out. Jun 2, 2010 · Striated muscle contracts when it receives an impulse from a motor neurone via the neuromuscular junction. The Link reaction takes place in the matrix of the mitochondria. The large surface area allows for maximum absorption of nutrients and gases and secretion of waste products. ‘Catalysts’ because they speed up the rate of chemical reactions without being used up or undergoing permanent change. As these pioneer species die and decompose, the dead organic matter ( humus) forms a basic soil. Cholinergic Synapses. The Endocrine System. Sustainability is the ability of an ecosystem to maintain (or ideally increase) its biodiversity whilst simultaneously providing humans with the resources they need over a long period of time. 5. The ends of the two neurones, along with the synaptic cleft, form a synapse. Hypothetically there are two different forms (alleles) of that gene found in horses: A and a. Errors in the DNA often occur during DNA replication. Examples of simple reflex actions that are coordinated by these pathways are: Removing the hand rapidly from a sharp or hot object. A gene is a base sequence of DNA that codes for the amino acid sequence of a polypeptide or a functional RNA molecule. The Importance of Excretion. Meiosis produces daughter cells that are genetically different from each other and to the parent cell. This affects the shape and therefore the function of the protein. The Hibiscus rosa-sinensis (a colourful flowering plant) is another example of an organism in the eukarya domain. These cells are then grown in the laboratory and returned to the person by an injection into a vein. The classification of a Wolf. It allows us to make sense of our surroundings and respond to them and to coordinate and regulate body functions. Biodiversity looks at the range and variety of genes, species and habitats within a particular region. Revision notes on 8. The brain, alongside the spinal cord, is part of our central nervous system (CNS) The brain is made of billions of interconnected neurones and is responsible for controlling complex behaviours. These first species to colonise the new land (often moss and lichens) are known as pioneer species. Enzymes are essential for the process of digestion as Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning. Nucleotide structure table. Optical microscopes have a maximum resolution of around 0. The lac operon controls the production of the enzyme lactase (also called β-galactosidase) and two other structural proteins. Where two neurones meet, they do not actually come into physical contact with each other – a very small gap, known as the synaptic cleft, separates them. As the DNA base sequence determines the sequence of amino acids that make up a protein, mutations in a gene can sometimes lead to a change in the polypeptide that the gene codes for. Enzymes have an active site where specific substrates bind forming an enzyme-substrate complex. The active site of an enzyme has a specific shape to fit a specific substrate. It takes place in the cytoplasm of the cell and involves: Trapping glucose in the cell by phosphorylating the molecule. Revision notes on 6. Mitochondria are rod-shaped organelles 0. In the 1970s the chain termination method of sequencing was developed by Frederick Sanger and his colleagues. Bile salts (that help to digest fats) and bile pigments (a waste product The digestive system is connected to the circulatory system. Mutations occur continuously and spontaneously. The lipid bilayer is derived from the cell membrane of the host helper T cell that the particle escaped from. Save My Exams is the stress-free path to helping students study effectively and get higher grades than they ever thought possible. In animals, energy is required: A sudden movement by a crow (the stimulus) is detected by the receptors in the robin’s eye. They have a cell body that contains the nucleus and other cellular structures. Revision notes on 3. Neurones have a long fibre known as an axon. Focusing the eye on an object. They play an important part in the specific immune response. Therefore optical microscopes can be used to observe eukaryotic cells, their nuclei and possibly mitochondria and chloroplasts. It takes place at the inner mitochondrial membrane. ‘Biological’ because they function in living systems. Diffusion is a type of transportation that occurs across the cell membrane. The function of mitochondria is to synthesize ATP. Much less energy is released for each The examiner-written revision resources that improve your. The circulatory system in mammals is a well-studied example of a mass transport system; the one-way flow of blood Respiration is a chemical process that involves the breakdown of nutrient molecules (specifically glucose) in order to release the energy stored within the bonds of these molecules. 1 Energy Flow. Net gain 2 ATP. Single-celled organisms have a high SA:V ratio which allows for the exchange of substances to occur via simple diffusion. To move substances across the cell membrane (active transport) or to move substances within the cell. One of the genes for coat colour in horses is Agouti. Excretion is the process by which toxic waste products of metabolism and substances in excess of requirement are removed from the body. Worldwide the number of people infected with these diseases remains very high and these diseases pose serious public health problems now and for the foreseeable future. gv cz kg qd ku uc jk pt ys hh