Biology | 9700

use Spearman’s rank correlation and Pearson’s linear correlation to analyse the relationships between two variables, including how biotic and abiotic factors affect the distribution and abundance of species (the formulae for these correlations will b describe the behaviour of chromosomes in plant and animal cells during meiosis and the associated behaviour of the nuclear envelope, the cell surface membrane and the spindle (names of the main stages of meiosis, but not the sub-divisions of prophase describe and use suitable methods to assess the distribution and abundance of organisms in an area, limited to frame quadrats, line transects, belt transects and mark-release-recapture using the Lincoln index (the formula for the Lincoln index will b explain that during photophosphorylation: energetic electrons release energy as they pass through the electron transport chain (details of carriers are not expected), the released energy is used to transfer protons across the thylakoid membrane, prot outline the three main stages of the Calvin cycle: rubisco catalyses the fixation of carbon dioxide by combination with a molecule of ribulose bisphosphate (RuBP), a 5C compound, to yield two molecules of glycerate 3-phosphate (GP), a 3C compound, GP describe the principles of cell signalling using the example of the control of blood glucose concentration by glucagon, limited to: binding of hormone to cell surface receptor causing conformational change, activation of G-protein leading to stimulat describe the roles of phospholipids, cholesterol, glycolipids, proteins and glycoproteins in cell surface membranes, with reference to stability, fluidity, permeability, transport (carrier proteins and channel proteins), cell signalling (cell surface explain that in non-cyclic photophosphorylation: photosystem I (PSI) and photosystem II (PSII) are both involved, photoactivation of chlorophyll occurs, the oxygen-evolving complex catalyses the photolysis of water, ATP and reduced NADP are synthesis recognise organelles and other cell structures found in eukaryotic cells and outline their structures and functions, limited to: cell surface membrane, nucleus, nuclear envelope and nucleolus, rough endoplasmic reticulum, smooth endoplasmic reticulum explain that during oxidative phosphorylation: hydrogen atoms split into protons and energetic electrons, energetic electrons release energy as they pass through the electron transport chain (details of carriers are not expected), the released energy Identify, in diagrams, photomicrographs and electron micrographs, the parts of a nephron and its associated blood vessels and structures, limited to: glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, c use the Hardy–Weinberg principle to calculate allele and genotype frequencies in populations and state the conditions when this principle can be applied (the two equations for the Hardy–Weinberg principle will be provided, as shown in the Mathematica explain that natural selection occurs because populations have the capacity to produce many offspring that compete for resources; in the ‘struggle for existence’, individuals that are best adapted are most likely to survive to reproduce and pass on t State where each of the four stages in aerobic respiration occurs in eukaryotic cells: glycolysis in the cytoplasm, link reaction in the mitochondrial matrix, Krebs cycle in the mitochondrial matrix, oxidative phosphorylation on the inner membrane of interpret and construct genetic diagrams, including Punnett squares, to explain and predict the results of dihybrid crosses that involve autosomal linkage and epistasis (knowledge of the expected ratios for different types of epistasis is not expecte describe the semi-conservative replication of DNA during the S phase of the cell cycle, including: the roles of DNA polymerase and DNA ligase (knowledge of other enzymes in DNA replication in cells and different types of DNA polymerase is not expecte explain that genetic engineering may help to solve the global demand for food by improving the quality and productivity of farmed animals and crop plants, using the examples of GM salmon, herbicide resistance in soybean and insect resistance in cotto describe the behaviour of chromosomes in plant and animal cells during the mitotic cell cycle and the associated behaviour of the nuclear envelope, the cell surface membrane and the spindle (names of the main stages of mitosis are expected: prophase, describe the structure of a DNA molecule as a double helix, including: the importance of complementary base pairing between the 5′ to 3′ strand and the 3′ to 5′ strand (antiparallel strands), differences in hydrogen bonding between C–G and A–T base p state the name and type of pathogen that causes each of the following diseases: cholera – caused by the bacterium Vibrio cholerae, malaria – caused by the protoctists Plasmodium falciparum, Plasmodium malariae, Plasmodium ovale and Plasmodium vivax, The microscope in cell studies - make temporary preparations of cellular material suitable for viewing with a light microscope The microscope in cell studies - draw cells from microscope slides and photomicrographs The microscope in cell studies - calculate magnifications of images and actual sizes of specimens from drawings, photomicrographs and electron micrographs (scanning and transmission) The microscope in cell studies - use an eyepiece graticule and stage micrometer scale to make measurements and use the appropriate units, millimetre (mm), micrometre (µm) and nanometre (nm) The microscope in cell studies - define resolution and magnification and explain the differences between these terms, with reference to light microscopy and electron microscopy Cells as the basic units of living organisms - describe and interpret photomicrographs, electron micrographs and drawings of typical plant and animal cells Cells as the basic units of living organisms - compare the structure of typical plant and animal cells Cells as the basic units of living organisms - state that cells use ATP from respiration for energy-requiring processes Cells as the basic units of living organisms - outline key structural features of a prokaryotic cell as found in a typical bacterium, including: unicellular, generally 1–5 µm diameter, peptidoglycan cell walls, circular DNA, 70S ribosomes, absence of organelles surrounded by double membranes Cells as the basic units of living organisms - compare the structure of a prokaryotic cell as found in a typical bacterium with the structures of typical eukaryotic cells in plants and animals Cells as the basic units of living organisms - state that all viruses are non-cellular structures with a nucleic acid core (either DNA or RNA) and a capsid made of protein, and that some viruses have an outer envelope made of phospholipids Testing for biological molecules - describe and carry out the Benedict’s test for reducing sugars, the iodine test for starch, the emulsion test for lipids and the biuret test for proteins Testing for biological molecules - describe and carry out a semi-quantitative Benedict’s test on a reducing sugar solution by standardising the test and using the results (time to first colour change or comparison to colour standards) to estimate the concentration Testing for biological molecules - describe and carry out a test to identify the presence of non-reducing sugars, using acid hydrolysis and Benedict’s solution Carbohydrates and lipids - describe and draw the ring forms of α-glucose and β-glucose Carbohydrates and lipids - define the terms monomer, polymer, macromolecule, monosaccharide, disaccharide and polysaccharide Carbohydrates and lipids - state the role of covalent bonds in joining smaller molecules together to form polymers Carbohydrates and lipids - state that glucose, fructose and maltose are reducing sugars and that sucrose is a non-reducing sugar Carbohydrates and lipids - describe the formation of a glycosidic bond by condensation, with reference to disaccharides, including sucrose, and polysaccharides Carbohydrates and lipids - describe the breakage of a glycosidic bond in polysaccharides and disaccharides by hydrolysis, with reference to the non-reducing sugar test Carbohydrates and lipids - describe the molecular structure of the polysaccharides starch (amylose and amylopectin) and glycogen and relate their structures to their functions in living organisms Carbohydrates and lipids - describe the molecular structure of the polysaccharide cellulose and outline how the arrangement of cellulose molecules contributes to the function of plant cell walls Carbohydrates and lipids - state that triglycerides are non-polar hydrophobic molecules and describe the molecular structure of triglycerides with reference to fatty acids (saturated and unsaturated), glycerol and the formation of ester bonds Carbohydrates and lipids - relate the molecular structure of triglycerides to their functions in living organisms Carbohydrates and lipids - describe the molecular structure of phospholipids with reference to their hydrophilic (polar) phosphate heads and hydrophobic (non-polar) fatty acid tails Proteins - describe and draw the general structure of an amino acid and the formation and breakage of a peptide bond Proteins - explain the meaning of the terms primary structure, secondary structure, tertiary structure and quaternary structure of proteins Proteins - describe the types of interaction that hold protein molecules in shape: hydrophobic interactions, hydrogen bonding, ionic bonding, covalent bonding, including disulfide bonds Proteins - state that globular proteins are generally soluble and have physiological roles and fibrous proteins are generally insoluble and have structural roles Proteins - describe the structure of a molecule of haemoglobin as an example of a globular protein, including the formation of its quaternary structure from two alpha (α) chains (α–globin), two beta (β) chains (β–globin) and a haem group Proteins - relate the structure of haemoglobin to its function, including the importance of iron in the haem group Proteins - describe the structure of a molecule of collagen as an example of a fibrous protein, and the arrangement of collagen molecules to form collagen fibres Proteins - relate the structures of collagen molecules and collagen fibres to their function Water - explain how hydrogen bonding occurs between water molecules and relate the properties of water to its roles in living organisms, limited to solvent action, high specific heat capacity and latent heat of vaporisation Mode of action of enzymes - state that enzymes are globular proteins that catalyse reactions inside cells (intracellular enzymes) or are secreted to catalyse reactions outside cells (extracellular enzymes) Mode of action of enzymes - explain the mode of action of enzymes in terms of an active site, enzyme–substrate complex, lowering of activation energy and enzyme specificity, including the lock-and-key hypothesis and the induced-fit hypothesis Mode of action of enzymes - investigate the progress of enzyme-catalysed reactions by measuring rates of formation of products using catalase and rates of disappearance of substrate using amylase Mode of action of enzymes - outline the use of a colorimeter for measuring the progress of enzyme-catalysed reactions that involve colour changes Factors that affect enzyme action - investigate and explain the effects of the following factors on the rate of enzyme-catalysed reactions: temperature, pH (using buffer solutions), enzyme concentration, substrate concentration, inhibitor concentration Factors that affect enzyme action - explain that the maximum rate of reaction (Vmax) is used to derive the Michaelis–Menten constant (Km), which is used to compare the affinity of different enzymes for their substrates Factors that affect enzyme action - explain the effects of reversible inhibitors, both competitive and non-competitive, on enzyme activity Factors that affect enzyme action - investigate the difference in activity between an enzyme immobilised in alginate and the same enzyme free in solution, and state the advantages of using immobilised enzymes Fluid mosaic membranes - describe the fluid mosaic model of membrane structure with reference to the hydrophobic and hydrophilic interactions that account for the formation of the phospholipid bilayer and the arrangement of proteins Fluid mosaic membranes - describe the arrangement of cholesterol, glycolipids and glycoproteins in cell surface membranes Fluid mosaic membranes - outline the main stages in the process of cell signalling leading to specific responses: secretion of specific chemicals (ligands) from cells, transport of ligands to target cells, binding of ligands to cell surface receptors on target cells Movement into and out of cells - describe and explain the processes of simple diffusion, facilitated diffusion, osmosis, active transport, endocytosis and exocytosis Movement into and out of cells - investigate simple diffusion and osmosis using plant tissue and non-living materials, including dialysis (Visking) tubing and agar Movement into and out of cells - illustrate the principle that surface area to volume ratios decrease with increasing size by calculating surface areas and volumes of simple 3-D shapes (as shown in the Mathematical requirements) Movement into and out of cells - investigate the effect of changing surface area to volume ratio on diffusion using agar blocks of different sizes Movement into and out of cells - investigate the effects of immersing plant tissues in solutions of different water potentials, using the results to estimate the water potential of the tissues Movement into and out of cells - explain the movement of water between cells and solutions in terms of water potential and explain the different effects of the movement of water on plant cells and animal cells (knowledge of solute potential and pressure potential is not expected) Replication and division of nuclei and cells - describe the structure of a chromosome, limited to: DNA, histone proteins, sister chromatids, centromere, telomeres Replication and division of nuclei and cells - explain the importance of mitosis in the production of genetically identical daughter cells during: growth of multicellular organisms, replacement of damaged or dead cells, repair of tissues by cell replacement, asexual reproduction Replication and division of nuclei and cells - outline the mitotic cell cycle, including: interphase (growth in G1 and G2 phases and DNA replication in S phase), mitosis, cytokinesis Replication and division of nuclei and cells - outline the role of telomeres in preventing the loss of genes from the ends of chromosomes during DNA replication Replication and division of nuclei and cells - outline the role of stem cells in cell replacement and tissue repair by mitosis Replication and division of nuclei and cells - explain how uncontrolled cell division can result in the formation of a tumour Chromosome behaviour in mitosis - interpret photomicrographs, diagrams and microscope slides of cells in different stages of the mitotic cell cycle and identify the main stages of mitosis Structure of nucleic acids and replication of DNA - describe the structure of nucleotides, including the phosphorylated nucleotide ATP (structural formulae are not expected) Structure of nucleic acids and replication of DNA - state that the bases adenine and guanine are purines with a double ring structure, and that the bases cytosine, thymine and uracil are pyrimidines with a single ring structure (structural formulae for bases are not expected) Structure of nucleic acids and replication of DNA - describe the structure of an RNA molecule, using the example of messenger RNA (mRNA) Protein synthesis - state that a polypeptide is coded for by a gene and that a gene is a sequence of nucleotides that forms part of a DNA molecule Protein synthesis - describe the principle of the universal genetic code in which different triplets of DNA bases either code for specific amino acids or correspond to start and stop codons Protein synthesis - describe how the information in DNA is used during transcription and translation to construct polypeptides, including the roles of: RNA polymerase, messenger RNA (mRNA), codons, transfer RNA (tRNA), anticodons, ribosomes Protein synthesis - state that the strand of a DNA molecule that is used in transcription is called the transcribed or template strand and that the other strand is called the non-transcribed strand Protein synthesis - explain that, in eukaryotes, the RNA molecule formed following transcription (primary transcript) is modified by the removal of non-coding sequences (introns) and the joining together of coding sequences (exons) to form mRNA Protein synthesis - state that a gene mutation is a change in the sequence of base pairs in a DNA molecule that may result in an altered polypeptide Protein synthesis - explain that a gene mutation is a result of substitution or deletion or insertion of nucleotides in DNA and outline how each of these types of mutation may affect the polypeptide produced Structure of transport tissues - draw plan diagrams of transverse sections of stems, roots and leaves of herbaceous dicotyledonous plants from microscope slides and photomicrographs Structure of transport tissues - describe the distribution of xylem and phloem in transverse sections of stems, roots and leaves of herbaceous dicotyledonous plants Structure of transport tissues - draw and label xylem vessel elements, phloem sieve tube elements and companion cells from microscope slides, photomicrographs and electron micrographs Structure of transport tissues - relate the structure of xylem vessel elements, phloem sieve tube elements and companion cells to their functions Transport mechanisms - state that some mineral ions and organic compounds can be transported within plants dissolved in water Transport mechanisms - describe the transport of water from the soil to the xylem through the: apoplast pathway, including reference to lignin and cellulose, symplast pathway, including reference to the endodermis, Casparian strip and suberin Transport mechanisms - explain that transpiration involves the evaporation of water from the internal surfaces of leaves followed by diffusion of water vapour to the atmosphere Transport mechanisms - explain how hydrogen bonding of water molecules is involved with movement of water in the xylem by cohesion-tension in transpiration pull and by adhesion to cellulose in cell walls Transport mechanisms - make annotated drawings of transverse sections of leaves from xerophytic plants to explain how they are adapted to reduce water loss by transpiration Transport mechanisms - state that assimilates dissolved in water, such as sucrose and amino acids, move from sources to sinks in phloem sieve tubes Transport mechanisms - explain how companion cells transfer assimilates to phloem sieve tubes, with reference to proton pumps and cotransporter proteins Transport mechanisms - explain mass flow in phloem sieve tubes down a hydrostatic pressure gradient from source to sink The circulatory system - state that the mammalian circulatory system is a closed double circulation consisting of a heart, blood and blood vessels including arteries, arterioles, capillaries, venules and veins The circulatory system - describe the functions of the main blood vessels of the pulmonary and systemic circulations, limited to pulmonary artery, pulmonary vein, aorta and vena cava The circulatory system - recognise arteries, veins and capillaries from microscope slides, photomicrographs and electron micrographs and make plan diagrams showing the structure of arteries and veins in transverse section (TS) and longitudinal section (LS) The circulatory system - explain how the structure of muscular arteries, elastic arteries, veins and capillaries are each related to their functions The circulatory system - recognise and draw red blood cells, monocytes, neutrophils and lymphocytes from microscope slides, photomicrographs and electron micrographs The circulatory system - state that water is the main component of blood and tissue fluid and relate the properties of water to its role in transport in mammals, limited to solvent action and high specific heat capacity The circulatory system - state the functions of tissue fluid and describe the formation of tissue fluid in a capillary network Transport of oxygen and carbon dioxide - describe the role of red blood cells in transporting oxygen and carbon dioxide with reference to the roles of: haemoglobin, carbonic anhydrase, the formation of haemoglobinic acid, the formation of carbaminohaemoglobin Transport of oxygen and carbon dioxide - describe the chloride shift and explain the importance of the chloride shift Transport of oxygen and carbon dioxide - describe the role of plasma in the transport of carbon dioxide Transport of oxygen and carbon dioxide - describe and explain the oxygen dissociation curve of adult haemoglobin Transport of oxygen and carbon dioxide - explain the importance of the oxygen dissociation curve at partial pressures of oxygen in the lungs and in respiring tissues Transport of oxygen and carbon dioxide - describe the Bohr shift and explain the importance of the Bohr shift The heart - describe the external and internal structure of the mammalian heart The heart - explain the differences in the thickness of the walls of the: atria and ventricles, left ventricle and right ventricle The heart - describe the cardiac cycle, with reference to the relationship between blood pressure changes during systole and diastole and the opening and closing of valves The heart - explain the roles of the sinoatrial node, the atrioventricular node and the Purkyne tissue in the cardiac cycle (knowledge of nervous and hormonal control is not expected) The gas exchange system - describe the structure of the human gas exchange system, limited to: lungs, trachea, bronchi, bronchioles, alveoli, capillary network The gas exchange system - describe the distribution in the gas exchange system of cartilage, ciliated epithelium, goblet cells, squamous epithelium of alveoli, smooth muscle and capillaries The gas exchange system - recognise cartilage, ciliated epithelium, goblet cells, squamous epithelium of alveoli, smooth muscle and capillaries in microscope slides, photomicrographs and electron micrographs The gas exchange system - recognise trachea, bronchi, bronchioles and alveoli in microscope slides, photomicrographs and electron micrographs and make plan diagrams of transverse sections of the walls of the trachea and bronchus The gas exchange system - describe the functions of ciliated epithelial cells, goblet cells and mucous glands in maintaining the health of the gas exchange system The gas exchange system - describe the functions of cartilage, smooth muscle, elastic fibres and squamous epithelium in the gas exchange system The gas exchange system - describe gas exchange between air in the alveoli and blood in the capillaries Infectious diseases - state that infectious diseases are caused by pathogens and are transmissible Infectious diseases - explain how cholera, malaria, TB and HIV are transmitted Infectious diseases - discuss the biological, social and economic factors that need to be considered in the prevention and control of cholera, malaria, TB and HIV (details of the life cycle of the malarial parasite are not expected) Antibiotics - outline how penicillin acts on bacteria and why antibiotics do not affect viruses Antibiotics - discuss the consequences of antibiotic resistance and the steps that can be taken to reduce its impact The immune system - describe the mode of action of phagocytes (macrophages and neutrophils) The immune system - explain what is meant by an antigen (see 4.1.3) and state the difference between self antigens and non-self antigens The immune system - describe the sequence of events that occurs during a primary immune response with reference to the roles of: macrophages, B-lymphocytes, including plasma cells, T-lymphocytes, limited to T-helper cells and T-killer cells The immune system - explain the role of memory cells in the secondary immune response and in long-term immunity Antibodies and vaccination - relate the molecular structure of antibodies to their functions Antibodies and vaccination - outline the hybridoma method for the production of monoclonal antibodies Antibodies and vaccination - outline the principles of using monoclonal antibodies in the diagnosis of disease and in the treatment of disease Antibodies and vaccination - describe the differences between active immunity and passive immunity and between natural immunity and artificial immunity Antibodies and vaccination - explain that vaccines contain antigens that stimulate immune responses to provide long-term immunity Antibodies and vaccination - explain how vaccination programmes can help to control the spread of infectious diseases Energy - outline the need for energy in living organisms, as illustrated by active transport, movement and anabolic reactions, such as those occurring in DNA replication and protein synthesis Energy - describe the features of ATP that make it suitable as the universal energy currency Energy - state that ATP is synthesised by: transfer of phosphate in substrate-linked reactions, chemiosmosis in membranes of mitochondria and chloroplasts Energy - explain the relative energy values of carbohydrates, lipids and proteins as respiratory substrates Energy - state that the respiratory quotient (RQ) is the ratio of the number of molecules of carbon dioxide produced to the number of molecules of oxygen taken in, as a result of respiration Energy - calculate RQ values of different respiratory substrates from equations for respiration Energy - describe and carry out investigations, using simple respirometers, to determine the RQ of germinating seeds or small invertebrates (e.g. blowfly larvae) Respiration - outline glycolysis as phosphorylation of glucose and the subsequent splitting of fructose 1,6-bisphosphate (6C) into two triose phosphate molecules (3C), which are then further oxidised to pyruvate (3C), with the production of ATP and reduced NAD Respiration - explain that, when oxygen is available, pyruvate enters mitochondria to take part in the link reaction Respiration - describe the link reaction, including the role of coenzyme A in the transfer of acetyl (2C) groups Respiration - outline the Krebs cycle, explaining that oxaloacetate (4C) acts as an acceptor of the 2C fragment from acetyl coenzyme A to form citrate (6C), which is converted back to oxaloacetate in a series of small steps Respiration - explain that reactions in the Krebs cycle involve decarboxylation and dehydrogenation and the reduction of the coenzymes NAD and FAD Respiration - describe the role of NAD and FAD in transferring hydrogen to carriers in the inner mitochondrial membrane Respiration - describe the relationship between the structure and function of mitochondria using diagrams and electron micrographs Respiration - outline respiration in anaerobic conditions in mammals (lactate fermentation) and in yeast cells (ethanol fermentation) Respiration - explain why the energy yield from respiration in aerobic conditions is much greater than the energy yield from respiration in anaerobic conditions (a detailed account of the total yield of ATP from the aerobic respiration of glucose is not expected) Respiration - explain how rice is adapted to grow with its roots submerged in water, limited to the development of aerenchyma in roots, ethanol fermentation in roots and faster growth of stems Respiration - describe and carry out investigations using redox indicators, including DCPIP and methylene blue, to determine the effects of temperature and substrate concentration on the rate of respiration of yeast Respiration - describe and carry out investigations using simple respirometers to determine the effect of temperature on the rate of respiration Photosynthesis as an energy transfer process - describe the relationship between the structure of chloroplasts, as shown in diagrams and electron micrographs, and their function Photosynthesis as an energy transfer process - explain that energy transferred as ATP and reduced NADP from the light-dependent stage is used during the light-independent stage (Calvin cycle) of photosynthesis to produce complex organic molecules Photosynthesis as an energy transfer process - state that within a chloroplast, the thylakoids (thylakoid membranes and thylakoid spaces), which occur in stacks called grana, are the site of the light-dependent stage and the stroma is the site of the light-independent stage Photosynthesis as an energy transfer process - describe the role of chloroplast pigments (chlorophyll a, chlorophyll b, carotene and xanthophyll) in light absorption in thylakoids Photosynthesis as an energy transfer process - interpret absorption spectra of chloroplast pigments and action spectra for photosynthesis Photosynthesis as an energy transfer process - describe and use chromatography to separate and identify chloroplast pigments (reference should be made to Rf values in identification of chloroplast pigments) Photosynthesis as an energy transfer process - state that cyclic photophosphorylation and non-cyclic photophosphorylation occur during the light-dependent stage of photosynthesis Photosynthesis as an energy transfer process - explain that in cyclic photophosphorylation: only photosystem I (PSI) is involved, photoactivation of chlorophyll occurs, ATP is synthesised Photosynthesis as an energy transfer process - state that Calvin cycle intermediates are used to produce other molecules, limited to GP to produce some amino acids and TP to produce carbohydrates, lipids and amino acids Investigation of limiting factors - state that light intensity, carbon dioxide concentration and temperature are examples of limiting factors of photosynthesis Investigation of limiting factors - explain the effects of changes in light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis Investigation of limiting factors - describe and carry out investigations using redox indicators, including DCPIP and methylene blue, and a suspension of chloroplasts to determine the effects of light intensity and light wavelength on the rate of photosynthesis Investigation of limiting factors - describe and carry out investigations using whole plants, including aquatic plants, to determine the effects of light intensity, carbon dioxide concentration and temperature on the rate of photosynthesis Homeostasis in mammals - explain what is meant by homeostasis and the importance of homeostasis in mammals Homeostasis in mammals - explain the principles of homeostasis in terms of internal and external stimuli, receptors, coordination systems (nervous system and endocrine system), effectors (muscles and glands) and negative feedback Homeostasis in mammals - state that urea is produced in the liver from the deamination of excess amino acids Homeostasis in mammals - describe the structure of the human kidney, limited to: fibrous capsule, cortex, medulla, renal pelvis, ureter, branches of the renal artery and renal vein Homeostasis in mammals - describe and explain the formation of urine in the nephron, limited to: the formation of glomerular filtrate by ultrafiltration in the Bowman’s capsule, selective reabsorption in the proximal convoluted tubule Homeostasis in mammals - relate the detailed structure of the Bowman’s capsule and proximal convoluted tubule to their functions in the formation of urine Homeostasis in mammals - describe the roles of the hypothalamus, posterior pituitary gland, antidiuretic hormone (ADH), aquaporins and collecting ducts in osmoregulation Homeostasis in mammals - explain how negative feedback control mechanisms regulate blood glucose concentration, with reference to the effects of insulin on muscle cells and liver cells and the effect of glucagon on liver cells Homeostasis in mammals - explain the principles of operation of test strips and biosensors for measuring the concentration of glucose in blood and urine, with reference to glucose oxidase and peroxidase enzymes Homeostasis in plants - explain that stomata respond to changes in environmental conditions by opening and closing and that regulation of stomatal aperture balances the need for carbon dioxide uptake by diffusion with the need to minimise water loss by transpiration Homeostasis in plants - explain that stomata have daily rhythms of opening and closing Homeostasis in plants - describe the structure and function of guard cells and explain the mechanism by which they open and close stomata Homeostasis in plants - describe the role of abscisic acid in the closure of stomata during times of water stress, including the role of calcium ions as a second messenger Control and coordination in mammals - describe the features of the endocrine system with reference to the hormones ADH, glucagon and insulin (see 14.1.8, 14.1.9 and 14.1.10) Control and coordination in mammals - compare the features of the nervous system and the endocrine system Control and coordination in mammals - describe the structure and function of a sensory neurone and a motor neurone and state that intermediate neurones connect sensory neurones and motor neurones Control and coordination in mammals - outline the role of sensory receptor cells in detecting stimuli and stimulating the transmission of impulses in sensory neurones Control and coordination in mammals - describe the sequence of events that results in an action potential in a sensory neurone, using a chemoreceptor cell in a human taste bud as an example Control and coordination in mammals - describe and explain changes to the membrane potential of neurones, including: how the resting potential is maintained, the events that occur during an action potential, how the resting potential is restored during the refractory period Control and coordination in mammals - describe and explain the rapid transmission of an impulse in a myelinated neurone with reference to saltatory conduction Control and coordination in mammals - explain the importance of the refractory period in determining the frequency of impulses Control and coordination in mammals - describe the structure of a cholinergic synapse and explain how it functions, including the role of calcium ions Control and coordination in mammals - describe the roles of neuromuscular junctions, the T-tubule system and sarcoplasmic reticulum in stimulating contraction in striated muscle Control and coordination in mammals - describe the ultrastructure of striated muscle with reference to sarcomere structure using electron micrographs and diagrams Control and coordination in mammals - explain the sliding filament model of muscular contraction including the roles of troponin, tropomyosin, calcium ions and ATP Control and coordination in plants - describe the rapid response of the Venus fly trap to stimulation of hairs on the lobes of modified leaves and explain how the closure of the trap is achieved Control and coordination in plants - explain the role of auxin in elongation growth by stimulating proton pumping to acidify cell walls Control and coordination in plants - describe the role of gibberellin in the germination of barley (see 16.3.4) Passage of information from parents to offspring - explain the meanings of the terms haploid (n) and diploid (2n) Passage of information from parents to offspring - explain what is meant by homologous pairs of chromosomes Passage of information from parents to offspring - explain the need for a reduction division during meiosis in the production of gametes Passage of information from parents to offspring - interpret photomicrographs and diagrams of cells in different stages of meiosis and identify the main stages of meiosis Passage of information from parents to offspring - explain that crossing over and random orientation (independent assortment) of pairs of homologous chromosomes and sister chromatids during meiosis produces genetically different gametes Passage of information from parents to offspring - explain that the random fusion of gametes at fertilisation produces genetically different individuals The roles of genes in determining the phenotype - explain the terms gene, locus, allele, dominant, recessive, codominant, linkage, test cross, F1, F2, phenotype, genotype, homozygous and heterozygous The roles of genes in determining the phenotype - interpret and construct genetic diagrams, including Punnett squares, to explain and predict the results of monohybrid crosses and dihybrid crosses that involve dominance, codominance, multiple alleles and sex linkage The roles of genes in determining the phenotype - interpret and construct genetic diagrams, including Punnett squares, to explain and predict the results of test crosses The roles of genes in determining the phenotype - use the chi-squared test to test the significance of differences between observed and expected results (the formula for the chi-squared test will be provided, as shown in the Mathematical requirements) The roles of genes in determining the phenotype - explain the relationship between genes, proteins and phenotype with respect to the: TYR gene, tyrosinase and albinism, HBB gene, haemoglobin and sickle cell anaemia, F8 gene, factor VIII and haemophilia, HTT gene, huntingtin and Huntington’s disease The roles of genes in determining the phenotype - explain the role of the dominant allele, Le, that codes for a functional enzyme in the gibberellin synthesis pathway, and the recessive allele, le, that codes for a non-functional enzyme Gene control - describe the differences between structural genes and regulatory genes and the differences between repressible enzymes and inducible enzymes Gene control - explain genetic control of protein production in a prokaryote using the lac operon (knowledge of the role of cAMP is not expected) Gene control - state that transcription factors are proteins that bind to DNA and are involved in the control of gene expression in eukaryotes by decreasing or increasing the rate of transcription Gene control - explain how gibberellin activates genes by causing the breakdown of DELLA protein repressors, which normally inhibit factors that promote transcription Variation - explain, with examples, that phenotypic variation is due to genetic factors or environmental factors or a combination of genetic and environmental factors Variation - explain what is meant by discontinuous variation and continuous variation Variation - explain the genetic basis of discontinuous variation and continuous variation Variation - use the t-test to compare the means of two different samples (the formula for the t-test will be provided, as shown in the Mathematical requirements) Natural and artificial selection - explain how environmental factors can act as stabilising, disruptive and directional forces of natural selection Natural and artificial selection - explain how selection, the founder effect and genetic drift, including the bottleneck effect, may affect allele frequencies in populations Natural and artificial selection - outline how bacteria become resistant to antibiotics as an example of natural selection Natural and artificial selection - describe the principles of selective breeding (artificial selection) Natural and artificial selection - outline the following examples of selective breeding: the introduction of disease resistance to varieties of wheat and rice, inbreeding and hybridisation to produce vigorous, uniform varieties of maize, improving the milk yield of dairy cattle Evolution - outline the theory of evolution as a process leading to the formation of new species from pre-existing species over time, as a result of changes to gene pools from generation to generation Evolution - discuss how DNA sequence data can show evolutionary relationships between species Evolution - explain how speciation may occur as a result of genetic isolation by: geographical separation (allopatric speciation), ecological and behavioural separation (sympatric speciation) Classification - discuss the meaning of the term species, limited to the biological species concept, morphological species concept and ecological species concept Classification - describe the classification of organisms into three domains: Archaea, Bacteria and Eukarya Classification - state that Archaea and Bacteria are prokaryotes and that there are differences between them, limited to differences in membrane lipids, ribosomal RNA and composition of cell walls Classification - describe the classification of organisms in the Eukarya domain into the taxonomic hierarchy of kingdom, phylum, class, order, family, genus and species Classification - outline the characteristic features of the kingdoms Protoctista, Fungi, Plantae and Animalia Classification - outline how viruses are classified, limited to the type of nucleic acid (RNA or DNA) and whether this is single stranded or double stranded Biodiversity - define the terms ecosystem and niche Biodiversity - explain that biodiversity can be assessed at different levels, including: the number and range of different ecosystems and habitats, the number of species and their relative abundance, the genetic variation within each species Biodiversity - explain the importance of random sampling in determining the biodiversity of an area Biodiversity - use Simpson’s index of diversity (D) to calculate the biodiversity of an area, and state the significance of different values of D (the formula for Simpson’s index of diversity will be provided, as shown in the Mathematical requirements) Conservation - explain why populations and species can become extinct as a result of: climate change, competition, hunting by humans, degradation and loss of habitats Conservation - outline reasons for the need to maintain biodiversity Conservation - outline the roles of zoos, botanic gardens, conserved areas (including national parks and marine parks), ‘frozen zoos’ and seed banks, in the conservation of endangered species Conservation - describe methods of assisted reproduction used in the conservation of endangered mammals, limited to IVF, embryo transfer and surrogacy Conservation - explain reasons for controlling invasive alien species Conservation - outline the role in conservation of the International Union for Conservation of Nature (IUCN) and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Principles of genetic technology - define the term recombinant DNA Principles of genetic technology - explain that genetic engineering is the deliberate manipulation of genetic material to modify specific characteristics of an organism and that this may involve transferring a gene into an organism so that the gene is expressed Principles of genetic technology - explain that genes to be transferred into an organism may be: extracted from the DNA of a donor organism, synthesised from the mRNA of a donor organism, synthesised chemically from nucleotides Principles of genetic technology - explain the roles of restriction endonucleases, DNA ligase, plasmids, DNA polymerase and reverse transcriptase in the transfer of a gene into an organism Principles of genetic technology - explain why a promoter may have to be transferred into an organism as well as the desired gene Principles of genetic technology - explain how gene expression may be confirmed by the use of marker genes coding for fluorescent products Principles of genetic technology - explain that gene editing is a form of genetic engineering involving the insertion, deletion or replacement of DNA at specific sites in the genome Principles of genetic technology - describe and explain the steps involved in the polymerase chain reaction (PCR) to clone and amplify DNA, including the role of Taq polymerase Principles of genetic technology - describe and explain how gel electrophoresis is used to separate DNA fragments of different lengths Principles of genetic technology - outline how microarrays are used in the analysis of genomes and in detecting mRNA in studies of gene expression Principles of genetic technology - outline the benefits of using databases that provide information about nucleotide sequences of genes and genomes, and amino acid sequences of proteins and protein structures Genetic technology applied to medicine - explain the advantages of using recombinant human proteins to treat disease, using the examples insulin, factor VIII and adenosine deaminase Genetic technology applied to medicine - outline the advantages of genetic screening, using the examples of breast cancer (BRCA1 and BRCA2), Huntington’s disease and cystic fibrosis Genetic technology applied to medicine - outline how genetic diseases can be treated with gene therapy, using the examples severe combined immunodeficiency (SCID) and inherited eye diseases Genetic technology applied to medicine - discuss the social and ethical considerations of using genetic screening and gene therapy in medicine Genetically modified organisms in agriculture - discuss the ethical and social implications of using genetically modified organisms (GMOs) in food production