Unit 1: Molecules, Diet, Transport and Health

1.1Water as a transport solvent

Understand the importance of water as a solvent in transport, including its dipole nature

1.2Monosaccharides, disaccharides and polysaccharides

(i) know the difference between monosaccharides, disaccharides and polysaccharides, including glycogen and starch (amylose and amylopectin) (ii) be able to relate the structures of monosaccharides, disaccharides and polysaccharides to their roles in providing and storing energy β-glucose and cellulose are not required in this topic.

1.3Core Practical 1 - reducing sugars and starch

CORE PRACTICAL 1 Use a semi-quantitative method with Benedict’s reagent to estimate the concentrations of reducing sugars and with iodine solution to estimate the concentrations of starch, using colour standards.

1.4Glycosidic bonds, condensation and hydrolysis

Know how monosaccharides (glucose, fructose and galactose) join together to form disaccharides (maltose, sucrose and lactose) and polysaccharides (glycogen, amylose and amylopectin) through condensation reactions forming glycosidic bonds, and how these can be split through hydrolysis reactions

1.5Triglycerides and saturated or unsaturated lipids

(i) know how a triglyceride is synthesised by the formation of ester bonds during condensation reactions between glycerol and three fatty acids (ii) know the differences between saturated and unsaturated lipids

1.6Need for hearts and circulation

Understand why many animals have a heart and circulation (mass transport to overcome the limitations of diffusion in meeting the requirements of organisms)

1.7Blood vessel structure and function

Understand how the structures of blood vessels (capillaries, arteries and veins) relate to their functions

1.8Cardiac cycle and mammalian heart function

Know the cardiac cycle (atrial systole, ventricular systole and cardiac diastole) and relate the structure and operation of the mammalian heart, including the major blood vessels, to its function Details of myogenic stimulation are not needed at IAS.

1.9Haemoglobin, oxygen dissociation and Bohr effect

(i) understand the role of haemoglobin in the transport of oxygen and carbon dioxide (ii) understand the oxygen dissociation curve of haemoglobin, the Bohr effect and the significance of the oxygen affinity of fetal haemoglobin compared with adult haemoglobin

1.10Atherosclerosis

Understand the course of events that leads to atherosclerosis (endothelial dysfunction, inflammatory response, plaque formation, raised blood pressure)

1.11Blood clotting and cardiovascular disease

Understand the blood clotting process (thromboplastin release, conversion of prothrombin to thrombin and fibrinogen to fibrin) and its role in cardiovascular disease (CVD)

1.12Cardiovascular disease risk factors

Know how factors such as genetics, diet, age, gender, high blood pressure, smoking and inactivity increase the risk of cardiovascular disease (CVD)

1.13Antioxidants and cardiovascular disease risk

Understand the link between dietary antioxidants and the risk of cardiovascular disease (CVD)

1.14Core Practical 2 - vitamin C content

CORE PRACTICAL 2 Investigate the vitamin C content of food and drink.

1.15Health risk data, correlation and causation

Be able to analyse and interpret quantitative data on illness and mortality rates to determine health risks, including distinguishing between correlation and causation and recognising conflicting evidence

1.16Study design for health risk factors

Be able to evaluate the design of studies used to determine health risk factors, including sample selection and sample size used to collect data that is both valid and reliable

1.17Perceived risk and actual risk

Understand why people’s perception of risks are often different from the actual risks, including underestimating and overestimating the risks due to diet and other lifestyle factors in the development of heart disease

1.18Cholesterol, HDL, LDL and CVD evidence

(i) be able to analyse data on the possible significance for health of blood cholesterol levels and levels of high-density lipoproteins (HDLs) and low-density lipoproteins (LDLs) (ii) know the evidence for a causal relationship between blood cholesterol levels (total cholesterol and LDL cholesterol) and cardiovascular disease (CVD)

1.19Scientific knowledge and CHD risk reduction

Understand how people use scientific knowledge about the effect of diet, including obesity indicators, such as body mass index and waist-to-hip ratio, exercise and smoking to reduce their risk of coronary heart disease

1.20Treatments for cardiovascular disease

Know the benefits and risks of treatments for cardiovascular disease (CVD) (antihypertensives, statins, anticoagulants and platelet inhibitors)

(i) know the properties of gas exchange surfaces in living organisms (large surface area to volume ratio, thickness of surface and difference in concentration) (ii) understand how the rate of diffusion is dependent on these properties and can be calculated using Fick’s Law of Diffusion (iii) understand how the structure of the mammalian lung is adapted for rapid gaseous exchange

(i) know the structure and properties of cell membranes (ii) understand how models such as the fluid mosaic model of membrane structure are interpretations of data used to develop scientific explanations of the structure and properties of cell membranes

CORE PRACTICAL 3 Investigate membrane properties including the effect of alcohol and temperature on membrane permeability.

Understand what is meant by osmosis in terms of the movement of free water molecules through a partially permeable membrane, down a water potential gradient

(i) understand what is meant by passive transport (diffusion, facilitated diffusion), active transport (including the role of ATP as an immediate source of energy), endocytosis and exocytosis (ii) understand the involvement of carrier and channel proteins in membrane transport

(i) know the basic structure of an amino acid Structures of specific amino acids are not required. (ii) understand the formation of polypeptides and proteins (amino acid monomers linked by condensation reactions to form peptide bonds) (iii) understand the significance of a protein’s primary structure in determining its secondary structure, three-dimensional structure and properties (globular and fibrous proteins and the types of bonds involved in its three-dimensional structure) (iv) know the molecular structure of a globular protein and a fibrous protein and understand how their structures relate to their functions (including haemoglobin and collagen)

(i) understand the mechanism of action and the specificity of enzymes in terms of their three-dimensional structure (ii) understand that enzymes are biological catalysts that reduce activation energy (iii) know that there are intracellular enzymes catalysing reactions inside cells and extracellular enzymes catalysing reactions outside cells

CORE PRACTICAL 4 Investigate the effect of temperature, pH, enzyme concentration and substrate concentration on the initial rate of enzyme-catalysed reactions.

(i) know the basic structure of mononucleotides (deoxyribose or ribose linked to a phosphate and a base, including thymine, uracil, adenine, cytosine or guanine) and the structures of DNA and RNA (polynucleotides composed of mononucleotides linked by condensation reactions to form phosphodiester bonds) (ii) know how complementary base pairing and the hydrogen bonding between two complementary strands are involved in the formation of the DNA double helix

(i) understand the process of DNA replication, including the role of DNA polymerase (ii) understand how Meselson and Stahl’s classic experiment provided new data that supported the accepted theory of replication of DNA and refuted competing theories

Understand the nature of the genetic code (triplet code, non-overlapping and degenerate)

Know that a gene is a sequence of bases on a DNA molecule that codes for a sequence of amino acids in a polypeptide chain

(i) understand the process of protein synthesis (transcription and translation), including the role of RNA polymerase, translation, messenger RNA, transfer RNA, ribosomes and the role of start and stop codons (ii) understand the roles of the DNA template (antisense) strand in transcription, codons on messenger RNA and anticodons on transfer RNA

(i) understand how errors in DNA replication can give rise to mutations (substitution, insertion and deletion of bases) (ii) know that some mutations will give rise to cancer or genetic disorders, but that many mutations will have no observable effect

(i) understand what is meant by the terms gene, allele, genotype, phenotype, recessive, dominant, codominance, homozygote and heterozygote (ii) understand patterns of inheritance, including the interpretation of genetic pedigree diagrams, in the context of monohybrid inheritance (iii) understand sex linkage on the X chromosome, including red-green colour blindness in humans

Understand how the expression of a gene mutation in people with cystic fibrosis impairs the functioning of the gaseous exchange, digestive and reproductive systems

(i) understand the uses of genetic screening, including the identification of carriers, pre-implantation genetic diagnosis (PGD) and prenatal testing, including amniocentesis and chorionic villus sampling (ii) understand the implications of prenatal genetic screening

Be able to identify and discuss the ethical and social issues relating to genetic screening from a range of ethical viewpoints, including religious, moral and social implications