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Summary A level Biology Edexcel A - Topic 1
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Summary Salters-Nuffield AS/A level Biology Student Book 1 + ActiveBook - Unit 1 - Lifestyle, Transport, Genes and Health
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Lecture notes Unit 1 - Lifestyle, Transport, Genes and Health Salters-Nuffield AS/A level Biology Student Book 1 + ActiveBook
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Presentation/Notes on Cardiovascular disease (A-Level Edexcel)
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Topic 1: Lifestyle, Health and RiskThis topic builds on students’ knowledge and understanding of the functioning of
the circulatory system and the importance of lifestyle choices to health. The role of
diet and other lifestyle factors in maintenance of good health is considered with
particular reference to the heart and circulation and to cardiovascular disease
(CVD). The structures and functions of some carbohydrates and lipids are also
detailed within this context. Ideas about correlation, causation and the concept of
risks to health are covered.
Students should be encouraged to carry out a range of practical experiments
related to this topic in order to develop their practical skills. In addition to the core
practicals detailed below, possible experiments include heart dissection to relate
heart structure to function, investigation of the structure blood vessels by
measuring the elastic recoil of arteries and veins and by examining slides of blood
vessels, measurement of blood pressure, and investigation of the hydrolysis of
disaccharides.
Opportunities for developing mathematical skills within this topic include calculating
probabilities, plotting two variables from experimental data, calculating % change,
substituting numerical values into algebraic equations using appropriate units for
physical quantities, constructing and interpreting frequency tables and diagrams,
bar charts and histograms, translating information between graphical, numerical
and algebraic forms and using scatter diagrams to identify a correlation between
two variables. (Please see Appendix 6: Mathematical skills and exemplifications for
further information.)
Students should:
1.1 Understand why many animals have a heart and circulation (mass transport to
overcome limitations of diffusion in meeting the requirements of organisms).
1.2 Understand the importance of water as a solvent in transport, including its
dipole nature.
1.3 Understand how the structures of blood vessels (capillaries, arteries and veins)
relate to their functions.
1.4 i) 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.
ii) Know how the relationship between heart structure and function can be
investigated practically.
1.5 Understand the course of events that leads to atherosclerosis (endothelial
dysfunction, inflammatory response, plaque formation, raised blood pressure).
1.6 Understand the blood-clotting process (thromboplastin release, conversion of
prothrombin to thrombin and fibrinogen to fibrin) and its role in cardiovascular
disease (CVD).
1.7 Know how factors such as genetics, diet, age, gender, high blood pressure,
smoking and inactivity increase the risk of cardiovascular disease (CVD).
1.8 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.
Pearson Edexcel Level 3 Advanced GCE in Biology A (Salters-Nuffield) 7
Specification – Issue 3 – July 2016 © Pearson Education Limited 2016
,Students should:
1.9 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.
1.10 Understand why people’s perceptions 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.
1.11 i) Be able to analyse data on energy budgets and diet.
ii) Understand the consequences of energy imbalance, including weight loss,
weight gain, and development of obesity.
1.12 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).
1.13 Know how monosaccharides join to form disaccharides (sucrose, lactose and
maltose) and polysaccharides (glycogen and amylose) through condensation
reactions forming glycosidic bonds, and how these can be split through
hydrolysis reactions.
1.14 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.
1.15 i) Be able to analyse and interpret 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).
1.16 Understand how people use scientific knowledge about the effects of diet,
including obesity indicators, body mass index and waist-to-hip ratio, exercise
and smoking to reduce their risk of coronary heart disease.
CORE PRACTICAL 1:
Investigate the effect of caffeine on heart rate in Daphnia.
1.17 Be able discuss the potential ethical issues regarding the use of invertebrates in
research.
CORE PRACTICAL 2:
Investigate the vitamin C content of food and drink.
1.18 Know the benefits and risks of treatments for cardiovascular disease (CVD)
(antihypertensives, statins, anticoagulants and platelet inhibitors).
8 Pearson Edexcel Level 3 Advanced GCE in Biology A (Salters-Nuffield)
Specification – Issue 3 – July 2016 © Pearson Education Limited 2016
, Topic One Biology
1.1 - Why Many Animals Have a Heart and Circulation
Animals have blood to transport substances and a heart to pump it, known as a circulatory system.
Tiny organisms like unicellular creatures move substances like 02, CO2 and digestive products via diffusion as its
fast enough to meet the organisms requirement / metabolic rate.
Complex multicellular organisms are too large for diffusion to move substances around their bodies quickly enough, so rely on a mass
transport system.
Mass flow = the movement of fluids down a pressure or temperature gradient,
Type of Explanation
circulatory system
Open – insects & Blood circulates in large open spaces
some other animal Heart pumps blood out into cavities surrounding the animals organs
groups Substances diffuse between the blood and cells
When heart muscle relaxes blood is drawn from cavity back to heart through small, valve ,openings
Closed - Blood is enclosed within tubes
Animals including Generating higher blood pressures as blood is forced along narrow channels instead of flowing into large cavities
Vertebrates Meaning blood travels faster so the system is more efficient at delivering substances around the body
Blood leaves heart under pressure flowing along arteries> arterioles (small arteries)> to capillaries
Capillaries come into contact with most cells in the body where substances are exchanged between the blood and cells
After passing along capillaries blood returns to heart by venules > to veins
Valves ensure blood flows in one direction
Single - Fish Heart pumps deoxygenated blood to the gills
Here gaseous exchange takes place
Diffusion of carbon dioxide from blood into water surrounding the gills, and diffusion of oxygen from the water into the blood
Blood leaving gills then flows around the rest of the body before returning to heart
Blood flows through the heart once for each complete circuit of the body
Double - Right ventricle of heart pumps deoxygenated blood to the lungs where it receives oxygen
Birds and mammals Oxygenated blood returns to the heart to be pumped a second time (by the left ventricle) out to the rest of the body
Blood flows through the heart twice for each complete circuit of the body
The heart gives the blood returning from lungs an extra boost reducing time taken for blood to circulate around whole body
This allows a high metabolic rate as oxygen and food required for metabolic processes are delivered more rapidly to cells
1.2 - Water as a Solvent in Transport
Water is a polar molecule= it has an unevenly distributed chemical charge
o The two hydrogens are pushed towards each other forming a V shaped molecule
o Hydrogen= slightly positive charge
o Oxygen= slightly negative charge (electrons more concentrated at this end)
Water is dipole so has a partial positive and negative charge making it cohesive (attraction between molecules of same type)
Hydrogen bonding holds the water molecules together
Solvent properties
Chemicals easily dissolve in water= biochemical reactions can occur in cytoplasm of cells
Dissolved substances can be transported around organisms
o E.g. in animals via the blood and lymph systems
o E.g. in plants via the xylem and phloem
Ionic substances like NaCl dissolve easily in water and get surrounded
Polar molecules dissolve easily in water molecules the polar groups e.g. –OH become surrounded by water and go into solution
Polar substances are hydrophilic= water attracting
Non-polar substances are hydrophilic, e.g. lipids and combine with proteins to form lipoproteins to allow transport in the blood
plasma is mainly water containing dissolved substances like glucose, 0 2, C02 urea, antibodies, hormones, enzymes, proteins
Thermal properties
A large amount of energy needed to break hydrogen bonds in water
A large input of energy causes a small increase in temperature so water warms up and
cools down slowly
Specific heat capacity is very high as to raise the temperature of 1cm 3 of water is 1oc
o This is due to the hydrogen bonds that must be broken
1.3 – Structure of Blood Vessels Relation to Function
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