as biology unit 1

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  • Created on: 04-05-13 17:54
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Lifestyle, health and risk- introducing biological molecules
Carbon, hydrogen and oxygen make up carbohydrates and proteins are made up of amino
acids which are made up carbon, hydrogen, oxygen and nitrogen
In most living things, water takes up about 65-95% of its mass
Water is made up of oxygen and hydrogen (attached to each other using covalent bonding
(the sharing of electrons) and there is a slightly negative charge across the oxygen atom and
there is a slightly positive charge across the hydrogen atom. Because of this, the water is a
polar molecule)
Water molecules attract each other using the hydrogen bonds (from hydrogen to oxygen
and it's a relatively weak bond)
Water is a powerful solvent for polar substances. These include:
Ionic substances like sodium chloride- all cations (positively charged ions) and anions
(negatively charged anions) become surrounded by a shell of orientated water
Carbon-containing organic molecules with ionised groups e.g. carboxyl group- soluble
organic molecules like sugars dissolve in water due to the formation of hydrogen bonds
with their slightly charged hydroxyl groups
Once these substances have dissolved, molecules of the substance (solute) are free to
move around the water (solvent) and as a result, are more chemically reactive than when in
the undissolved solid
The carbon of organic compounds
The majority of carbon compounds have carbon mixed up with other atoms and they are
known as organic molecules
Carbon atoms can react with each other to form extended chains (can be shown in the
skeleton model) and can be represented in different models e.g. tetrahedron, ball and
spring, space filling etc.
Carbohydrates contain 3 elements- carbon, hydrogen and oxygen with hydrogen and
oxygen always present from 2:1
Are soluble in water and taste sweet. One type of monosaccharide is glucose which is
important because:
All green leaves manufacture glucose using light energy
Our bodies transport glucose in the blood
All cells use glucose in respiration- it is one of the respectitory substrates
In cells and organisms, glucose is the building blocks for larger molecules
Glucose has a molecular formula of C6H12O6
Glucose can't exist in linear form because each carbon atom arranges its 4 bonds into a
tetrahedron so the molecules can't be flat
Compounds that have the same molecular formula but different arrangement are called

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Glucose, fructose and galactose are examples of hexose sugars commonly occurring in cells
and organisms.
Disaccharides are carbohydrates made of 2 monosaccharides combined together e.g.
When 2 monosaccharides combine, water forms and condensation reaction occurs and a
glycosidic linkage occurs.…read more

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A glycerol and fatty acid makes a monoglyceride that has an ester linkage which with a
condensation reaction gives a diglyceride and another condensation reaction makes a
Oils have double bonds with kinks to stop them from packing together (unsaturated) unlike
animal fats which have single bonds that are solid at room temperature (saturated).
Polyunsaturated fats have just one double bond and are just a mix of saturated and
unsaturated fats- but are usually liquid at room temperature.…read more

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White cells Lymphocytes have major roles in the immune system, including forming antibodies
phagocytes ingest bacteria or cell fragments
Platlets Involved in the blood clotting mechanism
The plumbing of the circulatory system- arteries, veins and capillaries
3 types of vessel in the circulatory system are arteries, veins and capillaries
Both arteries and veins have strong, elastic walls ­ which come from the collagen fibres and
the elasticity comes from the elastic fibres and smooth elastic fibres
The walls of capillaries has endothelium only and branch…read more

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The cardiac cycle
Atrial systole
1. Atrium muscles contract, pushing blood past the bicuspid valve into the ventricle
2. Atrium muscles relax
Ventricular systole atrial diastole
3. Ventricle muscles contract, causing blood pressure to close the bicuspid valve and open the
semi-lunar valves, forcing the blood out of the aorta
4. Ventricle and atrium muscles relax, while the pressure of the blood in the aorta causes the
semi lunar valves to shut
Atrial + ventricular diastole
5.…read more

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Systolic Diastoli Condition Response
120 80 optimum
120-130 80-85 normal Biennial checks
130-139 85-89 High-normal Annual checks
140-159 90-99 Stage 1 hypertension Check in 2 months
160-179 100-109 Moderate (stage 2) hypertension Treatment essential
180-209 110-119 Severe (stage 3) hypertension Treatment essential
209-210 120 Very severe (stage 4) Treatment essential
Exchange in the tissues-formation of tissue fluid
Tissue fluid assists the delivery of nutrients to cells and the removal of waste products
The walls of capillaries are permeable to many components of the…read more

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Hypertension- means persistent high blood pressure and is known as the silent killer. It
causes the heart to increase its workload and increases the risk of athecolorisis and damages
blood vessels
Smoking- the habit of cigarette smoking generates the greatest risk o fatal health. Carbon
Monoxide combines with haemoglobin in red cells reducing the ability of the blood to
transport oxygen to all respiring cells and nicotine increases adrenaline production and this
triggers the heart rate and causes the arteries to contract.…read more

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Blockers- substances taken daily to reduce blood pressure by reducing heart rate. The
heart rate is caused to beat less frequently
Calcium channel blockers- substances that work by widening blood vessels so allowing more
blood to flow at reduced pressure.…read more

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How physically active we are in work and leisure- additional energy is needed for
physical activity
Our age and the amount of growth and repair work the body has to support- the rapid
growth that occurs in adolescence makes an additional demand of 8kJ per hour
Our sex- females require less energy than males unless if pregnant or breastfeeding.…read more

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A cohort is a group of people who share a common charactestics or experience within a
defined time period e.g. in Inuit people, they have a rich diet of oily fish
Randomised controlled trials (RCT) are a method that's common in evaluating the
effectiveness of medicines by giving treatments at random- some patients receive the real
drug and others receive the placebo and both are treated identically.…read more


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