SNAB EDEXCEL-- Unit 1 (Topics 1/2) Revision Notes

Written with spec- please be aware that core practicles for topic 2 are not present (cell membrane beetroot one and rennet/ enzyme one) will upload document of just core practicles later- just so you know sorry!

HideShow resource information
Preview of SNAB EDEXCEL-- Unit 1 (Topics 1/2) Revision Notes

First 430 words of the document:

H-Bonds creates adhesive affect- high mp/bp relative to similar sized
Excellent solvent- dipole allows ionic substances to be dissolved- polar
substances also dissolve
Carries non-polar substances as COLLOIDS (solute particles bigger than
Insoluble particles form EMULSIONS (droplets of one liquid held in another) or
SUSPENSIONS ­ (solid + liquid particles separate out if constantly moved)
High surface tension- like covered by skin- no interact between air and water
itself-h bonds pull down and together.
Amphoteric- acts as Ph buffer as is proton donor H+ or acceptor OH-
High latent heat of evaporation- evaporation takes a lot of energy so cools as
Thermally stable due to high specific heat capacity
Creates cohesion (important in plants section T4)
- higher metabolic rate of many mammals etc means that diffusion is too slow
to meet needs, as SA/V ratio is small- thus mass transport systems are used to
maximise efficiency. In some animals their needs are met by simple diffusion
such as amoeba with a large SA/V ratio diffusion is efficient and effective.
Plasma- main component largely water and dissolved substances
Erythrocytes- red blood cells- biconcave discs no nucleus more room for
haemoglobin and O2
Leukocytes- white blood cells- can squeeze and change shape, have nucleus +
colourless cytoplasm
Platelets- fragments of other cells, involved in clot formation.
Arteries- blood away from heart- to lungs = pulmonary artery to be
oxygenated- to body via aorta or head/neck via aorta and carotid arteries.
Small lumen, large amount collagen and elastic fibres to allow to return to
shape when expands. No valves, smooth endothelial lining- prevent friction.
Arteries most at risk from damage due to high blood pressure and recoil.
Veins- blood back towards heart- pulmonary vein from lungs (oxygenated)-
inferior vena cava and superior vena cava from body. Have valves to prevent
back flow as is at lower pressure than arteries. Large lumen to act as blood
reservoir and some but less elastic and collagen fibres.
Capillaries- network that links arteries and veins, 1 cell thick and very thin,
RBC pass through, nutrients out into network and waste (CO2 etc) returned to
red blood cell. Blood pressure low through network- blood flows from
arteries- arterioles to capillary network to venules and veins.

Other pages in this set

Page 2

Preview of page 2

Here's a taster:

Superior Vena Cava ­ vein-carries deoxygenated blood from the upper body to
right atrium.
Pulmonary Veins ­carries blood from the lungs to the left atrium of the heart
Right Atrium ­blood collection chamber of the heart, it has a thin walled
Left Atrium ­ this receives oxygenated blood from the left and right
pulmonary veins.
Right Ventricle ­ this receives blood from
the right atrium and pumps it in to the
pulmonary artery.…read more

Page 3

Preview of page 3

Here's a taster:

Controls heart- as nerves speed the heart or slow down- dependant on CO2
levels in blood- nerve control provides quick reactions- hormones also affect
heart rate but generally slower.
Feed myocardial (heart muscle) ­ above aortic valve from aorta so received
straight away and quickly.
Measured by SPHYGMOMANOMETER (automatic one or cuff + mercury
manometer and stethoscope)
BP = systolic bp / diastolic bp e.g.…read more

Page 4

Preview of page 4

Here's a taster:

Cascade =
Damage to lining- increased likelihood of clot- if clot occurs, inflammatory
response- cholesterol builds up = atheroma- build up of calcium, salts and
platelets = plaque formation- narrows artery- raises blood pressure- increased
likelihood of damage.
Clot can lead to aneurysm, plaque causes blood build up behind- artery bulges,
can rupture artery
Artherosclerosis- process as above but calcium plaque causes loss of elasticity
in artery walls- less able to cope with recoil damage more likely.…read more

Page 5

Preview of page 5

Here's a taster:

All composed of Carbon, Hydrogen and Oxygen.
Three main groups- monosaccharides, disaccharides and polysaccharides
Monosaccharides- single sugar molecules containing 1 Oxygen atom and 2
Hydrogen atoms for each Carbon.
(C H2 O)n (n= number of sugars) e.g. Triose (n=3) C3H6O3
Disaccharides are two joined monosacs.
Joined in a condensation reaction-H2O released
Link between two monosacs is covalent bond called glycosidic bond
(C6 H10 O5)n
Glucose+ Fructose = Sucrose (stored in plants e.g.…read more

Page 6

Preview of page 6

Here's a taster:

To be good store, bonds in carbohydrates need to be broken to release single
sugars for cells to use. Glycosidic bond between monosaccharides split by
hydrolysis- opposite condensation- water required/ added to bond. Hydrolysis
takes place in digestion/ in muscle and liver cells.
Fatty acids + glycerol (3 fatty acids : glycerol= triglyceride)
Act as energy source but also have functions such as protective around organs,
also waterproofing fur/ feathers, insulating properties- the fatty sheath
around nerves.…read more

Page 7

Preview of page 7

Here's a taster:

Filter fruit juice sample- add to burette, add to 1cm3 of DCPIP until DCPIP is
colourless- greater volume of liquid less vitamin C-repeat with other juices
ensure thorough cleaning
Problems can occur with judging when DCPIP has decolourised and potential to
read burette wrong- vitamin C containing juice added 1 drop at time- so only
to 1 drop accuracy.
Protein monomer is an amino acid.
Amino acids have carboxylic group, hydrogen atom, amino group (NH2) and
variable R group.…read more

Page 8

Preview of page 8

Here's a taster:

Glycerol and
phosphate= hydrophilic head, lipid
`tails' are hydrophobic fatty acids.
Chemical pass through layer by
carrier/channel proteins-
fat-soluble organic molecules and
small molecules e.g. water can pass
Cholesterol regulates fluidity.
Glycoproteins- function in cell signalling, recognition and binding
Carrier proteins- specific to molecules, transport via active transport. Channel
proteins- facilitated diffusion. Receptors bind to hormones.…read more

Page 9

Preview of page 9

Here's a taster:

DEOXYRIBOSE has OH, off carbon on bottom left pentagon corner, and H on
bottom right, RIBOSE has both OH.
Phosphate group- makes nucleic acids acidic
Sugar, Base and phosphate joined by CONDENSATION REACTIONS- loss 2 H20
Mononucleotides linked by condensation reaction- polynucleotide strands.
Sugar from one bonds to phosphate in another= hydroxyl group at one end and
phosphate at other.
RNA- forms singular polynuc. Strands- folded to shapes or remain thread.
DNA- two strands twisted around each other, one upside down.…read more

Page 10

Preview of page 10

Here's a taster:

When somatic (body) cells have mutations- specific enzymes
remove faulty area- acts as scissors.
Point mutation- change in gene itself- miscopying nucleotides
Chromosomal mutation- change in position of gene on chromosome
Gene deletion- loss of gene
Duplication- gene or gene sequence repeated
Inversion- genes wrong way round
Translocation- different genes in different chromosomes swapped/ muddled
Whole- chromosome mutation- entire chromosome lost- or duplicated
(Down's syndrome 3 copies chromosome 21 instead of 2)
Some mutations beneficial, some insignificant, some damaging.…read more



thanks alot , i really appreciate you work :)

Similar Biology resources:

See all Biology resources »See all resources »