CCEA GCSE Biology Unit 2 revision notes for 2016 specification. Includes detailed notes on: osmosis and plant transport, circulatory system, reproduction, fertility and contraception, DNA, cell division and genetics, variation and selection, and health, disease and defence mechanisms.
Biology 2
Osmosis and Plant Transport
Osmosis is the diffusion of water High Low
molecules from a dilute solution concentration concentration
(high concentration of water) to a e.g., bowl of of water
more concentrated solution (low water molecules
concentration of water) across a e.g., plant cell
selectively permeable membrane.
Large solute
When water moves into an animal molecules unable
cell, it stretches and gets bigger; if to pass through
this continues it will burst – lysis. membrane
Plant cell
Vacuole
Cell Water can move Small water molecules
Cytoplas Wall
m freely across the able to pass through
gradient membrane
Nucleu Cell
s Membrane
Chloropla Increases the Pressure created
st turgor by cell wall
Water moves Vacuole
pressure prevents too much
into cell expands
making it water entering and
turgid causing lysis
Plants use water for: Plasmolysis – too
Turgor much water moves
Transpiration B5 Potato Cylinder &
out of cell.
Transport of Visking tubing
minerals Cylinders in water or weak
Photosynthesis sucrose solution gain mass –
water moved in.
Transpiration Cylinders in strong sucrose
Transpiration is the evaporation of water from the spongy solution lose mass – water
mesophyll cells followed by the diffusion of water through the air moved out.
spaces and out of the stomata. Sucrose solution that causes no
Transpiration stream is important because it provides: change is the concentration
Leaves with a continuous supply of water (for equal to the potato cell.
photosynthesis). Visking tubing will gain mass as
Transport of minerals from roots to plant.
Support to plant cells.
Water for transpiration.
B6 Potometer & Washing Line
Method
Use a potometer to investigate factors
affecting the rate of water uptake.
Use washing line method to investigate
factors affecting the rate water loss.
Factor Effect on Why? How to change this
trans. factor
Surface Decrease Smaller leaves contain less Remove leaves
area stoma
Temperatu Increase High temp. increases rate of Use a heater
re evaporation
Wind Increase High wind speed increases rate Use a fan
speed of evaporation
Humidity Decrease High humidity will reduce Clear plastic bag over
evaporation plant
Light Decrease Darkness causes stomata to Use a lamp
intensity close
Circulatory System
, Functions of the circulatory system:
Transport – blood cells, glucose/amino acids, carbon dioxide, urea
Protect – against disease – lymphocytes and phagocytes
Blood Function Structure
Component
Red blood cells Carry oxygen Biconcave – large surface area
for diffusion of oxygen
Contains haemoglobin (contains
iron) to carry oxygen
No nucleus – more space
White blood Defend against disease Lymphocytes make antibodies
cells Phagocytes engulf and digest
Plasma Transport blood cells, food, urea, CO2, Yellow coloured liquid
hormones
Platelets Converts fibrinogen to fibrin – blood Cell fragments
clotting/scab
Blood Vessels
Artery usually deoxygented
Thick wall of muscle and elastic fibres to withstand high pressure.
Expand and recoil after each blood surge.
Small lumen
Away from the heart
Vein usually oxygenated
Thin wall of muscle and elastic fibres. Blood doesn’t surge through
veins.
Large lumen for less friction – faster travel of blood.
Has valves to prevent backflow. Glucose and oxygen carried in
Low pressure oxygenated blood is used for
respiration.
Into the heart
Capillary
Wall is one cell thick – allows
diffusion of substances
between blood and body
cells.
Large lumen relatively
From artery to vein
Pulmonar
y Vein
Pulmonar
y Artery
Aorta Right side pumps
Vena Cava deoxygenated blood to the
lungs.
Left side pumps oxygenated
blood to the organs of the
Ventricular walls thicker than atrial
Hepatic walls – ventricles must pump blood
Vein Hepatic further.
Artery Left ventricle wall is thicker than right
Hepatic one – left ventricle pumps blood all
Portal
Vein Mesenter around the body, whereas right only
ic Artery
The heart is a unidirectional pump.
Double circulatory system – blood
travels through the heart twice in one
circulation of the body.
Effects of exercise
Renal Renal
Vein Artery
Strengthens heart muscles
Increases cardiac output
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller StudiGuide. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for £6.19. You're not tied to anything after your purchase.
