The retina is the light sensitive layer which is responsible for 'seeing' light. The retina is
composed of two types of light sensitive cells.
These cells are capable of seeing only different degree's of light intensity and cannot
Unit 10 : Gas Exchange
The lungs are located in the chest inside a lubricated membrane called the pleural
membrane.This allows the lungs to move freely inside the pleural cavity. The lungs
are connected to the outside via the trachea (windpipe). The trach
Active transport in the membrane
Conduction of nerve impulses
This is the breakdown of glucose without using oxygen. In this process the energy produced is
relatively small and the product is va
Blood travels via arteries until it reaches smaller vessels called capillaries. It is here that
materials are exchanged between blood and the tissue cells.
1. The blood enters a capillary bed. These vessels are very leaky and are only wi
White blood cells and immunity
There are two types of white blood cell, phagocytes and lymphocytes. Their role in defence
against disease is different.
Phagocytes wander around the blood looking for foreign bodies. When these are encountered a
W hen we cut ourselves we not only lose blood but we also make it easier for bacteria to get
inside our bodies. Therefore the body must stop the flow of blood and block the breach in the
skin to prevent blood loss and infection. For this to be ef
Reasons for CHD:
Fatty diet: eating too much fats.
Smoking: it contains nicotine which increases the rate of fat deposition
Stress and lack of exercise
Blood vessels are tubes, which carry the blood around the body. There are different types o
1) The atria contract, forcing blood into the ventricles, which fill.
2) Sphincter (ring) muscles closing off the venae cavae and the
pulmonary veins prevents backflow from the atria into the main
1) The ventricle
The heart is really two pumps stuck together. There are two chambers to each side of the
heart. The first chamber is called the atrium and is the smaller of the two chambers. The
larger one is called the ventricle. This chamber is the more powerful of the
Unit 9: Transport in humans
Transportation in humans is done by the circulatory system which involves blood being
pumped around the body by the heart. Humans have a double circulatory system which
means that the blood is pumped twice around the body once
The rate of transpiration depends on:
Temperature: the higher the temperature the faster the uptake
Humidity: The higher the humidity the lower the uptake
Air current: The higher the air current the higher the uptake
W ater availability in soil
The diaphragm and breathing
W hen we breathe in the diaphragm muscle contracts, pulling the sheet down. The
intercostal muscles in between the ribs also contract which pulls the whole ribcage
upwards and outwards. These together increase the volume of the
Smoking causes a number of diseases, some of them life threatening.
Nicotine This is the substance which makes smoking addictive. Nicotine is a
stimulant which can make the heart beat faster and increase the amount of
adrenaline released. It also
Unit 11 :Excretion
It is the removal of waste products of metabolism and substances in excess of
requirements from organisms. (dont mix it with egesting).
Organs that excrete:
The urinary system consists of two kidneys, two ureters a
bladder and a urethra
Unit 14 : The Eye
Sclera: a tough coat that protects the eye from the inside.
Choroid: A layer that absorbs light so no internal reflection happens
Retina: contains light sensitive cells.
Yellow spot: The highest concentration of rods and cones
The synapse is a junction where two or more nerve cells meet. The synapse allows the
nerve cells to pass on their electrical impulse to another cell. The synapse is also a way
of controlling the direction in which impulses travel. They can only tr
These neurons carry impulses away from the CNS towards effecter organs like muscles
or glands. These cells have very long axons at the end of which are motor end plates
where the nerve cell can stimulate the effecter organ.
The reflex arc
Interneuron (relay neurone):
Relays message from sensory neurone to motor neurone
Make up the brain and spinal cord
The sensory neuron gathers information from the senses and passes it on to the central
nervous system (CNS). It is attached
Info about neurons
Made up of a bundle of axons which are surrounded by myelin sheath.
A synapse joins two neurons together. It contains chemical messages.
Have branched ends that receives impulses.
Efferent Neuron Moving toward a central o
Unit 13 :The nervous system
Any nervous action is a result of a stimulus.
is any change either internal or external which leads to a response. This could be
a noise, smell or the changes in blood sugar level.
is a specialized cell wh
Blood sugar levels should be maintained. This is how it is maintained:
Blood sugar is too high
Messages sent to pancreas to produce insulin
Insulin converts glucose to glycogen
Sugar level maintained
Message sent to pancreases to stop insulin.
Unit 12: Homeostasis and
IT is the maintenance of the conditions of the internal body environment. The
conditions are maintained by hormones which are secreted by some organs.
Hormones are chemical messages and chemicals released from an endocrin
This is when a kidney of a person faiols then he has to either get a transplant or get
This is when the diseased kidney is surgically removed and replaced by a fully
functioning kidney from a deceased or a live donor. I
The kidneys have four functions:
Regulation of blood water levels
Reabsorption of useful substances into the blood
Adjustment of the levels of salts and ions in the blood
Excretion of urea and other metabolic wastes
A nephron is a the smallest unit that f
Unit 8: Transport in plants
Transport is the movment or flow of different substances within a living organism. The
transport system in plants is the vascular bundles (xylem and phloem)
W ater enters the plant via the roots by osmosis they are then carried
Adaptation to insects on life on lands
Body covered in flexible chateaus exoskeleton
1 or 2 pair of wings
Joined legs for quick movement
Can live on all food materials
Can camouflage to hide from enemies
Chordates (or Vertebrates)
Chordates are vertebrate
There are two main groups in the animal kingdom. The chordates and the invertebrates. The
invertebrates consist of Nematodes, Annelids, Molluscs and Arthropods.
Comparison between Annelids, Nematodes and Molluscs.
Arthropods are divided into insec
Darwin's Conversion" The
FRANK J. SULLOWAY
Department of Psychology and Social Relations
Cambridge, Massachusetts 02138
I feel not a shade of surprise at your entirely rejecting m y views:
m y surprise is
Lab Activity: Measuring with Metric
The purpose of this activity is to practice using the metric system. To conduct a scientific investigation, a
researcher must be able to make accurate measurements. In todays exer
for High School Sciences
learn about new advances in
see how this technology applies to the
Types of Tissue Culture
The types of tissue culture can be grouped by
the structures formed in culture.
Hartmann and Kesters Plant Propagation, Principles and Practices 8th ed. Hudson Hartman