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The conditions inside the body must be controlled within narrow limits. This is called homeostasis.
C02 it is a product of aerobic respiration removed through the lungs when we breathe out
urea it is produced in the liver when excess amino acids are broken down,the kidneys remove it from the blood and make urine, which is stored in the bladder temporarily
The pancreas monitors and controls the concentration of glucose in the blood. It produces a hormone called insulin. Insulin causes glucose to move from the blood into cells. It lowers the blood glucose concentration if it's too high.
two types of treatment for diabetes
Careful monitoring of food intake, with particular care taken over carbohydrates - which are digested into glucose.
Injecting insulin into the blood before meals. The extra insulin causes glucose to be taken up by the liver and other tissues. Cells get the glucose they need for respiration, and the blood glucose concentration stays normal.
Too hot - Sweat glands in the skin release more sweat. This evaporates, removing heat energy from the skin.Blood vessels leading to the skin capillaries become wider - they dilate - allowing more blood to flow through the skin, and more heat to be lost.When we get too cold:Muscles contract rapidly - we shiver. These contractions need energy from respiration, and some of this is released as heat.Blood vessels leading to the skin capillaries become narrower - they constrict - letting less blood flow through the skin conserving heat in the body.

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Know and understand that there are not only differences between different species of plants and animals but also between individuals of the same species.
There are clearly major differences between plants and animals, but there can be significant differences between members of the same animal/plant species or closely related species.
These differences are due partly to the information in the cells they have inherited from their parents and partly to the different environments in which the individuals live and grow.
Differences between members of the same species is called variation.
There are two types of variation, genetic variation and environmental variation.
Know and understand that asexual reproduction can be used to produce individuals that are genetically identical to their parent.
Appreciate that scientists can now add, remove or change genes to produce the plants and animals they want.
You are expected to use your skills, knowledge and understanding to interpret information about cloning techniques and genetic engineering techniques,
In the exam you may be given data to work from,
make informed judgements about the economic, social and ethical issues concerning cloning and genetic engineering, including genetically modified (GM) crops.

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Fitness, blood pressure, smoking

Measure fitness by strength, stamina – endurance or staying power, flexibility, agility – how , speed, cardiovascular efficiency – health is the amount of freedom from disease.

systolic pressure - the higher measurement when the heart beats, pushing blood through the arteries, and diastolic pressure - the lower measurement when the heart rests between beats
Arteries carry blood away from the heart. Blood in the arteries is under pressure because of the contractions of the heart muscles. This allows the blood to reach all parts of the bod
A young, fit person should have a blood pressure of about 120 over 70, which means their systolic pressure is 120 mmHg and their diastolic pressure 70 mmHg.
increase blood pressure, by: smoking, being overweight, drinking a lot of alcohol, stress.
High blood pressure can cause: kidney damage, burst blood vessels, damage to the brain, including strokes.
Cigarettes contain about 4,000 different chemical, nicotine - the addictive substance in tobacco smoke, carbon monoxide.
Nicotine itself increases the heart rate and carbon monoxide reduces the oxygen-carrying capacity of the blood. It combines with haemoglobin in red blood cells, preventing oxygen combining with the haemoglobin.
Heart attacks; fatty deposits build up in the coronary arteries, a blood clot can form on a fatty deposit, the blood clot can block a coronary artery, some heart muscle cells do not get the oxygen and nutrients they need and these cells start to die.

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The eye

Cornea Front part of the tough outer coat, the sclera. It is convex and transparent. refracts light - bends it as it enters the eye
Iris Pigmented - decides the colour of your eyes - so light cannot pass through. Its muscles contract and relax to alter the size of its central hole or pupil. controls how much light enters the pupil
Lens Transparent, , flexible disc behind the iris attached by the suspensory ligaments to the ciliary muscles. focuses light onto the retina
Retina The lining of the back of eye containing two types of photoreceptor cells - rods - sensitive to dim light and black and white - and cones - sensitive to colour. A small area called the fovea in the middle of the retina has many more cones than rods. contains the light receptors
Optic nerve Bundle of sensory neurones at back of eye. carries impulses from the eye to the brain
Light passes through the eyeball to the retina. It is refracted by the cornea and lens, so that the light is brought to a focus on the retina.
Because our eyes sit side by side, each eye captures a slightly different view. This is called stereoscopic vision. When signals from the two eyes reach the brain, they are superimposed and processed into a single picture with depth. As a result, we get a 3D picture and can judge distances well.Most birds have monocular vision their eyes are on each side of their head. This gives them a greater field of view, which is useful for spotting predators. However, they have poor depth perception.

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Neurones and reflexes

The main parts of the nervous system are the central nervous system - the CNS - the brain and spinal cord - and the peripheral nervous system. Nerve impulses are mainly electrical and carried in nerve cells, or neurones.

The sheath acts as an insulator - rather like the plastic coating of an electrical wire. Neurones are adapted to their function by being long, so that they communicate with distant parts of the body. They also have branched endings called dendrites. These connect with many other neurones. The gap between two neurones is called a synapse. The nerve impulse passes across this gap through chemicals that diffuse across the gap. The electrical signal travels along an axon and triggers the release of chemical transmitters from the nerve ending of the first neurone. These diffuse across the gap and make the second neurone re-transmit the electrical signal. REFLEXES.

When a receptor is stimulated, it sends a signal to the central nervous system, where the brain co-ordinates the response. But sometimes a very quick response is needed, one that does not need the involvement of the brain.

receptor detects a stimulus - change in the environment
sensory neurone sends signal to relay neurone
motor neurone sends signal to effector
effector produces a response

The way the iris in our eye adjusts the size of the pupil in response extreme light is a reflex action.

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Eating healthy, diets

Carbohydrates and fats are high energy sources. Protein, meanwhile, is needed for growth and repair. Protein deficiency leads to diseases such as kwashiorkor.

carbohydrates simple sugars such as glucose high energy source

fats fatty acids and glycerol high energy source

proteins amino acids growth and repair

Balanced diet includes;

minerals, like iron, to make haemoglobin

vitamins, such as vitamin C, which prevents a disease called scurvy

fibre, which prevents constipation


BMI = mass in kg ÷ (height in m)2

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scurvy is caused by vitamin C deficiency

anaemia is caused by iron deficiency

diabetes and cancer are disorders of the body.

A cancer happens when cells begin to divide out of control. They form tumours that can sometimes be felt as an unusual lump in the body.

Diet and lifestyle can increase the risk of developing certain cancers. For example:

smoking increases the risk of lung cancer

using sunscreen reduces the risk of skin cancer

eating more fruit and vegetables reduces the risk of bowel

benign tumours grow slowly and are usually harmless – warts are benign tumours

malignant tumours often grow more quickly and may spread throughout the body.

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