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How much energy do you need?

The amount of energy you need to live depends on lots of different things. Some of these things you can change and some you can't. Males need to take in more energy than a female of the same age - unless the female is pregnant. If you are a teenager, you will need more energy than if you are in your 70s. Your food supplies energy to your muscles as they work. So the amount of exercise you do affects the amount of energy you need. If you do very little exercise, then you don't need as much food. The more you exercise the more food you need to take in. 

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The metabolic rate

Metabolic rate - The rate of chemical reactions in your cells.

Men generally have a higher metabolic rate than women. The proportion of muscle to fat in your body affects your metabolic rate. It is also affected by the amount of activity you do. Exercise increases your metabolic rate. 

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Balanced diet

A balanced diet contains:

Carbohydrates - Found in bread, potatoes and pasta - can be broked down to release energy.

Fibre - Found in cereal, fruit and veg - help us to digest food

Fat - Found in cheese, butter and oils - helps us to keep warm

Water - Found everywhere (natural substance) - Important for our chemical reactions

Protein - Found in meat, fish and cheese - important for growth and repair

Minerals - Found in fruit and vegetables - important in maintaing our body

Vitamins - Found in fruit and vegetables - vitamin C can help colds and helps boost our immune system

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Effects of obesity

Heart problems

Cholesterol problems

Fertility problems

Breathing problems


Muscle wastage


Skin sores

High blood pressure 

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Effects of starvation

Periods stop

Fertility issues

Constantly tired

Low energy

Low metabolism 

Mental disorders (Anorexia or Bulimia)

Loss of hair and nails break

Pale skin

Brittle bone syndrome

Poor immune system

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Malnourishment is when you get too much or too little of a component. 

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Cholesterol levels are affected by:

Balanced diets

High-fat foods



Statin - A drug given to peope to lower cholesterol

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Viruses and bacteria are micro-organisms that cause disease 

Pathogen - Microbes which cause disease 

Virus - need to get insise living cells to reproduce

Bacteria - Can divide every 20 minutes 

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Flu video

What speed is a sneeze? - 40mph

What is the first line of defence in the nose? - The line of hairs

What enables a virus to impersonate as a harmless protein to get inside a cell? - The protein spikes

How many viruses are made from a single throat cell? - 10,000

How many cells are infected with the virus within the 2 hours? - 5000

What do the killer cells do? - Patrol the body

What is the job of the macrophages? - Eat the debry

What are interleukins? - Chermical smoke signals

What effect do they have on the nerve cells? - They're hypersensitive 

What effect do they have on the natural thermostat? - Raises it

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Flu video (Part 2)

Where are the T cells and B cells found in the body? - In the lymph

What type of cell are the dendritic cells looking for? - The T cells

What causes glands to swell? - T cells

What do the T cells do? - Kill infected cells

What do the B cells produce? - Antibodies 

What is the role of the memory cells? - It recognises it next time

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The micro-ogranisms which cause infectious diseases are known as pathogens. Once viruses and bacteria get inside your body they reproduce rapidly. They damage your tissues and may produce toxins which cause the symptoms of disease

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Defence against disease

How do we pass on disease?

Coughings, animals, spitting, sex, cold, sneezing, insects, touch, HIV, saliva

How our body tries to defend us from these:

Skin is a barrier

Acid in the stomach kills bacteria

Nose hair and mucus 


Ear wax and hair


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White blood cells

Ingesting micro-organisms - White blood cells ingests pathogens, destroyin gthem and stopping them from making you ill

Producing antibodies - White blood cells create antibodies, these target particular bacteria or viruses and destroy them. You need a unique antibody to destroy each pathogen. Once your white blood cells have produced antibodies against a pathogen they can be made very quickly again.

Producing antitoxins- Some white blood cells produce antitoxins. These counteract the toxins released by the toxins. 

Pathogen - a bacterium, virus, or other microorganism that can cause disease

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Anti-biotic resistance

Antibiotic resistance happens when:

Antibiotics are over prescribed

You do not finish a course of antibiotics

How does antibiotic resistance bacteria arise?

Stop taking antibiotics before the end of the course

Those that surivive, mutate

That mutation spreads throughout the population

All bacteria are resistant to antibiotics 

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A vaccine - small amounts of dead or inactive pathogens are put into your body, often by injection

White blood cells making antibodies - The antigens in the vaccine stimulate your white blood cells into making antibodies. The antibodies destroy the antigens without any risk of you getting the disease 

White blood cells remembering antibodies - You are immune to future infections by the pathogen. That's because your body can respond rapidly and make the correct antibody as if you already had the diease 

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Five senses







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Stimulus - Receptor

Stimulus - Receptor

Light - Eye

Sound - Ear

Balance - Ear

Temperature - Skin

Pressure - Skin

Chemicals - Tongue and nose 

Stimulus - stimulus is something that causes a psychological response

Receptor - an organ or cell able to respond to light, heat, or other external stimulus and transmit a signal to a sensory nerve 

CNS - Central nervous system 

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Senses (Part 2)

Eyes - receptors sensitive to light

Ears - receptors sensitive to sound

Nose and tongue - receptors sensitive to chemicals for taste and smell

Skin - receptors sensitive to touch, pressure, pain and temperature changes

Ears - receptors sensitive to changes in positive for balance

Impulses - electrical signals to change what you're doing in your surroundings

Nervous system -

receptor --> sensory neuron --> coordinator (CNS) --> motor neuron --> effector 

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Reflex action

Reflex actions are a quick and automatic response

CNS - central nervous system - spine and brain needed for the cns

Reflex actions:

stimulus --> receptor --> sensory neurone --> relay neurone in cns --> motor neurone --> effector   --> response 


You touch something painful with your finger tip and you quickly flinch away

Skin --> sensory neurone --> CNS --> motor neurone --> arm and shoulder muscles 

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A junction between two neurons 

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  • Fertility drugs are used to make lots of eggs mature at the same time for collection
  • The eggs are collected and placed in a special solution in a petri dish
  • A sample of semen is collected
  • The eggs and sperm are mixed in a petri dish
  • The eggs are checked to make sure they have been fertilised and the early embryos are developing properly
  • When the fertilised eggs have formed tiny balls of cells, 1 or 2 of the tiny embryos are places in the uterus of the mother. Then, if it works, at least one baby will grow successfully 

IVF - In vitro fertilisation 

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What are hormones?

Hormones control the functions of your body organs. Chemical messages

How are they transported around the body?

Through the bloodstream

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Types of hormones

Oestrogen is produced in the ovaries. It stimulates the lining of the womb to build up ready for pregnancy. It also stimulates the pitutary gland to make another hormone gland known as LH

FSH is produced in the pitutary gland. It makes eggs mature in the ovaries, FSH also stimulates the ovaries to produce oestrogen

LH is produced in the pitutary gland. It stimulates the release of a mature egg from one of the ovaries in the middle of the menstrual cycle 

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Homeostasis is maintaining a constant internal environment 

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Plant hormones

Phototropism - Growth in the response to light

Shoots - positively phototropic

Roots - negatively phototropic

Geotropism/Gravitropism - Growth in the response to gravity

Shoots - negatively geotropic 

Roots - positively geotropic

Auxin - plant hormones which controls phototropism - found in the tip of the shoot. auxin moves to the shaded side to elongate and the shoot to bend towards the light 

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Drug - something that alters and chanfes your body at a chemical rate

Addiction to drugs - if you don't take the substance again once addicted you could get withdrawal symptoms. This could lead to: drowsiness, depression, anxiety, shaking, paranoia, moodswings and hallucinations 

Gateway drug - something that leads you to harder drugs. Cannabis is thought to lead you onto using heroine and crack etc. 

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Drug - something that alters and chanfes your body at a chemical rate

Addiction to drugs - if you don't take the substance again once addicted you could get withdrawal symptoms. This could lead to: drowsiness, depression, anxiety, shaking, paranoia, moodswings and hallucinations 

Gateway drug - something that leads you to harder drugs. Cannabis is thought to lead you onto using heroine and crack etc. 

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Pro Cannabis uses

Pro cannabis uses

Pain relief 


Helps alzheimers disease

To appear cool - peer pressure

Makes you high 

Helps you sleep 

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Con Cannabis uses

Con cannabis uses








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Drugs in sport

Some athletes use performance enhancing drugs to help them compete more successfully. Many use anabolic steroids which help them develop bigger muscles. 

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Advantages & Disadvantages of Drugs in sport

Advantages -

Makes you alert and on edge

Builds up muscle mass

Can compete with injury

Stimulates the body

Slows down heart rate

Disadvantages - 

Death risks Heart attacks or strokes Infertile

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Plant adaptations -

Edges of leaves have spikes

Tiny needles - spiny 

Spikes are sometimes made of silica to make them razor sharp

Animal adaptations -

Long necks to reach food high up

Elongated pupils

Big ears to hear predators

Swiel hips to stand up

Sensitive nose

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Surviving cold

Animals are relatively large for a larger surface area and to keep the volume ratio as small as possible to help them hold onto their body heat

They have small ears to reduce heat loss

Blubber - a thick layer of fat - to keep warm inside 

Fur coat to insulate an animal effectively

Fat layers provide a food supply - they can live off it in winter when there is no food

Camouflage so they can't be seen by prey

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Surviving heat

They get the water they need from food

They keep the same body temperature to help keep cool

They sweat to cool them down, but this means they lose water, which is a problem

More active early in the morning or late at night when the temperature is more comftorable 

They are quite small, so their surface area is large compared to their volume

They often have large, thin ears to increase their surface area of losing heat

They don't have much fur to keep cool 

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Pollution indicators and impact of change

Changing birds of britain -

Dartford Warbler - Breed in Southern Europe. As winters become warmer more and more warblers are breeding here

Bees - 

All around the world the honey bees are disappearing - colony collapse disorder. Bees either die or fail to return to the hive

Living causes of death - disease or parasite

Non-living causes - farmers spraying chemicals on plants, mobile phones could affect the navigation system of the bees 

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Pyramid of biomass

What does a pyramid of biomass show?

The amount of living matter in something

A pyramid of biomass represents the amount of energy at each stage. A pyramid of numbers represents the numbers of individuals 

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Decomposition is when dead or waste materials are broken down. Detritivores - Earthworms and woodlice - feed off detritus (dead organic materials) Decay conditions are usually moisture, warmth and plenty of oxygen

The decomposers are a group of micro-organisms which includes bacteria and fungi. They feed on waste droppings and dead organisms. They digest them and use some of the nutrients. They also release waste products which include carbon dioxide, water and minerals which plants can use

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The carbon cycle

The purpose of the carbon cycle is to recyle carbon 

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Gametes - sex cells

We have genes on our chromosones 

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Variation - similarities and differences 

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A-sexual reproduction only involves one parent. Advantage - no need to find a mate, can reproduce offspring quickly. Disadvantage - all offspring clones and a-sexual reproduction leads to decreased variation

Sexual reproduction is the fusion of two gametes. Advantage - increased variation. Disadvantage - need to find a mate 

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Genes, Chromosomes and DNA

Each cell of the body contains a structure called the nucleus 

This structure contains strands of genetic information, packaged into chromosones

These strands are made of a chemical called DNA

Sections of genetic material that control different characteristics are called genes

Smallest to largest

gene --> chromosone --> nucleus --> cell 

Alleles are different forms of the same gene

There are two chromosome 7s in a human nucleus, one from each parent

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Genetic engineering

What is GMO? - Genetically modified organisms 

Give an example - Glow in the dark cats

Advantages - they can make exactly the protein they need. improve the growth rates of plants and animals. GM food lasts longer. they are more complex proteins. they have the potential to save lives

Disadvantages - No one is sure about the long term effects. People are concerned about the effects of eating. GM crops are often infertile so farmers in poor countries have to buy new seeds every year. people want to mainipulate their children to have 'designer children' 

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Genetic engineering process

Human cell with insulin gene

Insuline gene cut from DNA using an enzyme

Insulin gene inserted into plasmid

Plasmid multiplies in bacterium and bacteria multiplies rapidly

Insulin harvested

Example of use: treating diabetes 

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What is a clone? - Offpsring produced by asexual reproduction which are identical to their parent organism

Cloning plant - Taking cutting, dip in root hormone powder and plant in soil

Cloning tissue - Tissue culture, mixture of plant hormones on agar plate. A few cells of the plant is placed on this

Embryo cloning - Animals. Taking an embryo and make it divide into several embryos. Place each embryo into a surrogate mother and all calves born are clones of each other 

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Charles Darwin - Theory of evolution by natural selection. 

The theory of evolution states that evolution happens by natural selection. Here are the key points:

Individuals in a species show a wide range of variation

This variation is because of differences in genes

Individuals with characteristics most suited to the environment are more likely to survive and reproduce

The genes that allowed the individuals to be successful are passed to the offspring in the next generation

Individuals that are poorly adapted to their environment are less likely to survive and reproduce. This means that their genes are less likely to be passed to the next generation. Given enough time, a species will gradually evolve

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Evolution (Part 2)

Jean-Baptiste Lamarck was a French scientist who developed an alternative theory of evolution at the beginning of the 19th century. His theory involved two ideas:

A characteristic which is used more and more by an organism becomesbigger and stronger, and one that is not used eventually disappears                       

Any feature of an organism that is improved through use is passed to its offspring

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