HEALTHY EATING- Food
It is essential for life...
- To ensure us with a 'fuel' for energy
- To provide materials for growth and repair
- To keep our bodies healthy- ensuring an immune response.
Everyone's dietary needs:
- Lipids/ fats
A balanced diet- a diet that rovides all of the components required and in the correct proportions to keep you healthy.
Carbohydrate- is the bodies main 'fuel' for suplying cells with energy. Cells release this energy by using sugars, such as glucose, in the process respiration.
Protein- is used to make comounds in the body, e.g. muscle, bone, hair, enzymes and antibodies. Hence is required for growth and repair.
Fat/lipids- Is an important component of cell structure. It is deposited under the skin to provide insulation. It is a long-term energy store.
Water- Is required to dissolve some chemicals to allow reactions. It helps tos transport substances around the body and is useful in sweat to cool down the body.
Fibre- It provides bulk to the food to help the movement of food through the digestive system by the process peristalsis.
Minerals- These are required in small amounts to keep the body healthy and prevent deficiency disease, such as rickets and anaemia.
Vitamins- Theses are required in small amounts to keep the body healthy and prevent deficiency disease, such as scurvy and night blindness.
- Elements: carbon, hydrogen and oxygen.
- Fats and oils are known as lipids
- The chemical building blocks of fat are two molecules called glycerol and fatty acids. A single molecule of glycerol is joined to 3 fatty acids
- Function: -an essential part of all cells -a long-term energy store -acts as insulation -fat around vital organs protects them from mechanical damage.
- Good sources: -meat -butter -cheese -milk -eggs -oily fish
- Plant oils include: -olive oil -corn oil -rapeseed oil
- Bad fats: -saturated fats -chloesterol too much of them could lead to heart disease.
- Cholesterol is made in the liver and is carried in the blood.
- There are 2 different types of cholesterol: LDL and HDL.
- LDL is a bad cholesterol, as your LDL cholesterol levels rise when some of the fat is deposited on the inside of your arteries.
- HDL is a good cholesterol, because it helps to stop bad cholesterol from building up in your arteries.
- Statins can be used to refuce the amount of lipids, therefrore loweing your cholesterol and blood pressure.
- Elements: carbon, hydrogen, oxygen and nitrogen
- Proteins are polymers made u of many subunits called amino acids. There are 20 different types of amino acids. They can range in order, however the shape and order of them determins the function of the protein.
- Sources of protein: -fish -meats -cheese -eggs
- Souces of protein for a vegetarian: -beans -peas -pulses -cheese -eggs -nuts
- a protein deficiency could lead to a disease called kwashiorkor
- Sources: calcium and iron
- Calcium is used in the body to build strong, dense bones and to keep them healthy.
- If there were to be calcium deficiency in the diet teeth and bones would become soft.
- Deficiency diseases include: rickets and osteoerosis.
- Rich sources: milk and cheese (dairy products)
- Iron is used in the body to transport oxygen from the lungs to tissue and carbon dioxide to the lungs
- If there were to be iron deficiency in the diet you would become very tired.
- A deficiency disease is anaemia.
- Rich sources: red meat, beans and nuts
- Sources include vitamin C and vitamin D
- In the body it helps to transport calcium
- Vitamin D deficiency leads to less bone production and bone tissue may suffer
- Some deficiency dieseases include: osteoperosis in adults, and rickets in children.
- Rich sources: milk and sun exposure
- It is used for growth and repair of tissue
- Vitamin C deficiency leads to paleness, loss of teeth and depression.
- A deficiency disease is scurvy.
- Rich sources: Fruit and vegetables
- Water is needed in every cell in order for it to fuction
- It helps to remove dangerous toxins your body takes in from the air
- It cushions the joints
- Helps to regulate your body temperature
- It keeps your body hydrated
- It helps to transports blood
- Deficiency of water may lead to dehydration, headaches, nausea and in the worst cases death.
- Provides bulk to food to help movement through the digestive system
- Rich sources include: wholegrain, bread, cereals, nuts and dried fruit.
- A healthy diet contains the right balance of the different food types and the right amount of energy.
- It is important to balance the body's demand for energy with the energy gained in respiration from foods (carbohydrates and fats)
- The amount of energy your body requires depends on a number of different factors e.g. amount of physical activity undertaken, metabolic rate
- Fats are much more 'energy dense' that carbohydrates
- Fats have more than twice the energy content per gram (39kJ) compared to carbohydrates (17kJ)
- We get energy from respiration
- All cells respire to generate the energy needed to 'do work'. Some of the energy is heat and helps to maintain our body temperature at 37degreesC
- The process of respiration requires food, mainly carbohydartes e.g. glucose and sometimes fats
Factors affecting Health
- Malnourished- an unbalanced diet
- Too much fats and lack of exerice can lead to obesity
- health problems linked to obesity: heart disease, cancers and type 2 diabetes
- Inherited factors that can affect health: metabloic rates, high cholesterol and high blood pressure
- Metabloism- All the chemical reactionwhich take lace inside a cell
- Chemical reactions can be faster or slower and thius speed is called the metabolic rate
- The metabolic rate varies from person to person
- Someone with a higher metabolic rate will therefore need more energy hence more food will be used in respiration to generate this energy
- Factors affecting the metabolic rate: -muscle needs more energy than fatty tisssue, which means that eole with a higher proportion of muscle to fat in their bodies will have a higher metabloic rate. -Physically large people are likely to have a higher metabolic rate than smaller people; the bigger you are, the more energy your body needs to be suplied with. -Men tend to have a slightly higher rate than women, as they are slightly larger and have a larger proportion of muscle. -Metabolic rate is also affected by the amount of exercie you do. During exercise your metabolic rate increases and stays high for sometime after you finish. Also, regular exercise builds muscle. -Scientists believe that your basic metabolic rate may be affected by genetic factors you inherit from your parents.
- Malnutrition- Literally means "bad eating" and refers to the result of any diet that is seriously unbalanced.
- Energy in = Energy out
- Body mass index (BMI) : This compares your weight to your height.
BMI= mass / (height) ²
- Exercise helps a person to lose weight, beacuse it helps the build u of muscle so their metabolism is high so even more energy is used. Exercise increases the amount of energy used and fat stores will be broken down and used in respiration to generate the extra energy needed.
- Some people are not physically fit, but are slim, this means that they are malnourished.
- Eating too little food can lead to muscle wastage and poor growth in children, fatigue, more suseptible to infection and irregular periods in women.
INFECTION- barriers of infection
- Skin- covers body and acts as a physical barrier preventing the entry of pathogens. I the skin is broken down there are platelets in the blood to help it clot, preventing excessive bleeding and the entry of pathogens.
- Nasal hair and yelinds also act as physical barriers
- Tears contain an acid that kills bacteria.
- Urine contains a mild antiseptic, it also flushes many bacteria out of the urethra
- Saliva contains a chemical which kills bacteria
- There are chemical barriers e.g. stomach acid, mucus in the breathing system and ear wax that also revent pathogens from entering.
Pathogens and disease
- A microorganism is a very small organism which can only be seen using a microscope e.g. bacteria and viruses
- Some microorganisms cause diease, there are known as pathogens.
- Infectious diseases can be caused by a microorganism that can be spread from one person to another. Theses diseases range from the relatively mild ones e.g. colds and tonsilitis through to the killer diseases e.g. influenza and HIV/AIDS
- Pathogens cause disease by either directly damaging your cells or by producing toxins which affect your body. The body responds to this damage with 'symptoms' such as high temperatures, headaches and rashes.
Infectious Disease- A disease which is caused by a microorganism and which can be passed from one person to another
Micro-organism- A very small organism which can only be seen using a microscope
Pathogen- A microorganism that causes disease
Toxin- A poison made by a bacterium or virus
Placebo- An inert sunstance given to the control group. A tablet that does not contain the drug 'sugar pill'
Control group- the group patients/volunteers given the placebo
Blind trial- The patients/volunteers do not know if they have been given an experimental drug or a placebo
Double blind trial- Nether the patients not the doctor know who has given teh experimental drug or the placebo
Bacteria and viruses
- Smaller than animal and plan cells
- No nucleus
- Have a cell wall, cytoplasm and genetic material
- Divide by splitting in two
- Sometimes damage cells
- Often produce toxins
- Cause infectious disease
- Smaller than a dog
- Nno nucleus
- Have a protein coat and genetic materila
- Divide by taking over your cells
- Always damage cells
- Rarely produce toxins
- Cause infectious disease
White blood cells
Despite a variety of physical barriers some pathogens stil manage to get inside the body. Once there, they come into contact with the white blood cells of your immune system.
There are two types of white blood cells:
- The phagocytes engulf/ingest any type of pathogen they encounter. They digest them with enzymes, destroying the pathogen and preventing them from causing disease.
- Thye are multi-lobed nuclei.
- They recognise specific antigens on the surface of a pathogen.
- They produce a unique 'specific' antibody to destroy them.
- they yse memory cells which remain in the blood, they can recognise the same pathogen if it invades again and produce anitbodies quickly.
- Some produce antitoxins which counteract the toxins.
- Have a very large nuclei.
Ways pathogens could be spread in a hospital:
- Doctors and nurses not washing their hands inbetween treating patients
- Dust under beds
- Bedsheets and curatins not being changed on a regular basis
- medical equipment not being cleaned/being left around
How can you stop infection:
- Antiseptic chemicals used on the skin furface destroy microbes. an examles of an antiseptic is carbolic soap
- Disinfectants are chemicals used to clean surfaces where pathogens are found. Some examples of disinfectants includs: -bleach -soap -chlorine
- Patients could be cleaned with antiseptic before any phyiscal contact, and hispital gowns should be worn to ensure that no pathogens are carried outside.
- Patience wounds are cleaned and covered up
- Nurses and doctors washing hands regularly, wearing rubber gloves and sterlise instruments before and after use.
How disease spreads
Droplet Infection: This means coughing and sneezing, because evry time you do these things you expel tiny droplets, full of pathogens, from your breathing system. Other people then breathe in teh dropltes along with pathogens, as a result, picking up the disease. Diseases spread in this way: influenza, tuberculosis or the common cold.
Direct contact: This is when direct ontact of the skin is madde, which may involve shaking hands or bumping into someone. Diseases spread this way are: Impetigo and sexually transmitted infections.
Contaminated Food and drink: This involves eating raw or uncooked food, or drinking contaminated water containing sewage as this can spread disease from the pathogens within contamintaed food or drink. Diseases spread this way: diarrhoea and salmonellosis.
Animals vectors i.e. carriers: This involves a disease being transmitted from an animal. E.g. certain types of mosquito bites send harmful pathogens into the bloodstream, causing Malaria. Other diseases spread this way : rabies and anthrax.
Defence against disease
Immunity- when you have memory cells that remember specific antigens and the correct antibody to produce quickly.
Vaccinations- these can be used at a younf age, they contain dead or very weak amounts of a pathogen, this allows the body to produce antibodies against the disease, but we do not actually suffer from the disease. Once an antibody is made it is remembered and if we were to catch the disease again our memory cells would remember and be able to produce the correct antibodies quickly.
Drugs can be used to trea disease...
- Antibiotics are medicines which can kill disease, causing pathogenic bacteria inside your body to die.
- Examples of antibiotics: ibuprofen, sudafed, paracetamol and aspirin
- Antibiotics can only treat bacteriak based disease.
- To kill viral pathogens it is hard because they reproduce inside your body cells and it is hard to kill the viruses without damaging your own cells and tissues at the same time, therefore viral diseases cannot be treated with anitiotics.
Resistance to antibiotics
In the rigth conditions bacteria grow and divide very quickly (every 20mins) Each new bacterium is usually exactly the same as the one it came from, however sometimes bacterium is prouced slightly different to the others. This is called a mutation, sometimes the mutation causes tehm to be resistant to an antibiotic, therefore more difficult to kill.
Ways in which bacteria could be resistant to antibiotics:
- Deactivating teh antibiotic before it reaches the inside of the bacteria cell.
- Pump the antibiotic out of the cell
- Alter the protein on the bacterial cell so the antibiotic cannot recognise it
- roduce enzymes to destroy the antibiotic
- S.aureas is a harmless bacterium
- S.aureas can be found on the skin or in your nose
- It can become a serious health problem if you become infected, or those who have had an operation or serious burns or people with a low imunity.
- S.aureas has changed into MRSA because some bacterium have mutated and become resistant to methicillin.
- MRSA= Methicillin Resistant Staphylococcus Aureaus
- MRSA is spread by touch
- To prevent MRSA in hospitals hand-washing must be done regularly
- MRSA is described as a superbug because it is resistant to many different antibiotics.
- MMR stands for measels, mumps and rubella
- It is important to be vaccinated again measles and mumps because they can cause serious health problems e.g. brain damage and death
- It is important to be vaccinated against rubella because it can cause damage to unborn babies
- Some reports have suggested that by taking the MMR vaccine it could lead to autism in your child, this meant that some parents stopped their children from having the vaccination
- This method of immunity is called 'arificial' active immunity
- Vaccines work by introducing a small quantity of dead or inactive pathogens into the body, often by injection
- The lymphocytes recognise the antigens on the surface of the pathogen, and strat to produce a 'specific' antibody to destroy the pathogen. This means that the lymhocytes can then remember the 'specific' antibody produced and so if the same pathogen enters the body again it can be killed quickly before you start to fell ill
- Prevents death and permanent side effects from the disease
- All vaccines have been subject to clinical trials and are considered 'safe'
- Vaccines protect against disease which other medicines cannot relieve or treat
- Prevents the spread of infectious disease
- Parents/child may be afraid of needles
- Always risks of side effects to some vaccines
- Vaccination programmes are expensive; some countries unable to afford them
- Some vaccines require boosters to provide full immunity
- some vaccines need to be stored in particular conditions, unable to do so in LEDCs
Pandemica and epidemics
Epidemic- When a disease suddenly spreads rapidly to affect many people
e.g. Influenza spraeding rapidly in Nottingham
Pandemic- When a disease sreads to affect many people quickly over a very large area such as a continent or even the whole world.
e.g. HIV/AIDS in Africa
A drug- A substance that alters the chemical process in your body
- Many drugs are extracted from natural substances
- Drugs are used for medicines and also recreation
- Ilegal- against the law to take or sell, examples: heroin, ecstacy and cannabis
- Legal- Not against the law to take or sell, examples: ibuprofen, nicotine, alcohol
- Prescription- ordered by a doctor for the patient, examples: antibiotics, morphine, anabolic steroids
- Over the counter- can be bought in shops, examles: alcohol, nicotine, ibuprofen
- Recreational- taken for pleasure/to make you feel good/to reduce stress. Some are legal and some are illegal, examples: alcohol, heroin, cocaine
- Performance inhancing- taken my athletes to improve performance. They are banned by sporting authorities. Some are illegal but others can be legally prescribed, examples: anabolic steroids, betablockers
Nerves are not joined up directly to each other. There are junctions between them called synases. The electrical impulse travels along a neurone until the end. Chemicals are released, these diffuse across the gap (synase) in initiate an impulse in the next neurone.
Drugs work by interfering with the movement of chemicals across a synapse.
1. Impulses arrive down axon of first neurone
2. Neurotransmitter diffuses across synapse
3. Neurotransmitter attaches to membrane of second neurone
4. Impulse started in second neurone
5. Neurotransmitter broken down by enzyme from second neurone
- Stimulants- these drugs speed up the activity of the brain, making you feel more alert and energetic. They work by speeding up the rate of chemical transmission at synapses. Examlples: caffeine, nicotine, cocaine, ecstacy
- Sedatives- these drugs slow down the response of your barin and make you feel calm and sleepy. They work by slowing down teh rate of chemical transmission at synapse. examples: tranquilisers, heroin, alcohol, canabis
- Painkillers- these drugs reduce/stop the feeling of pain in the body. They block the chemical transmission at synapse involved in the senation of pain. Examples: morphine, ibuprofen, paracetamol, heroin
- Hallucinogens- These drugs cause you to see or hear things that are not actually there. Thye interfere with the transmissio of chemicals across synapses producing responses to stimuli that have not been received. Examples: Magic mushrooms, cannabis, LSD
How someone becomes addicted- All drugs change chemical processes in our bodie. If drugs are used a lot, our bodies build up a tolerance to them. The 'user' has to use more of the drugs or use them more frequenctly in order to get the same effect. As a drug is used more often or in greater amounts th 'user; becomes more dependent on it.
Addiction- Someone is addicted to a drug when their whole body chemistry changes. they suffer withdrawel symptoms if they stop taking the drug e.g. headaches, pains, aches, shaking and sweating.
Psychological addiction- If a drug becomes central to someone's thoughts and emotions then you can call it a 'crave' for the drug.
- They are divided into two main clases- soft and hard.
- seriously addictive
- e.g. heroin and ecstasy
- quite harmful
- e.g. cannabis
- can be described as 'gateway' drugs, as they 'open the doors' to teh very adictive drugs
CAN ALL CAUSE HEART AND CIRCULATORY SYSTEM PROBLEMS
Illegal drugs in recreation
why use them?
- to improve sporting performance
- to feel good, provide energy, reduce stress
- to socialise and relax with friends
- peer pressure
- To rebel against parents
legal vs. illegal
some legal drugs have more of an impact than illegal drugs.
- smoking causes disease of the heart, blood vessels and lungs
- tobacco smoke causes cancer
- nicotine is the addictive drug found in cigarettes so it is hard to quit
- it is a sedative and affects the nervous system
- slows raetion times and affects co-ordination
- Excessive drinking can cause liver disease and brain damage
- alcohol is addictive
how they imact our society: -cost to the NHS traeting people with heart disease etc. -cost of crime due to drinking -sorrow and anguish to the people affected by them directly or indirectly.
pros for staying illegal:
- if it were to be changed into being legal then a lot more people would take it, this could damage people's health and can endanger people around them
- if it were to be made legal a lot more people would take hard drugs.
- If it were to be made legalised then the authorities would be sending out the wrong message; saying that it is ok to take drugs
cons for staying illegal:
- Medical cannabis can be used to help relieve pain
- some legal drugs are just as dangerous
- police resources can be better spent tackling more serious crimes
Steroids and athletes
Some performance enhancine drugs are illegal and some are prescription only, but all are banned by sporting authorities. Many of theses drugs can have a negative effect on health e.g. steroids
There are also ethical problems with taking performance enhancing drugsL
- athletes have the right to make their won decisions about whether taking drugs is worth the risk or not
- drug free sport isn't really fair anyway- different athletes have acess to different training facilities, coaches, equipment etc.
- It's unfair if people gain an advantage by taking drugs, not just through training
- athletes may not be fully informed of the serious health risk of the drugs they take
steroids in women and men
Problems in men:
- shrinkage of the testicles
- enlarged prostate
- development of breasts
- reduced sperm count
Problems in women:
- reduced breast size
- enlarged ********
- increase in facial and body hair
- deepened voice
- menstrual problems
Problems in both: headaches, moodswings, strokes and blood clots, high blood pressure and heart disease, nausea, bloating, aching joints, aggresive behaviour, increased risk of tendon injuries, urinary and bowel problems, liver damage and severe acne on face and back.
Drugs in sport
Anabolic steroids: they are a drug that taht mimics the effects of testosterone and dihydrotesosterone in the body. Athletes take them to enhance their sporting performane by building up muscle. The risk associated with anabolic steroids for both men and women include liver damage, aggressive behaviour, high blood pressure, blood pressure, heart disease and many more.
Blood doping: EPO stimulates bone marrow and produce more red blood cells and therefore haemoglobin. For this reason EPO is most commonly used amongst endurance athletes as a higher red blood cell count means better oxygen transportation and so a higher rate of aerobic respiration. the faster the rate of aerobic respiration, the higher the level at which the athlete can work without turning to their anaerobic systems which produce lactic acid and cause fatigue.
Diurects: Drugs that are used by athletes to remove excess water from the body, causing dehydration. They are used to make you lose weight rapidly and to dilute teh presence of illegal substances and aid their excretion
Painkillers: realeave pain
Sedatives: They widen the arteries allwong graeter blood flow, they also reduce anxiety.
ADAPTAIONS- animal adaptations
Adaptation- Is a feature that allows an organism to survive in the envirnoment in which it lives in.
e.g. Red kangaroo
lack of food- borad feet to revent damage to shoots. Low metabolism to conserve energy hence will need less food.
lack of water- If tehy eat they do not need water. Store water in the muscles in the gut. At rest they do not sweat to conserve water loss.
Keeping cool- they lick their forearms cooling blood vessels at the surface.
Behaviour- Find shade and memorise pools of water
glucose + oxygen = carbon dioxide + water + energy
- Large: a small surface area to volume ratio hence will lose heat less quickly than smaller animals
- Small ears and tails: reduces the surface area hance will lose heat less quickly
- Thick blubber under the skin: provides insulation hence reduces heat loss throughout their surface. This builds up in the summer months so that they can live off their body fat throughout the winter.
- Thick fur: this traps air and insulates hence reducing heat loss
- Whit fur: provides camouflage so that they cannot be seen easily by their prey
- It conserves energy whne conditions are not favourable for food or temperature
- Allows animals to survive the long winters- lack of food
- When hibernating the animal becomes defensless from predators so a very secure den is needed to protect the.
Some flowers follow the sun to obtain as much heat as possible.
- tehy are usually very small to shelter from the wind
- the wilow tree growas horizontally to shelter from strong winds
Why do plants need water?
carbon dioxide + water =(light energy&chlorophyll)= oxygen + glucose
- water is taken into the cells to ensure the plant is upright and supported
- water evaporates to help plants cool
How do plants lose water?
Water is taken up by specialised root hair cells from the soil. Water moves in an unbroken column in specialised tissue called xylem up the stem of the plant. This is called the transpiration stream. Water evaporates from the leaf cells; this water vaour diffuses out of the leaves via small openings called stomata.
The function of stomata- to allow carbon dioxide into the leaf for photosythesis
- In very hot, bright conditions stomata may close. This prevents photosynthesis, however helps survival in dry conditions.
Some plants are adapted to survive in hot and dry conditions.
e.g. Conifers, gorse and heathers have leaves which are needle like and have a smaller surface area than normal leaves.
Holly and ivy have few stomata and thick waxy covering (cuticle) over the surface of the leaf, reducing water loss even further.
Extremophile- an organism (usually a microorganism) that thrives in physically or geochemically extreme conditions that most life on Eath are unable to survive in. Extremophles have extreme adaptations.
Advantage of being an extremophile: There are fewer organism to compete with for survival
Disadvantage of being an extremophile: They will die if they are taken out of tehir specific environment
Competition- the interaction between organisms triying to obtain the same amout of food or occupy the same space
A good competitor- to be a good competitor an individual has to be very well adapted to the envirnoment in which it lives.
What do animals compete for? Food, mates, shelter (nesting sites/caves/burrows) and social status (alpha males/alpha females)
Territory- an area defended by an animal against other members of the same species to protect its resources i.e. food, shelter, maters.
An example of competition: A male peacock displaying its beautiful long feathers in a courtship behaviour to attract a mate.
Predators- animals which hunt.
Prey- animals which are hunted
competition in plants
what do plants need to survive and why?
water- needed for chemical reactions, such as photosynthesis and to keep plant tissue rigid
Light- needed for photosynthesis
Minerals- needed to make all the nutrients needed to live and grow, such as protein
Calculating percentage difference/yield
(original value- new value) / original value x 100
e.g. (60.5 - 50.8) / 60.5 x 100 = 16.03 percent
Changing envirnoments: organisms have adaptations that help them to survive well in particular conditions so if the conditions change it may make it difficult for them to live in that environment, or it may make it easier for otehr organisms to come into the area and compete. Either way, this may cause a change in the distribution of species.
Effects of climate change (on birds in the uk):
- The arrival of new species, normally found in warmer climates e.g. little egret
- Some species are satying in the uk tehy are not migrating because more food is available i.e. insects- e.g. chiffchaffs
- Some sea bird species are declining in numbers. The rise in sea temperature has affected their food source i.e. sand eels and puffins
Pollutant- a substance that is released into the atmosphere due to human activity that damages the environmet and the organisms that live there.
We pollute the lands:
- Heavy metals from industry
- Pesticides from farming
We pollute the water:
- Fertilisers from farmland
We pollute the air:
- Buring fossil fuels produces sulphur dioxide and nitrogen oxides
- Sulphur dioxide and nitrogen oxides dissolve in rain to produce acid rain (sulphur dioxide and nitric acid)
Cells- structure and function
- The smallest living organisms are single cells. They can carry out all functions of life from feeding and respiration to excretion and reproduction
- Most organisms are bigger and made up of lots of cells i.e. they are multicellular organisms.
Plant cells- organelles and function: plant cells also have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. In addition all plant cells have a cell wall.
- cell wall- made of cellulose which strenghtens the cell and gives it support
- chloroplasts- found in all green parts of the plant. They are green because they contain the substance chlorophyll which gives the plant its colour. They absorb light energy to make food by photosynthesis.
- permanent vacuole- a space in the cytoplasm filled with sap, which is important for keeing the cells rigid to support the plant.
Organells- these are structures found inside cells. Organelles differ in their structure and hence have very different functions
Animal cells- organelles and function: all animal cells have the following organelles:
- nucleus- controls all the activities of the cell. It alos contains instructions for making new cells or organisms.
- Cutoplasm- a liquid gel in which most of the chemical reactions needed for life take place e.g. respiration
- Cell membrane- controls the passage of substances in and out of the cell
- Mitochondria- structures in the cytoplasm where most of the energy is released during respiration.
- Ribosomes- where protein sythesis takes place. All the protein needed in the cell are here.
Cells may be specialised to carry out a particular function.
Many specialised cels have different shapes and many have specific features that are related to what they do i.e. their function
Sometimes cells become so specialised that they only have one function within the body e.g. sperm, ovum and red blood cells,
red blood cells
Function: To carry oxygen around the body
- Bioconcave shape provides a large surface area to pick up/ release oxygen efficiently.
- The cells are small and flexible, tehy can squeeze through narrow capillaries
- They have no nucleus, this allows more room for oxygen
- They contain a red pignet- heamoglobin, this attracts oxygen
Circulatory- to carry oxygen and food around the body. e.g heart, blood vessels, blood.
Digestice system- to digest and absorb food. e.g. gut, pancreas and liver
Nervous system- to detect stimuli and conduct electrical messages from one part of the body to another. e.g. brain, spinal cord, sense organs
Musculoskeletal system- to support, protect and move the body. e.g. muscles, ligamnets, skeleton
Excretory system- to get rid of poisonous waste substances. e.g. kidneys, bladder, liver.
Respiratory system- to take in oxygen and get rid of carbon dioxide. e.g. trachea, bronchi, alveoli