Biology

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Cells

Nucleus - Controls activities of cell

Mitochondria - It is where energy is released

Ribosomes - Where protein is made

Chloroplasts - Absorp light from chlorophll

Cytoplasm - Where chemical reaction happen

Cell membrane- Holds cell together and controls what goes in and out of cell

Cell wall- Made of cellulose, Strengthens cell

Dna called plasmaids (Bacterial)

Strands of DNA which floats in cytoplasm (Bacterial)

Prokaryatic------> Small and simple, bacterial cell

Eukaryatic-------> Complex and larger, plant and animal cell

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Microscopy

-Allow us to magnify image in greater detail

Light microscopes

- Have a limited magnification, magnification not powerful

- Limited resolution, image is blurred

- Use light and lenses to form image

Electron microscopes

- Greater magnification and resolution than light microscopes

-Uses electrons to from image

                           Size of image                                                                                                           Magnification =  Real object size

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Specialised cells

-Do a specific job  - When cells become specialised,scientists call it differentiation

Sperm cells contain half genetic information.Get male DNA to female DNA. Long tail and streamlined head to help get to egg and mitochonria used for energy.Carries enzymes in head to digest through egg.

Nerve cells send electrical signals around body. Long and have branched connections at ends to connect to other nerve cells and form network around body.

Muscle cells contract quickly.Mitochondria to genrate energy needed for contraction.

Root hair cells on surface of plant roots which grow into long hairs that stick out into soil. Gives plant large surface area for absorbing water and mineral ions from soil.

Phloem and xylem cells from tubes which transport substances such as food and water around plants. Xylem cells hollow and phloem have few subcelluar structures so stuff can flow through them.

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Stem cells

It is an undifferentiated cell which can differentiate into different types of cells. Found in human embroyos

Adults have stem cells like bone marrow and can only turn into certain cells like blood cells. They also cure diseases.

E.g A healthy person's bone marrow can be given to a patient's faulty blood cells, Therapeutic cloning is embryo made with same genetic information so patient won't reject cell.

Risks are viruses which can be passed to patient. Some people are against this because it takes a potential life.

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Mitosis

- Human body cells contain 23 pairs of chromosomes

- Chromosomes carry large number of genes

DNA is spread into long strings. It duplicates and increases mitochondria and ribosomes. the DNA is pulled apart from each other and two nucleus form. Then the membrane splits into 2 daughter cells.

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Diffusion

Diffusion is spreading out of particles resulting in a net movement from an area of higher concentration to an area of lower concentration.

What effects diffusion?

Concentration gradient ( Difference in concentration). The greater concentration gradient the faster diffusion takes place.

The higher the temperature, the greater rate of diffusion because more particles can diffuse

When distance is small, faster diffusion

When no difference in concentration gradient, slower diffusion.

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Osmosis

It is movement of water molecules across partcially permeable membrane from a regien of higher water concentration to a regien of lower water concentration.

Partically permeable membrane allows small molecules to pass not big molecules.

During osmosis cells become flaccid when water moves out of cell. It loses shape and becomes smaller.

During osmosis cells become Turgid, when water moves into cell. It is bigger.

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Active transport

Particles move against concentration gradient

Transports particles into a regein of lower concentration to a regein of higher concentration. Has partially permeabe membrane. Uses energy to take from low to high. Energy from resperation.

Example:

Root hair cells transport magnesium into plant from soil. Concentration of magnesium in soil is lower than concentration inside root hair cell so active transport is used to move magnesium into cell. These magnesium ( ions ) are then transported into system vessels and moved to leaf. Root cells have lots of mitochondria and provide energy for active transport.

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Communicable diseases

Spreads from person to person and are infectious. Spread by pathogens which are microorganisms that cause infectious disease. Diseases from pathogens: - Bacteria - Viruses -Protists -Fungi

Bacteria 

Small living cells which reproduce rapidly inside body. Release harmful chemiclas called toxins that damage cell and make you fell ill.

Viruses

Only replicate using cells. When virus leaves it causes cell to burst open.Cell damage is what makes you fell ill.

How do pathogens spread?                                    Reducing spread of disease.

-Air e.g water droplets (influenza)                          -Hygenic e.g washing hands

- Water,drinking dirty water e.g Chlora                  -Isolate infected person E.g Ebola

-Direct contact E.g HIV                                         - Vaccination

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Viral disease

Cannot be killed by antibiotics. 

Measles 

High temperature,red skin rash,spread in droplet's when infected person sneezes/coughs. Complications to brain and breathing system. Most people vaccinated when young.

HIV

Spread by sexual contact/exchanging bodily fluids. Flu like symptons for few weeks.Controlled by antiretraviral drugs which stops virus replicating.

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Bacterial disease

Can be killed using antibiotics

Salmonella (Food poisining)

Caused by injesting infected food. Food prepared in unhygenic conditions. Symptons caused by toxins that bacteria produce. Symptons are fever,vomiting,cramps,diarrhea. Salmonella found in chicken. In UK all chicken vaccinated to prevent disease.

Gonorrhoea (Sexually transmitted disease) 

Symptons are thick yellow/green discharge, pain when urinating. In the past easily traeted using antibiotic penicillin. Now antibiotic resistant strains of bacteria are common. Stop it by using condom.

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Protists disease

Protist

Many types, bit all eukaryatic and single celled. Some are parasites. Parasites live in or inside other organisms and can cause damage. Transferred by insects.

Protist disease

Malaria

Malarial protist life cycle takes palce inside mosquitos. Mosquitos are vectors that pick up malarial protist when feeding on infected animal. Every time mosquito feeds another animal it infects it and injects protist into animal's blood vessels.

To stop spread of malaria, mosquitos can be stopped from breathing. Also mosquito nets and using injectcides.

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Fungi

-Single celled. Body made up from hyphae (thread like structure).

- Grow and penetrate om human skin and surface of plant causing diseases.

Produce spores which are spread to other plants and animals

Fungal disease

Rose black spot is a fungus that causes purple or black spots to form on leaves of rose plants. Leaves turn yellow and drop-off. This means less photosynthessis so plant dosen't grow well.

Gardeners treat diseases using fungicides and ********* part of plant that is affected. Leaves need to be destroyed so fungus dosen't spread

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White blood cells

Protect us from pathagons

1) White blood cells ingest pathogens (Microorganisms) and destroy them (Phagocytosis).

2) White blood cells produce antibodies which destroy particular bacteria or virus. Antibodies lock on pathogens and destroy them. Antibodies against one pathogen cannot protect you from another pathogen.

3) White blood cells produce antitoxins which neutralise toxins released by pathogen. Toxins are harmful and change temperature + PH. Antitoxins and toxins join.

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Vaccination

Protects us from future infections by that specific  pathogen

MMR vaccine protects us from measles,bumps and rubella.

When a person is vaccinated they are given a dead or inactive from of pathogen. Inactive pathogen so won't develop disease. White blood cells produce antibodies against dead pathogen. White blood cells reproduce. Years later if attcked by pathogen you can produce antibodies more rapidly fighting pathogen off.

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How can drugs be used to treat diseases?

Painkillers are drugs that releive pain. They block nerve impulses so no pain felt. Don;t cure diseases or kill pathogens E.g Paracetomal, Ibrofen, Ointment

Antibodies kill becateria. Don't kill body cells. They don't destroy viruses which reproduce using body cells because if you killed the virus, you would also kill the body cell. Antibiotics has reduced deaths. E.g penicillin

Bacteria can become resistant to antibodies

Bacteria can mutate (change). Causes them to be resistant, to not be killed by an antibiotic.

If you have an infection some bacteria might be resistant to antibiotic which means when you treat infection bacteria will survive and reproduce

Resistant strain can cause serious infection that cannot be treated by antibiotics. To slow down resistant strains docters should not over prescribe antibiotics.

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Lungs

Lungs in the thorax ( Top part of body)

They are protected by ribcage and surrounded ny pleural membrane.

Air you breathe in goes through treachea which are split into 2 tubes called bronchi, then split smaller into bronchioles.

Bronchioles end at small bags called alveoli where gas exchange happens,

Alveoli surrounded by network of blood capillaries.

Blood passing next to alveoli returns from lungs to rest of body so contains lots of CO and little oxygen.Oxygen diffuses out of alveolous (high concentaron) into the blood.Carbon dioxide diffuses out of blood (high concentration) into alveolus (low concentration) to be breathed out.

When blood reaches body cells oxygen is released from red blood cells (high concentarion) and diffuses into body cells (low concentration). At same time carbon dioxide diffuses out of body cells into blood.

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Photosynthesis

Carbon dioxide + water --------> oxygen + water

6CO  + 6H O  --------> C H O + 6O

During photosynthesis level of carbon dioxide is low inside the leaf.

Creates big concentration gradient, so carbon dioxide diffuses into cell.

Oxygen and water vapour diffuse out through the stomata.

Size of stomata controlled by guard cells which close stomata if losing water faster than replacing the roots.

During photosynthesis level of oxygen is high inside the leaf.

CO diffuses into air spaces within the leaf, then diffuses into cells where photosynthesis happens

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How is the small intestine adapted?

The villi increases overall surface area of the small intestine, increasing volume of substances which can be absorped by diffusion.

It has a blood supply to absorb nutrients.

The villi is inside small intestine.

They increase surface area so digested food is absorbed more quikcly into the blood.

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Enzyme structure

A catalyst speeds up reaction but isn't used up. Lowers activation energy.

Enzymes

Large proteins and all proteins made from amino acids.

Enzymes have active site with special shape to allow other molecules to fit into enzyme. For enzyme to work substrate has to fit so it can be catalysed.

When enzymes are affected by temperature and PH it affects active site of enzyme. It becomes denatured and stops working. For example if temp is too high some of bonds holding enzymes together break which changes size of enzymes active site so substrate won't fit.

Enzyme     Where it is made?                             What it does?                                                           Amylase    Salivary glands,small intestine      Breaks down large starch molecules

Protese     Stomach, Small intestine              Breaks proteins into amino acids

Lipases     Pancraese, Small intestine            Breaks lipids (fats) into fatty acids and glycerol

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Digestive system

Salivery glands - Found in mouth. Makes saliva. Saliva makes it easy to swallow food. Contains amylase which breaks down starch to sugar.

Oesophagus is connected to stomach. Moves food quickly to stomach.

Stomach is a small organ. Releases proteze which is breakdown of protein. Stomach releases acid which has PH of 2-3. Acid destroys pathogens with food or water.

Liver is a large organ. Produces green liquid called bile which helps breakdown fats. Bile not enzyme and made in liver but stored in gall bladder before releaseing into small intestine. Bile neutralises stomach acid.

Pancreas produces proteaze,amylase and lipase enzymes. Releases them into small intestine.

Small intestine is where digested food is absorbed out of digestive system into blood.

Large intestine where excess water is absorbed from food.

Rectum where faeces (indigestable food) are stored before coming out of anus.

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The circultary system

Double circultary in mamals (humans) :

-1 transport system carries blood from your heart to your lungs.                                                    - The other transport system carries blood from your heart to other organs of your body and back.

The heart

1) Deoxygenated blood from body travels through vena cave into heart and passes into right side atrium                                                                                                                                                 2) The right side atrium contracts forcing blood through a valve into right ventricle.                        3) The right side ventricle contracts and forces blood up pulmonary artery to lungs where blood is oxgenated.                                                                                                                                          4) The oxygenated blood enters heart through pulmonary vein into left atrium.                                5) The left side atrium contracts forcing blood through a valve into left ventricle                                6) Left side ventricle contracts and forces blood up the aorta which carries blood to brain and body.                                                                                                    

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Blood vessels

Arteries carry blood away from the heart. (Always oxygenated apart from  pulmonary artery). Thick muscular walls so can withheld pressure. Control flow of blood. Small passageways fro blood. Contain blood in high pressure because high pressure only goes in 1 direction.

Capillaries link arterioles to veins.Big but small compared to veins and arteries. Really thin. Atreries become capilaries by becoming smaller. Gas exchange will occur and will turn into vein. Found in muscles and lungs. One cell thick. Very low blood pressure. No valves,muscle,elastic.Thin layer of cells.

Veins carry blood towards the heart.(Always deoxygenated apart from  pulmonary artery). Have thin walls and larger internal lumen. Contain blood under low pressure. Hve valves to prevent blood flowing backwards.

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Coronary heart disease (CHD)

Disease of arteries. Supplying the heart.

Main cause of CHD is atherosclerosis; a thickening of arteries caused by build up of fatty plaques on the inside walls, Atherosclerosis can lead to reduced blood supply to tissues with fatal consquences.

Cholestrol - Good and bad

Bloodstream transports cholestrol around body attached to proteins. The condensation of cholestrol and proteins is called lipo protein.

2 types of lipo protein

-Low density-LDLs- carry cholestrol from liver to cells-Bad-Builds up cholestrol

-High density-HDLs-Carry excess cholestrol back to liver-Good-Stops build up of cholostrol

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Stages of CHD

Stage 1                                                                                                                                        Blood flows through arteries under pressure which contains cholestrol.

Stage 2

Cholestrol which ic carried by LDL sticks to wall of artery forming a plaque.

Stage 3

Space in artery decreases so blood pressure increases, Makes blood vessel burst damaging body systems

Stage 4

The narrowed artery can easily be blocked when blood clot gets stuck on plaque. Plaque comes away from artery wall and causes blockage.

Stage 5 - If arteries leading to heart become blocked, the heart is starved of oxygen and stops working. This is an heart attck.

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Artificial treatments for CHD

Artificial hearts                                                                                                                                     - If someone needs a heart transplant they need to wait for a donar.                                                 - Scientists have developed temporary hearts that can support natural heart until replaced.             - A machine only lasts a couple of years

Stents                                                                                                                                     Coranary arteries can become narrow as we age or with fatty deposits. Docters solve it by using stents. A tiny balloon is inflated to open the blood vessels which allow blood to flow.

Leaky valves                                                                                                                                Heart valves keep blood flowing in the right direction.They can weaken and leak. This causes someone to be breathless and die. Docters replace valves.

Statins are group of drugs that lower amount of cholertrol in your blood.

Mechanical                                                       Biological                                                                    Lasts long time,                                                Taken from pigs, Lasts 15 years

Take medicines for life to stop blood clots        No medication required

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Non-Communicable diseases

Don't spread from 1 person to another

CHD

Blood vessels called coronary arteries supply blood to the heart muscles. If they become blocked, heart attack can happen.

Risk of haveing heart disease increased by:

- Smoking    - High blood pressure  - High levels of salt in diet  - High level of satured fat in diet

Diabities is a condition where blood sugar level is higher than normal

Type 1 - Inulin dependant. Seen in young people. Inject insulin

Type 2- Non-insulin dependant. Seen in older people. Tablets

The trends show change in diet. As the years have gone on there is a high increase of diabetes because more fast foos, shops,transport and less excersise.

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Non-Communicable diseases

Diet,smoking and lack of exercise, Cardiovascular disease,  Narrows arteries, build up of chlostrol that block arteried                                                                                                              Obesity and lack of excersise, Type 2 diabetes,  Body cells do not respond tot he hormone insulin which helps control blood glucose levels                                                                             

Alcohol, Liver disease,  Long term alcohol causes liver cirrhosis. Stops liver from removing toxins,stroing glycogen and bile                                                                                                Alcohol, Brain function, Deprescent which slows things down. Slows nervous system and relaxes brain, Alcohol reaches brain in 1 minute and too much alcohol damages brain.                 Smoking, Lung disease and cancer, Smoking can cause cancer of lungs,nose,mouth,throat,liver and blood.Increases asthma.                                                                                                  Smoking and alcohol, underdevelopment of unborn babies, Chemicals pass through lacenta to unborn babies. Baby does not have develped liver which leads to miscarriage/premature Carcinogens and ionising radiation, Cancer, chemical and radiation cause cancer                                                                                                         

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Cancer

When abnormal cells divide in a uncontrollable way.

Tumour - Lump caused by uncontrolled growth of cells

Benign - Tumour grows until there is no more room. Tumour stays in one place rather than invading other tissues in body. Not dangerous and tumour is not cancerous.

Malignant - Tumour grows and spreads to healthy tissues. Cells can break off and spread to other partd of body  by travelling in blood stream. Dangerous and cancerous.

Risk facters

Smoking

Obesity

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Plant cell organisation

Lots of cells make tissues, lots of tissues make organ, and lots of organs make organ system.Plant organ:shoots, Stems- Supports leaves+flowers of plant,roots- Needed for absorption of water and mineral ions from soil,leaves- Site of photosynethese in plant.

Tissues -

Epidermal tissue covers whole plant.

Pallisade mesophyll tissue is part of leaf where most photosynthese happens.

Spongy mesophyll tissue is in the leaf and contains big air spaces to allow gases to diffuse in and out of cells. 

Xylem and phloem transport water,mineral ions and food around the plant

Meristem tissue found at  growing tips of shoots and roots and is able to differentiate into lots of different types of plant cell allowing plant to grow.                   

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Cross section of a leaf

Tissues - Epidermal tissues are  covered with waxy cuticle which helps reduce water loss by evaperation.

The upper epidermis is transparent so light can pass through to the palisade layer.Pallisade mesophyll tissue is part of leaf where most photosynthese happens. The palisade layer has lots of chloroplasts so on top of leaf where they get most light.

 Xylem and phloem form a network of vascualr bundles which deliver water and other nutrients to entire leaf and take away glucose produced by photosynthesis and also support structure.

Tissues of leaves are adapted for efficient gas exchange E.g The lower epidermis is full of little holes called stomata which let CO diffuse directly into the leaf. Opening and closing of stomata controlled by guard cells. Air spaces in Spongy mesophyll tissue increase reate of diffusuion of gases.            

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Evaporation and transpiration

The stomata is opened when carbon dioxide goes into leafs and oxygen and water vapour leaves it.

When stomata is open, plants lose water vapour. Water vapour evaporates from cells leaving air spaces and then passes out of leaf through stomata by diffusion.

Transpiration is when water evaporates from stomata.

An adaption of root hair cells is large surface area so can absorb water.

Water is pulled up through plant by evaporation of water from surface area

Water needed for plant so photosynthesis and to keep plants turgid

Environmental factors that affect rate of transpiration is light intensity,temperature,wind,humidity.

Water is lost from leaf by evaporation. Done by open stomata.

In stem water moves up and into leaves to replace water loss by evaporation.

Water moves into roots from soil by osmosis. This replaces water moving up the stem.

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Factors affecting rate of transpiration

Light intensity- Increased light intensity, increases rate of photosynthesis. Stomata will be open to increase rate of carbon dioxide

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Translocation

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