organisation

Cells - basic building blocks that make up living organisms

Specialised cells - cells that carry out a particular function, organised to form tissues

Diffrentiation - process by which cells become specialised, occurs during the development of a multicellular organism

Multicellular organisms - have different systems inside them for exchanging and transporting materials

• tissues include more than one type of cell

Tissue - a group of similar cells that work together to carry out a particular function

Muscular tissue - contracts to move whatever it's attached to

Glandular tissue - makes and secretes substances like enzymes and hormones 

Epithelial tissue - covers some parts of the body (inside of the gut)

• organs are made up of different tissues

Organ - a group of different tissues that work together to perform a certain function

Stomach

• muscular tissue - helps churn up food
• glandular tissue - makes digestive juices to digest food
• epithelial tissue - covers outside and inside of stomach

• organ systems work together to make entire organisms

Organ system - a group of organs working together to perform a specific function

Digestive system

• glands (pancreas and salivary) - produce digestive juices
• stomach - where food is digested
• liver - produces bile
• small intestine - food is digested and soluble food molecules are absorbed
• large intestine - water is absorbed from undigested food, leaving faeces

• help get oxygen from the air into the bloodstream so it can get to your cells for respiration
• helps get rid of carbon dioxide in the blood
• exchange of gases happens in the lungs
• air is forced in and out of the lungs by breathing

• lungs are in the thorax
• the thorax is the top part of the body
• separated from the lower part of the body by the diaphragm
• lungs are like pink sponges which are protected by the ribcage
• surrounded by pleural membranes

• breathe in air through the trachea
• the trachea splits into two tubes (bronchi)
• bronchi split into smaller tubes (bronchioles)
• end of bronchioles are alveoli

• air sacs
• surrounded by a network of capillaries
• where gaseous exchange takes place

• blood passing by alveoli contains lots of carbon dioxide
• oxygen diffuses out of alveoli into the blood
• carbon dioxide diffuses out of the blood into alveoli to be breathed out

• blood reaches body cells
• oxygen released from red blood cells and diffuses into body cells
• carbon dioxide diffuses out of body cells into the blood then carried back to lungs

• breaths per minute = number of breaths ÷ number of minutes

112 ÷ 8 = 14                                           14 breaths per minute

• number of minutes = number of breaths ÷ breaths per minute

112 ÷ 14 = 8                                                                8 minutes

• number of breaths = breaths per minute × number of minutes

14 × 8 = 112                                                             112 breaths

• to get food and oxygen to every cell in the body
• carries waste products (carbon dioxide, urea) to be removed from the body

• circulatory system includes heart, blood vessels and blood

1st circuit

• right ventricle pumps deoxygenated blood to lungs to take in oxygen 
• blood then returns to heart

2nd Circuit

• left ventricle pumps oxygenated blood around body
• blood gives up oxygen at body cells 
• deoxygenated blood returns to heart to be pumped to lungs

• walls of heart made of muscle tissue
• the heart has 4 chambers (right atrium and ventricle, left atrium and ventricle)
• 4 main blood vessels (vena cava, pulmonary artery, and vein, aorta)
• valves - prevent backflow of blood
• coronary arteries - branch off the aorta, makes sure heart gets all the oxygenated blood

• blood flows into 2 atriums from the vena cava and pulmonary vein
• atria contract, pushing blood into ventricles
• ventricles contract, forcing blood into the pulmonary artery and aorta and out of the heart
• blood flows to organs through arteries and returns through veins
• atria fill again 
• repeats cycle

• resting heart rate controlled by a group of cells in the right atrium wall
• cells produce small electric impulses which spread to surrounding muscle cells causing them to contract

• artificial pacemaker used if natural cells don't work properly
• a device implanted under the skin and has a wire going to the heart
• produces an electric current to keep heart beating

Arteries - blood vessels that carry blood away from the heart towards the organs

Structure

• artery walls are strong and elastic - blood is at high pressure
• thick layers of muscle - allow them to stretch and spring
• thick walls and lumen

Capillaries - carry blood close to every cell in body to exchange substances with them

Functions

• supply food and oxygen to cells
• take away waste products (carbon dioxide)

Structure

• really small
• permeable walls - allow substances to diffuse in and out, increases the rate of diffusion
• narrow - gives large surface area, increases the rate of diffusion
• no lumen

Veins - carry blood to the heart

Structure

• thin walls - blood is at low pressure
• larger lumen - help blood flow
• valves - keep blood flowing in the right direction 

• rate of blood flow = volume of blood ÷ number of minutes

1464 ÷ 4.5 = 325                                                       325 ml/min

• volume of blood = rate of blood flow × number of minutes

325 × 4.5 = 1464                                                            1464 ml

• number of minutes = volume of blood ÷ rate of blood flow

1464 ÷ 325 = 4.5                                                           4.5 mins

Blood -  is a tissue

Function

• transport substances around the body

Structure

• made up of red and white blood cells, platelets which are all in a liquid called plasma

Function

• transport oxygen around the body

Structure

• biconcave shape - gives a large surface for absorbing haemoglobin which carries oxygen
• no nucleus - allows more room for haemoglobin which carries oxygen

• in lungs, oxygen diffuses into the blood
• oxygen combines with haemoglobin to become oxyhaemoglobin

• in body tissue, oxyhaemoglobin splits into haemoglobin and oxygen 
• releases oxygen into the cells

Functions

• defend against microorganisms that cause disease
• engulf unwanted microorganisms and digest them
• produce antibodies to fight microorganisms
• produce antitoxins to neutralise toxins produced by microorganisms

Structure

• have a nucleus unlike red blood cells

Platelets - small fragments of cells

Structure

• no nucleus

Functions

• help the blood to clot to prevent excess loss of blood
• stops microorganisms from getting in at the wound
• lack of platelets can cause excessive bleeding and bruising

Plasma - a pale straw-coloured liquid that carries just about everything in blood

Function

• carries red and white blood cells and platelets
• carries nutrients that get absorbed from the small intestine and taken to cells
• carries carbon dioxide from organs to lungs
• carries urea from the liver to kidneys
• carries hormones and proteins
• carries antibodies and antitoxins produced by white blood cells

• made of organs (stems, roots, and leaves)
• epidermal tissue - covers the whole plant
• palisade mesophyll tissue - part of the leaf where photosynthesis happens
• spongy mesophyll tissue - contains big air spaces to allow gases to diffuse in and out of the cell
• xylem and phloem - transport water, minerals, and food around the plant
• meristem tissue - able to differentiate into different types of plant cell allowing plant to grow

Epidermal tissue

• covered with a waxy cuticle
• helps reduce water loss by evaporation

Upper epidermis

• transparent so light passes through to palisade layer

Palisade layer

• lots of chloroplasts
• near the top of the leaf to get the most light

Xylem and phloem

• deliver water and other nutrients to the entire leaf
• take away glucose produced by photosynthesis
• help support the structure

Lower epidermis

• full of little holes (stomata)
• let carbon dioxide diffuse directly into the leaf

Spongy mesophyll

• air spaces 
• increase rate of diffusion

Structure

• made of columns of elongated living cells
• has small pores in end walls to allow cell sap to flow 

Cell sap - liquid made up of the substances being transported and water

Functions

• transport food substances made in leaves to rest of plant
• translocation
• goes from leaves to roots
• or goes from roots to leaves

Structure

• made of dead cells joined end to end
• no end walls between them
• have a hole down the middle
• strengthened with lignin

Functions

• carry water and mineral ions from roots to stem and leaves

Transpiration - movement of water from roots through xylem and out leaves

Transpiration - loss of water from a plant

Transpiration stream - the movement of water through a plant from roots to leaves

Transpiration stream

• water from inside the leaf evaporates
• then diffuses out of the leaf through stomata on the underside of the leaf
• creates a shortage of water in the leaf
• water is drawn up from the rest of the plant through xylem vessels
• more water is drawn up from roots
• constant transpiration stream of water through the plant

Stomata

• gases can be exchanged easily
• more water inside the plant than in the air outside
• water escapes leaf through stomata by diffusion

Light intensity

• brighter the light, greater transpiration rate
• stomata close when it's dark, photosynthesis can't happen

Temperature

• warmer it is, faster transpiration happens
• water particles have more energy to evaporate to diffuse 

Airflow

• better airflow, greater transpiration rate
• poor airflow, water vapor stays by leaf, slower diffusion
• good airflow, water vapor leaves, quicker diffusion

Humidity

• drier the air, faster transpiration happens

• measure uptake of water by a plant

Potometer

• set up apparatus
• record starting position of air bubble
• start stopwatch
• record distance moved by bubble per unit of time
• keep conditions constant through the experiment

• rate of transpiration = distance moved ÷ time taken

66 ÷ 60 = 1.1                                                        1.1 mm/min

• distance moved = time taken × rate of transpiration

60 × 1.1 = 66                                                                66 mm

• time taken = distance moved ÷ rate of transpiration

66 ÷ 1.1 = 60                                                              60 mins

Guard cells - open and closes the stomata in a leaf

• two guard cells surround each stoma

Function

• the plant has lots of water, guard cells fill, go turgid, stomata open, gases can be exchanged
• plant short of water, guard cells lose water, go flaccid, stomata close, stops water vapor escaping

Thin outer and inner walls

• make opening and closing work

More stomata on the underside of the leaf

• close at night to save water without losing photosynthesis
• sensitive to light

• number of stomata = (area of field of vision ÷ total area of surface) × average number of stomata per field of vision

The average number of stomata per field of vision 

• count stomata on different fields of vision
• repeat this 3 times
• work out the average

Health - state of physical and mental wellbeing

Diseases - responsible for causing ill health

Communicable diseases - spread from person to person or between animals and people (contagious or infectious)

• causes are bacteria, viruses, parasites, and fungi
• for example - measles and malaria

Non-communicable diseases - can't spread between people or between animals and people

• last a long time and get worse slowly
• for example - asthma, cancer, and coronary heart disease

Immune system

• increased chance of suffering from communicable diseases
• body less likely to defend itself against pathogens
• for example - catching the flu

Liver

• hepatitis virus causes long term infections
• more likely to develop liver cancer

Diet

• a balanced diet provides the body with everything it needs
• poor diet affects physical and mental health

Stress

• being under lots of stress leads to health issues

Life situation

• easy access to medicines to treat illnesses
• vaccines to prevent getting ill in the first place

Coronary heart disease

• coronary arteries get blocked by fatty materials
• causes arteries to become narrow 
• blood flow is restricted to the heart
• lack of oxygen to the heart muscle
• result in a heart attack

Stents - wire mesh tubes that inserted inside arteries to widen them and keep them open

Functions

• keep coronary arteries open
• make sure blood passes to heart muscles
• keeps person's heart beating

Advantages

• lowers the risk of heart attack
• effective for a long time
• quick recovery time

Disadvantages

• risk of complications and infection
• risk of developing blood clot near the stent (thrombosis)

Statins - drugs that reduce the amount of 'bad' cholesterol in the bloodstream

Cholestrol - a lipid that your body produces and needs to function properly, however too much can cause health problems

Advantages

• reduce risk of strokes, coronary heart disease, and heart attacks
• reduce the amount of 'bad' cholesterol
• increase amount of 'good' cholesterol

Disadvantages

• someone could forget to take them
• negative side effects (headaches, memory loss, kidney/liver failure)
• effect of statins isn't instant

Artificial hearts - mechanical devices that pump the blood for a person whose heart has failed

Advantages

• less likely to be rejected by the body

Disadvantages

• surgery can lead to bleeding and infection
• increase in the chance of blood clots and strokes
• may be uncomfortable for patient

Biological valves - valves taken from humans or mammals

Mechanical valves - man-made

• replacing valves is less drastic than an artificial heart
• still problems with blood clots

Artificial blood - a blood substitute to replace lost volume of blood

• replace the function of lost red blood cells
• no need for a blood transfusion

Risk factors - things that are linked to an increase in the chance for a person to develop a disease

Examples

• exercise
• air pollution
• substances already in the body

Smoking

• damages wall of arteries and cells in lungs

Obesity

• struggles to control the concentration of glucose in the blood

Alcohol

• damages intestines, brain function, and nerve cells

Smoking

• reduces the amount of oxygen

Cancer

• damages cell's DNA 

• non-communicable diseases
• tens of millions of people around the world die per year
• people with these diseases may have a lower quality of life or a shorter lifespan
• affects themselves and loved ones

• non-communicable diseases
• cost to NHS for researching and treating the diseases
• families may have to adapt their home to help ill family member
• an ill family member will have to stop working so reduced family income
• reduction in the number of people able to work also affects the country's economy

Cancer - caused by uncontrolled cell growth and division

Benign tumours - tumour grows until there is no more room

• tumour stays in one place
• not normally dangerous
• isn't cancerous

Malignant tumours - tumour grows and spreads to neighbouring healthy tissues

• invade healthy tissues elsewhere
• form secondary tumours
• are dangerous
• can be fatal
• are cancerous

• anyone can develop cancer
• risk factors increase the chance of developing cancer
• associated with aspects of person lifestyle
• associated with genetics

Smoking

• linked to lung cancer

Obesity

• linked to bowel, liver, and kidney cancer

UV Exposure

• exposed to UV rays by the sun, the higher chance of skin cancer

Infection

• viruses were shown to increase chances of developing cancers

Genes - control activities of cells and characteristics

• inherit genes from parents
• can inherit faulty genes
• make you more susceptible to cancer

For example - mutations in the BRCA genes have been linked to an increased chance of getting breast and ovarian cancer

Catalyst - a substance that increases the speed of reaction without being changed or used up in reaction

Enzymes - large proteins that act as biological catalysts

Proteins - made of chains of amino acids

• living things produce enzymes that act as biological catalysts
• enzymes reduce the need for high temperatures
• have enzymes to speed up chemical reactions in the body

Substrate - a substance that an enzyme acts on

• each enzyme has an active site
• enzymes only catalyse one specific reaction
• for an enzyme to work, the substrate has to fit in active site
• if substrate doesn't fit, the reaction won't be catalysed
• 'lock and key' method

'Induced fit' model

• active site changes shape a little as substrate binds
• to get a tighter fit

Optimum conditions - enzymes need the right conditions to work 

Temperature

• higher temperature, increases the rate of reaction
• too hot, bonds holding enzymes together break
• too hot, changes the shape of the active site so substrate doesn't fit
• results in enzyme being denatured
• enzymes normally work best at 37⁰C 

pH

• too high or too low, breaks bonds holding enzymes
• too high or too low, changes shape of active site so substrate doesn't fit
• results in enzyme being denatured
• most enzymes work best around pH 7 but can change

• rate = 1000 ÷ time

1000 ÷ 90 = 11s‾¹

• rate = change ÷ time

24cm³ ÷ 50s = 0.48cm³/s

Digestive system - nutrients get absorbed in body from gut

Mechanical digestion - teeth grind food, stomach churns it

Chemical digestion - enzymes help to break down the food

1. mouth/salivary glands

2. liver

3. gall bladder

4. stomach

5. pancreas

6. small intestine

7. large intestine

• work outside body cells
• produced by cells in the gut lining
• released into the gut to mix with food molecules

• enzymes break down big, insoluble molecules into smaller, soluble ones
• small molecules pass easily through walls 
• used to make new carbs, proteins, and lipids

• convert carbohydrates into simple sugars
• an example is an amylase
• breaks down starch

Amylase

• made in salivary glands, pancreas, and small intestine
• works in the mouth and small intestine

• catalyse the conversion of proteins into amino acids
• made in stomach, pancreas, and small intestine
• work in the stomach and small intestine

• catalyse the conversion of lipids into glycerol and fatty acids
• made in the pancreas and small intestine
• work in the small intestine

• produced in liver
• stored in the gall bladder
• released into the small intestine

• bile is alkaline
• neutralises acid and makes conditions alkaline
• digestive enzymes work best in alkaline conditions

• emulsifies fat
• breaks down fat into tiny droplets
• gives a bigger surface area for lipase to work on

Sugars

• prepare water bath and add benedict's solution
• has sugar = colour is from blue to green, yellow or red

Starch

• iodine solution
• has starch = colour is from browny-orange to black 

Proteins

• biuret solution
• has protein = colour is from blue to purple

Lipids

• sudan III solution
• has lipids = mixture separates in two layers, top layer is red