Biology B3



  • Movement of water, same process as diffusion
  • Across a partially permiable membrane
  • Movement is random
  • Requires no energy 
  • Water moves from a high concentration to an area of low concentration
  • From dilute solutions to more concentrated solutions
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Active Transport

  • Absorbtion of substances, not same process as diffusion
  • Across a partially permeable membrane
  • Requires energy from respiration
  • Absorbtion is done against a concentration gradient
  • Transport proteins attract molecule from out side cell
  • Transport protein rotates and releases it into cell
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Sports Drinks Dilemma

  • During exercise, glucose is used up
  • When you sweat your body cells loose water, you become dehydrated
  • Necessary to replace the water, glucose and mineral ions 
  • Sports drinks balance the concentration of body fluids 
  • If drink concentraion matches body fluids, solution is isotonic
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  • Large surface area, thin walls, short diffusion path
  • Surface area is increased by alveoli
  • Alveoli have thin walls, large surface area, good blood supply
  • Lungs are ventilated, maintains steep diffusion gradients
  • Oxygen diffuses into blood through alveoli
  • Carbon dioxide diffused out of blood, back into lungs, through alveoli
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Ventilating the Lungs

  • Lungs situated in thorax
  • Breath in: -intercostal muscels contract

                    -ribcage up and out, diaphragm flattens

                    -volume of thorax increases

                    -pressure of thorax decreases, draws air in

  • Breath out: -intercostal muscels relax

                      -ribcage down and in, diaphragm domed

                      -volume of thorax decreased

                      -pressure of thorax increased, air forced out

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Reasons Why People Cant Get Enough Oxygen

  • Alveoli are damaged, reducing surface area for gas exchange
  • Tubes leading to lungs are narrow
  • Person is paralysed, muscles will not move ridcage up and out
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Artificial Breathing Aids

  • 'Iron Lung'- vacuum effect creating negative pressure, when air was drawn out the persons chest moved out and they breathed in
  • 'Oxygen Mask'- positive pressure as measured amounts of air are forced into the lungs
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Exchange in the Gut

  • Food, digested into soluable molecules 
  • Small intestine absorbes solutes into blood
  • Villi line surface of small intestine and increase surface area, they are the exchanges surface for the absorption of food molecules
  • Villi, have thin walls and lots of capillaries 
  • Soluable products are absorbed in Villi by diffusion or active transport
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Exchange in Plants

  • Gas diffuse in and out of leaves through stomata
  • Size of stomata controlled by guard cells
  • Oxygen and Carbon dioxide diffused into and out of cell through stomata
  • Water vapour lost through stomata, due to evapouration in leaves
  • Water and mineral ions absorbed by roots, root hair cells increase surface area=quicker absorption
  • If more water is lost than absorbed, stomata close
  • Wilting reduces water loss, by reducing surface area
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  • Movement of water through plant=transpirtaion stream
  • Plants dehydrate if rate of evapouration in leaves is greater than water uptake
  • Evapouration more rapid in: hot, dry, windy, bright conditions
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Circulatory System (Heart)

  • Right pump: - takes blood from body

                       - forces deoxygenated blood into lungs

                       - where it picks up oxygen, looses carbon dioxide

                       - new oxygenated blood returns to the heart (left pump)

  • Left pump: - takes oxygenated blood from heart

                     - pumps it round the body

                     - left side of heart is more muscular, has to pump blood to whole of the body

  • Heart has 4 chambers: left and right atria (at the top) and the left and right ventricles (at the bottom)
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Circulatory System (Heart)

  • Right pump: - takes blood from body

                       - forces deoxygenated blood into lungs

                       - where it picks up oxygen, looses carbon dioxide

                       - new oxygenated blood returns to the heart (left pump)

  • Left pump: - takes oxygenated blood from heart

                     - pumps it round the body

                     - left side of heart is more muscular, has to pump blood to whole of the body

  • Heart has 4 chambers: left and right atria (at the top) and the left and right ventricles (at the bottom)
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Heart Chambers and Valves

  • The Atria: - recieves blood from the Vena Cava on the right

                    - recieves blood from the Pulmonary Vein on the left

  • The Atria contracts to force blood into the lower chambers, the Ventricles
  • The Ventricles: - forces blood into the Pulmonary Artery on the right

                            - forces blood into the Aorta on the left

  • The heart contains valves to stop blood from flowing the wrong way
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Keeping the Blood Flowing

  • Artery: - thick walls

                - small lumen

                - thick layer of muscle and elastic fibres

  • Vein: - large lumen

             - relatively thick walls

             - often have valves

  • Capillary: - thin vessels with narrow lumen

                   - walls are single cell thick

  • If blood vessels are blocked, organs will be deprives of oxygen and nutrients 
  • Stents are fitted to stop this
  • Leaky valves can be replaced by artificial ones or animal ones
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Transport in the Blood

  • Blood is a tissue made up of plasma
  • Plasma has white blood cells, red blood cells and platelets in it
  • Plasma transports: carbon dioxide, soluable productes of digestion, urea
  • White Blood Cell: - has a nucleus 

                               - part of defence system

  • Red Blood Cells: - biconcave

                              - no nucleus

                              - contains haemoglobin

                              - uses haemoglobin which combines with oxygen in lungs, to form oxyhaemoglodin, oxyhaemoglobin splits when it gets to organs for form oxygen and haemoglobin

  • Platelets: - no nucleus

                    - helps blood to clot at site of wound 

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Artificial or Real? - Blood

  • Blood Doners: Advantages - less expensive

                  - carries more oxygen

                  - dosen't cause side effects

Disadvantages - needs to be refrigerated

                      - has to be separated into cells and plasma

                      - blood has to be matched

  • Artificial Blood: Advantages - Perfluorocarbons (PFCs) doesn't need refrigerated 

                  - does not need matching to blood

Disadvantages - doesnt carry as much oxygen

                      - expensive

                      - can cause side effects

                      - inslouable in water, doesnt mix well with blood

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Artificial or Real? - Hearts

  • Heart Transplants:

Advantages - new heart, new life

Disadvantages - need to take immunosuppressents

                      - could be rejected

  • Artificial Hearts:

Advantages - dont need to match tissues

                  - no immunosupressents

Disadvantages - problems with blood clotting

                      - long stays in hospital

                      - expensive

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Transport Systems in Plants

  • 2 transport systems: - xylem transports water and mineral ions from root to stems to leaves

                                    - phloem transports food/sugars from leaves to other parts of the plant

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Controlling Internal Conditions

  • Homeostasis 
  • Waste products must be removed from the body eg: carbon dioxide and urea.
  • if there is too much water or ions, too much of them may move into or out of the cell, causing damage or destruction
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The Kidney

  • Filters the blood, getting rid of unwanted substances and keeping those the body needs
  • A heathly Kidney produces urine by: - filtering the blood

                                                          - reabsorbing all the sugars

                                                          - selectively reabsorbing the ions needed

                                                          - selectively reabsorbing as much water as needed

                                                          - releasing urea, excess water and ions in the blood

  • No protein should leave the blood when being filtered as it is too big
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  • Dialysis filters the blood outside of the body instead of the kidney
  • Blood leaves the body and enters a chamber with partially permiable membranes
  • Dialysis fluid flows outside the membranes
  • It contains the same useful substances as the blood needs, so none of the useful substances are diffused out of the blood
  • The fluid contains no urea, so all of the urea gets diffused out because of the steep concentration gradient
  • Disadvantage: - it has to be done every few days nd takes 3 hours
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Kidney Transplants

  • Donor must be a good match, so its not rejected
  • rejection means: the recipients antibodies attack the donor kidneys antigens, as they are seen as forgien
  • To stop rejection, have to take immunosuppressents
  • Disadvantage: - suppressing teh immune system can make the patients immune system vulnerable to common infections
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Controlling Body Temperature

  • Human body temperature must be kept at 37, otherwise enzymes stop working
  • Monitored and controlled by the thermoregulatory centre in the brain
  • It contains receptors which detect temperature of blood flwing through brain
  • Receptors ins kin also send impulses to brain about skin temperature
  • When temperature rises: - blood vessels near surface of skin dilate, more blood flow, more energy is transferred through radiation

                                         - sweating makes water evapourate off skin surface, takes heat energy from skin surface so it cools

  • When temperature falls: - blood vessels constrict, less heat energy is radiated 

                                        - shivering requires respirtaions and this small movement creates heat energy and warms the blood

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Controlling Blood Glucose

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Controlling Blood Glucose

  • The pancrease monitors the amount of glucose in the blood and releases insulin to contol it if it gets to high
  • The hormone Insulin controlls the amount of glucose in the blood by causing the excess glucose to move from the blood back into the cell
  • If there is too little insulin produced, the person has Type 1 Diabetes
  • If the blood glucose level gets too low, pancrease releases another hormone called glucagen
  • Glucagen causes glycogen to be converted back into glucose and released into th blood
  • Doctors are trying to find more ways to treat diabetes: - pancreas transplant

                                                                                    - transplanting pancreas cells

                                                                                    - using embryonic stem cells to produce insulin secreting cells

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Effects of Population Explosion

  • Humans are using more resources and producing more pollutants:
  • Land and water pollution: - sewage must be treated to remove gut parasites that may get into the land or water ways

                                          - landfills can leak toxic chemicals

                                          - herbicideds and pesticides can get into the soil or run off the land into water ways

  • Air pollution: - burning fossil fuels can produce sulfur dioxide which causes acid rain

                        - acid rain kills organisms eg: habitats, it chages the pH of the soil so damages roots, stops enzymes working as they are sensitive to changes of pH

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Deforestation and Peat Destruction

  • Deforestation leads to: - reduction of biodiversity (Biodiversity means having as wide a range of different species as possible)

                                      - increases the levels of carbon dioxide, as it is released in the burning if trees, and the destruction of peat bogs ect

                                      - raising cattle or growing rice in the new land areas releases methane

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Global Warming

  • An increase in the earths atmosphere can: - change the earths climate

                                                                   - rise sea levels

                                                                   - reduce biodiversity

                                                                   - cause changes in migration patterns

                                                                   - cause a change in the distribution of species

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  • Biofules are made from ethanol-bases
  • Produced by anaerobic fermentation and distilation
  • Microorganisms respire anaerobically to produce ethanol using sugars from crops
  • glucose is produced using a carbohydrase, ethanol is then extracted from the glucose by distillation 
  • carbon neutral, only the amount of carbon dioxide used for photosynthesis by the plants is released 
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  • Mainly methane
  • Produced during anearobic fermentation by bacteria
  • Made in a Large container, the dung from animals goes in, ferments, methane is made and released and any excess materials is turn into slurry and used as a fertiliser on crops
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Efficient Food Production

  • Short food chains make food production more efficient
  • It can be controlled by: - preventing the animals from moving, as this stops energy being wasted through movement

                                       - keeping the animals in warm sheds, to stop them from using energy for heat

  • Fish stocks can be maintained by controlling fishing quotas amd net size
  • Fungus Fusarium is grown to produce mycoprotein, grown aerobically on cheap sugar syrup made from waste starch, little energy is used 
  • Industrial fermenters have: - an air supply of oxygen for respiration

                                            - stirrers to keep microorganisms spread out

                                            - water-cooled jacket on outside, to stop the energy made by respirtation heating the contents

                                            - sensors to monitor pH and temperature

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ore majekodunmi


These notes were good however they were quite brief and required more detail

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