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  • Created by: 09holconh
  • Created on: 03-05-14 17:08



Like DIFFUSION, it requires NO ENERGY and is RANDOM from cell to cell


The WATER moves from a HIGH to LOW concentration (a DILUTE to CONCENTRATED solution)

The cell membrane is PARTIALLY PERMIABLE

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Active Transport

Cells need to ABSORB substances which are in short supply (AGAINST the concentration gradient)

Cells use ACTIVE TRANSPHORT to ABSORB these substances across a SELECTIVELY PERMIABLE MEMBRANE (AGAINST the concentration gradient)


Cell are able to absorb IONS from DILUTE solutions. eg. Root hair cells absord from solutions in the soil by ACTIVE TRANSPORT

GLUCOSE can also be reabsorbed by the KIDNEY TUBULES by ACTIVE TRANSPORT

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The Sports Drink Dilema

When you exercise your cells need ENERGY from RESPIRATION

After a while you SWEAT to keep yourself cool, SWEAT contains MINERAL IONS and WATER, so you may become DEHYDRATED

If you exercise for a long time, you may need to replace the SUGAR, MINERAL IONS and WATER which have been lost

Sports drinks are solutions of SUGAR and MINERAL IONS. They help to REHYDRATE body cells

The drinks help balance the concentration of body fluids and the concentrations inside cells. If the drink combination matches the body fluids the solution is ISOTONIC

The benfits of sports drinks are varied. Some scientist think WATER is just as good for SHORT PERIODS of exercise. Whereas, ATHLETES may need to replace SUGAR and MINERAL IONS.

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Exchange in the Lungs

Large organisms have special EXCHANGE SURFACES to obtain the FOOD and OXYGEN they need.

Soluble food materials (SOLUTES) are absorbed by the INTESTINES, while OXYGEN is absorbed by the LUNGS and CARBON DIOXIDE removed from them.

Good Exchange Surfaces have:

  • Large SA to V ratio
  • Thin Walls (short diffusion path)
  • Good blood supply

The lungs have alveoli (air sacs) to increase their SA. Alveoli have THIN WALLS and A GOOD BLOOD SUPPLY.

The LUNGS are ventilated to achieve a STEEP CONCENTRATION GRADIENT

OXYGEN diffuses into the capillaries, surrounding the ALVEOLI and CARBON DIOXIDE diffuses back into the LUNGS to be breathed out

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Exchange in the Gut

The food we eat is DIGESTED into SMALL, SOLUBLE MOLECULES. In the SMALL INTESTINE these SOLUTES are absorbed into the BLOOD

The VILLI line the surface of the SMALL INTESTINE- they are the exchange surface for FOOD MOLECULES

The VILLI are finger-like projections which increase the SURFACE AREA for ABSORBTION

The wall of the VILLI are VERY THIN and there are MANY CAPILLARIES close to the WALL

The SOLUBLE products of digestion can be absorbed by the VILLI by DIFFUSION or ACTIVE TRANSPORT


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Exchange in Plants

GASES diffuse in and out through the STOMATA in the leaves of plants. The opening and closing of the STOMATA is controlled by the GUARD CELLS which surround them.

The GASES involved in DIFFUSION are:



Plants also lose WATER through the STOMATA due to EVAPORATION in the leaves

Leaves are thin, so GASES don't have to DIFFUSE very far. There are also internal AIR SPACES and a WAXY CUTICLE layer to stop WATER LOSS.

ROOT HAIR CELLS increase the SA of the ROOTS so more WATER and MINERAL IONS can be absorbed

If the plant is LOSING WATER quicker than it is GAINING it, the STOMATA will close to prevent the plant from WILTING

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Plants take up WATER through the ROOTS. The WATER passes through the plant to the LEAVES. In the LEAVES the WATER EVAPORTAES from the plant leaf cells and the WATER VAPOUR diffuses out of the STOMATA, during this more WATER is pulled up through the XYLEM to take its place

The name for this PROCESS is the TRANSPIRATION STREAM.

The plant would DEHYDRATE if the WATER LOSS happened more quickly then the uptake of WATER from the ROOTS

EVAPORATION happens more QUICKLY in:

  • Hot conditions
  • Dry conditions
  • Windy conditions
  • Bright conditions

The GUARD CELLS can close the STOMATA to prevent over EVAPORTATION and WILTING. WILTING also reduces the SA therefore, WATER LOSS.

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The Circulatory System

Large organisms need a TRANSPORT SYSTEM, to move MATERIAL around the body.

Humans have a CIRCULATORY SYSTEM which consists of BLOOD VESSELS, the HEART and BLOOD

The HEART is a MUSCULAR ORGAN that pumps blood around the body. It's two pumps held together.

The RIGHT pump (ON THE LEFT SIDE) forces DEOXYGENATED blood back to the lungs, where it loses CARBON DIOXIDE and gains OXYGEN

The LEFT pump (ON THE RIGHT SIDE) forces OXYGENATED blood to the cells so RESPIRATION can happen

The HEART has 4 chambers. The ATRIA at the top recieve deoxygenated blood from the VENA CAVA and oxygenated blood from the PULMONARY VEIN. The ARTIA move blood into the lower chambers the VENTRICLES. They force deoxygenated blood into the PULMONARY ARTERY and oxygenated blood into the AORTA. VALVES prevent blood from flowing the wrong way. The HEART recieves blood via the CORONARY ARTERIES and has DOUBLE CIRCULATION

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Keeping Blood Flowing

Blood flows in three main types of BLOOD VESSELS: the ARTERIES, VEINS and CAPILLARIES


  • Carry Blood AWAY from the HEART
  • Have THICK walls, containing MUSCLES and ELASTIC TISSUE


  • Have THINNER walls that ARTERIES
  • Have VALVES to prevent a BACKFLOW of BLOOD


  • Carry blood through ORGANS and allow exchange surfaces with all living cells in the body
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Keeping Blood Flowing

The blood flows through BLOOD VESSELS, so if they are BLOCKED the blood will not flow efficiently. Therefore, organs will be deprived of NUTRIENTS and OXYGEN

  • STENTS can be inserted to keep BLOOD VESSELS open. Particularly, when CORONARY ARTERIES become blocked due to FATTY DEPOSITES, cutting off the blood supply, to the HEART MUSCLE.
  • LEAKY VALVES mean blood could flow the wrong way. ARTIFICIAL or ANIMAL VALVES can be inserted to replace damaged VALVES.
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Transport in the Blood

Blood is a TISSUE. PLASMA contains RED BLOOD CELLS, WHITE BLOOD CELLS and PLATELETS. Blood PLASMA transports substances such as:

  • Carbon Dioxide- ORGANS to LUNGS
  • Soluble Digestion Products- SMALL INTESTINE to OTHER ORGANS
  • Urea- LIVER to KIDNEYS (URINE made)

Red Blood Cells:   Biconcave discs, no nucleus


White Blood Cells: Have a nucleus

  • Form part of the body's defence system against MICROORGANSIMS

Platelets: No nucleus

  • Small fragments of cells
  • Help form BLOOD CLOTS at the site of wounds
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Controlling internal conditions

Keeping conditions within a NARROW range is called HOMEOSTASIS. TEMPERATURE, BLOOD GLUCOSE, WATER, ION LEVELS and WASTE PRODUCTS must all be controlled.

WASTE PRODUCTS to be removed include:

  • Carbon Dioxide- RESPIRATION, removed via the LUNGS
  • Urea- breakdown of ALMINO ACIDS, LIVER to KIDNEYS removed via URINE

WATER and IONS enter the body when we eat and drink. If either is wrong OSMOSIS may occur poorly which could damage or destroy cells

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The Human Kidney

The body has 2 KIDNEYS. They filter BLOOD and excrete substances you DO NOT WANT, keeping those you NEED

A KIDNEY produces URINE by:

  • REABSORBING the amount of WATER the body needs

URINE is temporarily STORED in the BLADDER before being removed via the URETHRA

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Dialisis- Artificial Kidney

A person who suffers from KIDNEY FAILURE can be kept aliv by DIALYSIS

A DIALYSIS machine carries out th same job as the KIDNEYS. The blood flos between PARTIALLY PERMIABLE MEMBRANES

The DIALYSIS fluid contains the same CONCENTRATION of useful substances as the patients blood, e.g. GLUCOSE and MINERAL IONS. This means the substances don't have to DIFFUSE out of th blood, so they don't need to be REABSORBED. UREA diffuses from the blood to the DIALYSIS fluid.

DIALYSIS restores the CONCENTRATION of substances in the blood to normal, but needs to be carried out a REGULAR intervals.

If a KIDNEY becomes available the patient may have a KIDNEY TRANSPLANT. If the TRANSPLANT is successful, they will not need DIALYSIS.

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Kidney Transplants

A KIDNEY TRANSPLANT is a better option than DIALYSIS. The diseased KIDNEY is replaced with a HEALTHY one.

KIDNEYS can come from victims of fatal accidents or from living donors

The new KIDNEY must be a good TISSUE MATCH so the patients body doesn't REJECT it

There are PROTEINS, called ANTIGENS on the surface of cells. The recipients ANTIBODIES may attack the TISSUE if they recognise it as FOREIGN

After the transplant, the patient will have to take drugs to suppress the IMUNE SYSTEMS response. They are called IMMUNOSUPPRESSANT DRUGS

Despite advantages, there are some risks:

Treatments involve suppressing the patients IMMUNE SYSTEM - they are left vulnerable to common infections

The new KIDNEY is placed in the groin and attached to the BLOOD VESSELS and BLADER. The old KIDNEYS are left

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Controlling Body Temperature

The Human body temperature must be kept at about 37 degrees, for ENZYMES to work well. So, the CORE BODY TEMPERATURE must be kept stable

Body temp is controlled by the THERMOREGULATORY CENTRE in the BRAIN. The centre has RECEPTORS which detect the temp of the blood flowing through the BRAIN.

Temp receptors in the SKIN also send impulses to the brain to give information about SKIN temp. The skin looks RED we are hot due to INCREASED blood flow

Sweating helps COOL the body. When it's hot, more water is lost from the skin, so more water must be taken in via DRINKS and FOOD to balance the loss.
If the CORE TEMP rises:
-BLOOD VESSELS near the skin surface DILATE to allow more blood flow though skin CAPILLARIES. Energy transfer via RADIATION and skin cools

  • SWEAT GLANDS produce more SWEAT. It evaporates from the skins surface and this energy required comes to the skins surface and we cool down
    If the CORE TEMP falls:
    BLOOD VESSELS, near the skin surface, constrict and less blood flows through the skin CAPILLARIES. Less energy RADIATED
    We 'SHIVER' MUSCLES contract, requiring RESPIRATION energy release warms the blood
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Treatment and Temperature Issue

When doctors consider the best course of action for KIDNEY treatment patients they have to consider many issues:

  • The general HEALTH of the patient
  • How LONG the patient has been on DIALYSIS
  • The total COST of treatment and long term costs
  • The RISK of the operation e.g infection and anaesthetics
  • The AVAILABILITY of the donor KIDNEY

There are ETHICAL issues too:

  • Should EVERYONE be on the TRANSPLANT REGISTER Or should thy have to OPT IN
  • Should people be PAID to be DONORS
  • Should people PAY for a new KIDNEY to jump the queue

Carrying a donor card mean the family doesn't have to make the decision about organ donation, so soon after death

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Treatment and Temperature Issue

When doctors consider the best course of action for KIDNEY treatment patients they have to consider many issues:

  • The general HEALTH of the patient
  • How LONG the patient has been on DIALYSIS
  • The total COST of treatment and long term costs
  • The RISK of the operation e.g infection and anaesthetics
  • The AVAILABILITY of the donor KIDNEY

There are ETHICAL issues too:

  • Should EVERYONE be on the TRANSPLANT REGISTER Or should thy have to OPT IN
  • Should people be PAID to be DONORS
  • Should people PAY for a new KIDNEY to jump the queue

Carrying a donor card mean the family doesn't have to make the decision about organ donation, so soon after death

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Controlling Blood Glucose


If there is TOO MUCH GLUCOSE in our blood the PANCREAS produces the hormone INSULIN

INSULIN causes GLUCOSE to move from the blood into cells

In the LIVER excess GLUCOSE is stored as GLYCOGEN

If no or little INSULIN is produced in the PANCREAS the blood GLUCOSE levels could become very high. This is known as TYPE 1 DIABETES

TYPE 1 DIABETES is controlled with INSULIN injections and careful attention to diet and exercise.

If the levels get too low PANCREAS receptors detect this
The GLUCAGON causes GLYCOGEN in the LIVER to turn back into GLUCOSE
GLUCOSE is released back into the blood

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Treating Diabetes

TYPE 1 DIABETES is treated with INSULIN injections, which are produced by GENETICALLY ENGINEERED BACTERIA

The DIABETIC has to inject before every meal

Very active DIABETICS have to match the amount on INSULIN injected with their DIET and EXERCISE

Some DIABETICS use pumps attached to the body, they can adjust the level of INSULIN being injected

Doctors and scientists are investigating other treatments and cures for TYPE 1 DIABETES


PANCREAS transplants
Transplanting PANCREAS cells
Using EMBRYONIC STEM CELLS to produce insulin secreting cells
Using ADULT STEM CELLS from DIABETIC patient la
GENETICALLY ENGINEERING PANCREAS cells to make them work properly

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The Effects of Population Explosion

There are increasing numbers of people on our planet. Currently the population is about 7 million

Many people want a better standard of living

We are using in RAW MATERIALS and those that are NON-RENEWABLE cannot be replaced

When goods are produced there is a lot of INDUSTRIAL WASTE. We are producing more waste and therefore pollution

Humans reduce the amount of land available for animals and plants by building quarrying, farming and dumping waste

The permanent increase in populations affect the ECOLOGY of the EARTH

Humans pollute:
WATERWAYS with SEWAGE, FERTILISER and toxic chemicals
AIR with smoke and gases like SULPHUR DIOXIDE which contributes to ACUD RAIN
LAND with toxic chemical a such as PESTICIDES and HERBICIDES and these can be washed into the water

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Land and Water Pollution

People pollute LAND in many different ways:    SEWAGE contains HUMAN BODY WASTE from our homes. SEWAGE must be treated properly to remove gut PARASITES and TOXIC CHEMICALS or these can get into the land.

Large quantities of household and indistrial WASTE are placed in landfill and TOXIC CHEMICALS leak out. Some industrial waste such as, RADIOACTIVE WASTE, is very HAZARDOUS.

FARMING METHODS can pollute the land

HERBICIDES and PESTICIDES (killing insects) are also poisons. They are sprayed onto crops and get into the soil and the food chain. Eventually, many are washed into rivers.

Water Pollution:    HERBICIDES, PESTICIDES and CHEMICAL FERTILISERS all get washed into rivers and streams

FERTILISERS and UNTREATED SEWAGE can casue a high NITRATE level in the water

TOXIC CHEMICALS from landfill also leak into the waterways and pollute the water, killing fish

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Air Pollution

Burning FOSSIL FUELS produces SULPHUR DIOXIDE and other acidic gases. Power stations and cars release acidic gases.

The SULPHUR DIOXIDE dissolves in water in the air, forming ACIDIC SOLUTIONS

The SOLUTIONS then fall as ACID RAIN- sometimes far from where the gases were produced

ACID RAIN kills organisms and trees can be damaged if the leaves are soaked in ACID RAIN for long periods of time

ACID RAIN can change the soil PH, this damages roots and may release toxic minerals. For example, aluminium ions are released which damage organisms in the soil and in waterways

ENZYMES are sensitive to PH

When trees are damaged food and habitats for many other organisms are lost.

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Deforestation and Peat Distruction

DEFORESTATION is trees being cut down. Large scale DEFORESTATION in tropical areas is due to the need for TIMBER and to provide LAND for agriculture


Increased the release of CARBON DIOXIDE into the atmosphere due to the burning of tree and the decay of wood, by MICROORGANISMS

Reduced the rate at which CARBON DIOXIDE is being removed from the atmosphere, via PHOTOSYNTHESIS


DEFORESTATION has occured so that:

Crops can grow to produce ethanol- based BIOFUELS, There can be an increase of cattle or rice fields- METHANE

The destruction of PEAT BOGS also release CARBON DIOXIDE, PEAT is used for compost- decayed by MICROORGANISMS.

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Global Warming

In normal nature CARBON DIOXIDE is released into the air via RESPIRATION and it is removed by PLANTS and ALGAE in PHOTOSYNTHESIS

CARBON DIOXIDE is also absorbed by water bodies (sequestered- stored)

Levels of CARBON DIOXIDE and METHANE are increasing in the atmosphere. They are GREENHOUSE GASES and cause the GREENHOUSE EFFECT. Most scientists believe an increase in GREENHOUSE GASES contributes to GLOBAL WARMING

The earths increasing TEMPERATURE may:

-Cause big changes to the earths climate

-Cause a rise in sea level- melting of ice caps and glaciers

-Reduce biodiversity

-Cause changes in migration patterns

-Result in changes of distribution

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Biofuels are made from NATURAL products. Two types of BIOFUEL are BIOGAS and ETHANOL-BASED FUELS.


MICROOGANISMS RESPIRE anaerobically to produce ETHANOL, using sugars from crops

GLUCOSE is produced from MAIZE STARCH by the action of CARBOHYDRASE

The GLUCOSE and SUGAR cane juices can be FERMENTED by YEAST to produce ETHANOL

The ETHANOL is extracted by DISTILLATION and can be used as fuel in motor vehicles

Using ETHANOL as a fuel could replace FOSSIL FUELS and would be more 'CARBON FRIENDLY'

ETHANOL is CARBON NEUTRAL the CARBON DIOXIDE used for PHOTOSYNTHESIS by the crops is returned to the atmosphere when ETHANOL is BURNED.

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Biogas, mainly METHANE can be produced using ANAEROBIC FERMENTATION by BACTERIA

PLANTS and any waste material containing CARBOHYDRATE e.g. CATTLE DUNG can be broken down by BIOGAS GENERATORS

The GENERATORS provide IDEAL conditions for BACTERIA to reproduce and ferment the carbs. A suitable TEMP must be remained and some GENERATORS mix the contents. They are either in the ground or have INSULATING JACKETS for INSULATION

Large scale GENERATORS use wast from SUGAR FACTORIES or SEWAGE works

Small scale can be used by a HOME or a FARM

The gas produced can provide energy for HEATING etc. The more METHANE in the gas mixture, the better quality of the gas.

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Making Food Production Efficient

The shorter the FOOD CHAIN the LESS ENERGY WASTED. Therefore, its more efficient for us to eat plants than to eat animals

We can produce MEAT efficiently by:

-Preventing the animal from moving, so it doesn't WASTE energy on contracting muscles- RESPIRATION

-Keeping the animal WARM in sheds so it doesn't use as much ENERGY maintaining body temperature.

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Sustainable Food Production


FISH STOCKS in OCEANS are monitored


can only remove a strict allocation of fish per year- a quota

must use certain sized nets to avoid catching small, young fish

FUSARIUM, a fungus, is used to produce MYCOPROTEIN. A PROTEIN rich food suitable for vegetarians. FUSARIUM is grown AEROBICALLY on cheep sugar syrup made from waste starch, then the MYCOPROTEIN in harvested.

  • MICROORGANISMS can be grown on a large scale in industrial FERMENTERS
  • They have large vessels whic have:
  • An air supply for RESPIRATION
  • Stirrers to make sure OXYGEN get to all of it- RESPIRATION and maintain temp
  • A water cooled jacket, to maintain heat
  • Sensors to monitor TEMP and PH BALANCE
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Environmental Issues

Human activities which effect the global environment:

  • Builing DAMS, to store water in RESEVOIRS- loss of HABITAT and LAND to grow CROPS

Data produced all arouund the world is difficult to say if it is RELIABLE and VALID

Scientist come to DIFFERENT CONCLUSIONS with the same data- opinion based

GLOBAL WARMING divides opinion. Some argue the EARTHS TEMP has increased due to a NATURAL CYCLE 

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