Further Biology 1

7/30/2019 Further Biology 1

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Further Biology: B3

Exchanges

Type of exchange Type of Molecules Concentration Gradient Energy

Diffusion Small, dissolved (O2, CO2) Down (high to low) KineticOsmosis Mainly water, solvent Down (high to low) Kinetic

Active Transport small (e.g. glucose), ions Up (low to high) ATP (from respiration)

Diffusion

DIFFUSION IS THE RANDOM MOVEMENT OF SOLUTE PARTICLES/DISSOLVED SUBSTANCES FROM AN AREA OF HIGH

CONCENTRATION TO AN AREA OF LOW CONCENTRATION.

To speed up diffusion:

Decrease the distance Increase the concentration gradient Increase the surface area Good ventilation (in gaseous exchanges) Good blood supply

Osmosis

OSMOSIS IS THE RANDOM MOVEMENT OF SOLVENT MOLECULES (USUALLY WATER) ACROSS A PARTIALLY PERMEABLE

MEMBRANE FROM A REGION OF HIGH CONCENTRATION TO A REGION OF LOW CONCENTRATION

Partially permeable membrane is a thin membrane containing tiny pores that allows smallmolecules to pass (e.g. water) but not bigger ones (e.g. ions and sugar molecules).

Molecules move about randomly but the net (overall) movement of particles is along theconcentration gradient.

Depending on the concentration of the solution that surrounds a cell (tissue fluid, which is providedby the blood capillaries), water will move into or out of the cell through osmosis.

Higher

concentration

of solutes on

the outside ofthe cell

Lower

concentration of

solutes on the

outside of the cell

Concentrations of

solutes are the same in

the external solution

and cell contentRed blood cells

Plant cells


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Acti ve Tr an sport

THE TRANSPORTATION OF MOLECULES FROM A LOW CONCENTRATION TO A HIGH CONCENTRATION (AGAINST THE

CONCENTRATION GRADIENT) USING ATP (ENERGY FROM RESPIRATION)

Energy is required as carrier proteinspick up specific molecules and take

them through the cellmembrane.

Therefore, cells usingactive transport have lots

of mitochondria as thats where

respiration happens.

If respiration stops, activetransport stops.

EXAMPLES

Location Exchange Substance From To Adaption

Lung Diffusion oxygen air space red blood

cells

alveoli (thin walls short distance for diffusion,

moist lining, large surface area, good blood supply)

Diffusion carbon

dioxide

blood

plasma

air space same as above

Small

intestine

Diffusion digested

food

stomach,

intestine

blood villi (extends to microvilli for large surface, thin

single layer of surface cells, good blood supply

many capillaries)

Leaf Diffusion oxygen and

water

vapour

leaf cell air space stomata (flat shape of the leaf, air spaces and

spongy layer increase surface area, thin leaves

short distance)

Root Osmosis Water and

mineral ion

soil Root cells Root hair cell (tube like extension short distance,

lots of root hairs increase surface area)

Root Active

Transport

Nitrate ions Soil Root cells Root hair cell (lots of mitochondria)

Diffusion in Lungs Diffusion in the

small intestine


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Its important for the body parts to be highly

specialised as the size and complexity of an

organism increases the difficulty of exchanging

materials.

Sports Drinks

If the water and ions lost are not replaced,the ion/water balance of the body is

disturbed.

Sweating releases more water than ions sothe balance is disrupted as there is a higher

ion concentration in the blood.

This causes cells in the body to not work asefficiently.

All drinks help to rehydrate the body(replace lost water)

Soft drinks contain water, sugar, ions and flavourings but concentrations can vary greatly. Sport drinks contain sugar to replace the glucose lost during exercise and water and ions.

Diffusion in a leaf

Active Transport in

the roots

Osmosis in the roots

The loss of the water from the

surface of a plants leaves is

called transpiration. The rate of

transpiration increases in hot,

dry and windy conditions. If

plants lose water faster than it is

replaced by the roots the guard

cells deflate and the stomata

close, to prevent wilting.


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Gaseous exchange in Humans: Ventilation

Intercostal muscles

contract expanding theribcage up and outwards

Volume of the thorax (upper body)

increases. Increasing the volume of

a gas decreases the gas pressure.

Therefore, the pressure inside the

lungs is lower, compared to

outside. This causes air to move

into the lungs.

Diaphragm muscles

contract, pulling down the

central part diaphragm and

flattening it

Diaphragm muscles relax,

curving the diaphragm

back up.

Diaphragm: a sheet of

muscle and fibre

Lungs expand during this process

INSPIRATION

EXPIRATION

Intercostal muscles relax

making the ribcage smaller

as ribs move down and in

Lungs return to their original

size during this process due to

their elastic recoil

Volume of the thorax

decreases. Decreasing the

volume of a gas increases the

gas pressure. Therefore,

pressure of air inside the lungs

is greater than the air outside

so air moves out of the lungs.


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Ventilators

Devices that help patients breathe who cannot automatically do so due to disease or injury.

Negative-Pressure Ventilators

E.g. the iron lung, developed for use during epidemics of poliomyelitis as breathing muscles stopped

functioning, was a large tank enclosing the whole patients body except the head and neck. A pump removes

the air from the tank, creating a vacuum. This causes the patients thorax to expand and therefore, inhale.

The vacuum is them released, the thorax and lungs recoil, and the patient exhales.

Positive-Pressure Ventilators

A metal tube is inserted through the mouth and into the windpipe, forcing air into a patients lungs. Its

commonly used in operations and intensive care units. For long term use, the tube is inserted surgically

through the neck into the trachea.

Hand-controlled Ventilators

Bag-mouth-mask ventilators are often used by paramedics as resuscitators. Air is supplied via a bag which is

squeezed manually or operated by a pump.

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Further Biology 1