Biology Further

DIFFUSION = High > low conc.

OSMOSIS = High > low conc. through partially permeable membrane

ACTIVE TRANSPORT = Low > high conc. Needs ATP, used at cell membranes

Villi in the S.I. and Alveoli in the lungs have

• A large S/A

• + Blood supply

• Moistness

• Thin

...to aid diffusion

O2 = Air into bloodstream

CO2 = Bloodstream into air

ROOT HAIR CELLS - Large S/A to absorb H2O + Minerals

STOMATA - CO2 and water vapour in/out by diffusion. Known as TRANSPIRATION

Size of stomata controlled by GUARD CELLS

Plants lose H2O rapidly - stomata CLOSE

Transpiration is more rapid in hot and dry climates, therefore a thicker waxy cuticle

+ DIFFUSION - Leaves have flat shape and large internal air spaces

Transportation in body - CIRCULATORY system

• Heart
• Blood vessels

To cells or from body, pump blood

OXYGENATED blood flows FROM heart to organs through ARTERIES

DEOXYGENATED blood flows INTO heart through VEINS

Substances cells need pass out of blood

Substances cells produce pass into blood

PLASMA transports-

• CO2 - organs>lungs
• UREA - liver>kidney
• DIGESTED - S.I.>organs

Body needs +ENERGY during EXERCISE so muscles can contract

Changes to increase blood flow + supply of sugar and O2 and CO2 removal

• + Heart rate

• + Rate and depth of breath

• Arteries to muscles dilate

GLYCOGEN stores used

When muscles are tired, ANAEROBIC respiration used...

• Poisonous lactic acid created

• Glucose breakdown incomplete=less energy

Oxygen debt, repaid to oxidise lactic acid