Biology Textbook P.146

Q.5

i ) ( 1 ) artery   ( 2 ) blood capillary

ii ) A – thicker wall to withstand high blood pressure

    B – one cell thick to facilitate exchange of substances

iii ) increase surface area for diffusion of gases

iv ) – decrease blood supply to heart muscle

  -  decrease oxygen and food supply to heart muscle

  -  heart muscle cells die / heart attack occur

Q.6

i ) left ventricle

ii ) pressure increase sharply, because muscle of Q contract

iii ) ( 1 ) closed

      ( 2 ) pressure in Q is greater than that in P, thus closing valve A,

             the heart tendon prevent valve A from turning into the left

             atrium

iv ) the unidirectional flow of blood through the heart cannot be

     maintained, less blood is pumped out of the heart

v ) ( 1 ) P   ( 2 ) S

Q.8

i ) large total cross sectional area,

    reduce rate of blood flow and allow more time for exchange of substances

ii ) pressure of A near the arterial end is higher than that of fluid B

     some plasma except large protein

   are forced through the wall of P

iii ) ( 1 ) right atrium

      ( 2 ) contraction of skeletal muscles help to push fluid C along the

             lymph vessel, valves of lymph vessels prevent backflow of lymph