Question

plspls help me in this answer it's urgent 19th and 20

Answer 1

19. arteries :

1. they have valves.

2. they are thick walled because the blood flows with immense pressure and thick wall prevents the bursting of the vesse

veins :

1. they do not have valves as their is no back flow of blood

2. they have thin walls as the blood does not flow with immense pressure

20.

1. the organ that produces insulin is pancreas.

2. the organ that produces bile is liver .